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[PATCHv9 00/32] THP-enabled tmpfs/shmem using compound pages

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  [PATCHv9 00/32] THP-enabled tmpfs/shmem using compound pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-06 16:20 +0200
    [PATCHv9 11/32] thp: skip file huge pmd on copy_huge_pmd() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-06 16:20 +0200
    [PATCHv9 09/32] thp: handle file pages in split_huge_pmd() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-06 16:30 +0200
    [PATCHv9 06/32] mm: introduce do_set_pmd() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-06 16:30 +0200
    [PATCHv9 13/32] thp: run vma_adjust_trans_huge() outside i_mmap_rwsem "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-06 16:30 +0200
    [PATCHv9 04/32] mm: postpone page table allocation until we have page to map "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-06 16:30 +0200
    [PATCHv9-rebased 24/32] shmem: add huge pages support "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 25/32] shmem, thp: respect MADV_{NO,}HUGEPAGE for file mappings "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 06/32] mm: introduce do_set_pmd() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 16/32] vmscan: split file huge pages before paging them out "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 07/32] thp, vmstats: add counters for huge file pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 23/32] shmem: get_unmapped_area align huge page "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 19/32] filemap: prepare find and delete operations for huge pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 30/32] thp: introduce CONFIG_TRANSPARENT_HUGE_PAGECACHE "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 01/32] thp, mlock: update unevictable-lru.txt "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 13/32] thp: run vma_adjust_trans_huge() outside i_mmap_rwsem "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 04/32] mm: postpone page table allocation until we have page to map "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 28/32] shmem: make shmem_inode_info::lock irq-safe "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 32/32] thp: update Documentation/{vm/transhuge,filesystems/proc}.txt "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 27/32] khugepaged: move up_read(mmap_sem) out of khugepaged_alloc_page() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 10/32] thp: handle file COW faults "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 29/32] khugepaged: add support of collapse for tmpfs/shmem pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 31/32] shmem: split huge pages beyond i_size under memory pressure "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:10 +0200
    [PATCHv9-rebased 02/32] mm: do not pass mm_struct into handle_mm_fault "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:20 +0200
    [PATCHv9-rebased 21/32] mm, rmap: account shmem thp pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:20 +0200
    [PATCHv9-rebased 12/32] thp: prepare change_huge_pmd() for file thp "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:20 +0200
    [PATCHv9-rebased 08/32] thp: support file pages in zap_huge_pmd() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:20 +0200
    [PATCHv9-rebased 05/32] rmap: support file thp "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:20 +0200
    [PATCHv9-rebased 11/32] thp: skip file huge pmd on copy_huge_pmd() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:20 +0200
    [PATCHv9-rebased 00/32] THP-enabled tmpfs/shmem using compound pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:20 +0200
      [PATCHv9-rebased 22/32] shmem: prepare huge= mount option and sysfs knob "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:20 +0200
      [PATCHv9-rebased 15/32] thp, mlock: do not mlock PTE-mapped file huge pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:20 +0200
      [PATCHv9-rebased 17/32] page-flags: relax policy for PG_mappedtodisk and PG_reclaim "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:20 +0200
      [PATCHv9-rebased 20/32] truncate: handle file thp "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:20 +0200
      [PATCHv9-rebased 18/32] radix-tree: implement radix_tree_maybe_preload_order() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:20 +0200
      [PATCHv9-rebased 09/32] thp: handle file pages in split_huge_pmd() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:20 +0200
      [PATCHv9-rebased 14/32] thp: file pages support for split_huge_page() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-07 13:20 +0200

Page 2 of 2 — ← Prev page 1 [2]

#1416021 — [PATCHv9-rebased 10/32] thp: handle file COW faults

File COW for THP is handled on pte level: just split the pmd.

It's not clear how benefitial would be allocation of huge pages on COW
faults. And it would require some code to make them work.

I think at some point we can consider teaching khugepaged to collapse
pages in COW mappings, but allocating huge on fault is probably
overkill.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 mm/memory.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/memory.c b/mm/memory.c
index 7f2e16e9f0cb..a9501e2851d8 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3466,6 +3466,11 @@ static int wp_huge_pmd(struct fault_env *fe, pmd_t orig_pmd)
 	if (fe->vma->vm_ops->pmd_fault)
 		return fe->vma->vm_ops->pmd_fault(fe->vma, fe->address, fe->pmd,
 				fe->flags);
+
+	/* COW handled on pte level: split pmd */
+	VM_BUG_ON_VMA(fe->vma->vm_flags & VM_SHARED, fe->vma);
+	split_huge_pmd(fe->vma, fe->pmd, fe->address);
+
 	return VM_FAULT_FALLBACK;
 }
 
-- 
2.8.1

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#1416022 — [PATCHv9-rebased 29/32] khugepaged: add support of collapse for tmpfs/shmem pages

This patch extends khugepaged to support collapse of tmpfs/shmem pages.
We share fair amount of infrastructure with anon-THP collapse.

Few design points:

  - First we are looking for VMA which can be suitable for mapping huge
    page;

  - If the VMA maps shmem file, the rest scan/collapse operations
    operates on page cache, not on page tables as in anon VMA case.

  - khugepaged_scan_shmem() finds a range which is suitable for huge
    page. The scan is lockless and shouldn't disturb system too much.

  - once the candidate for collapse is found, collapse_shmem() attempts
    to create a huge page:

      + scan over radix tree, making the range point to new huge page;

      + new huge page is not-uptodate, locked and freezed (refcount
        is 0), so nobody can touch them until we say so.

      + we swap in pages during the scan. khugepaged_scan_shmem()
        filters out ranges with more than khugepaged_max_ptes_swap
	swapped out pages. It's HPAGE_PMD_NR/8 by default.

      + old pages are isolated, unmapped and put to local list in case
        to be restored back if collapse failed.

  - if collapse succeed, we retract pte page tables from VMAs where huge
    pages mapping is possible. The huge page will be mapped as PMD on
    next minor fault into the range.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 include/linux/shmem_fs.h           |  23 ++
 include/trace/events/huge_memory.h |   3 +-
 mm/khugepaged.c                    | 435 ++++++++++++++++++++++++++++++++++++-
 mm/shmem.c                         |  56 ++++-
 4 files changed, 500 insertions(+), 17 deletions(-)

diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index 94eaaa2c6ad9..0890f700a546 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -54,6 +54,7 @@ extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr,
 		unsigned long len, unsigned long pgoff, unsigned long flags);
 extern int shmem_lock(struct file *file, int lock, struct user_struct *user);
 extern bool shmem_mapping(struct address_space *mapping);
+extern bool shmem_huge_enabled(struct vm_area_struct *vma);
 extern void shmem_unlock_mapping(struct address_space *mapping);
 extern struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
 					pgoff_t index, gfp_t gfp_mask);
@@ -64,6 +65,19 @@ extern unsigned long shmem_swap_usage(struct vm_area_struct *vma);
 extern unsigned long shmem_partial_swap_usage(struct address_space *mapping,
 						pgoff_t start, pgoff_t end);
 
+/* Flag allocation requirements to shmem_getpage */
+enum sgp_type {
+	SGP_READ,	/* don't exceed i_size, don't allocate page */
+	SGP_CACHE,	/* don't exceed i_size, may allocate page */
+	SGP_NOHUGE,	/* like SGP_CACHE, but no huge pages */
+	SGP_HUGE,	/* like SGP_CACHE, huge pages preferred */
+	SGP_WRITE,	/* may exceed i_size, may allocate !Uptodate page */
+	SGP_FALLOC,	/* like SGP_WRITE, but make existing page Uptodate */
+};
+
+extern int shmem_getpage(struct inode *inode, pgoff_t index,
+		struct page **pagep, enum sgp_type sgp);
+
 static inline struct page *shmem_read_mapping_page(
 				struct address_space *mapping, pgoff_t index)
 {
@@ -71,6 +85,15 @@ static inline struct page *shmem_read_mapping_page(
 					mapping_gfp_mask(mapping));
 }
 
+static inline bool shmem_file(struct file *file)
+{
+	if (!IS_ENABLED(CONFIG_SHMEM))
+		return false;
+	if (!file || !file->f_mapping)
+		return false;
+	return shmem_mapping(file->f_mapping);
+}
+
 extern bool shmem_charge(struct inode *inode, long pages);
 extern void shmem_uncharge(struct inode *inode, long pages);
 
diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h
index bda21183eb05..830d47d5ca41 100644
--- a/include/trace/events/huge_memory.h
+++ b/include/trace/events/huge_memory.h
@@ -29,7 +29,8 @@
 	EM( SCAN_DEL_PAGE_LRU,		"could_not_delete_page_from_lru")\
 	EM( SCAN_ALLOC_HUGE_PAGE_FAIL,	"alloc_huge_page_failed")	\
 	EM( SCAN_CGROUP_CHARGE_FAIL,	"ccgroup_charge_failed")	\
-	EMe( SCAN_EXCEED_SWAP_PTE,	"exceed_swap_pte")
+	EM( SCAN_EXCEED_SWAP_PTE,	"exceed_swap_pte")		\
+	EMe(SCAN_TRUNCATED,		"truncated")			\
 
 #undef EM
 #undef EMe
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 84c2bf01ae42..8f333663510a 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -14,6 +14,7 @@
 #include <linux/userfaultfd_k.h>
 #include <linux/page_idle.h>
 #include <linux/swapops.h>
+#include <linux/shmem_fs.h>
 
 #include <asm/tlb.h>
 #include <asm/pgalloc.h>
@@ -42,7 +43,8 @@ enum scan_result {
 	SCAN_DEL_PAGE_LRU,
 	SCAN_ALLOC_HUGE_PAGE_FAIL,
 	SCAN_CGROUP_CHARGE_FAIL,
-	SCAN_EXCEED_SWAP_PTE
+	SCAN_EXCEED_SWAP_PTE,
+	SCAN_TRUNCATED,
 };
 
 #define CREATE_TRACE_POINTS
@@ -296,7 +298,7 @@ struct attribute_group khugepaged_attr_group = {
 	.name = "khugepaged",
 };
 
-#define VM_NO_KHUGEPAGED (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
+#define VM_NO_KHUGEPAGED (VM_SPECIAL | VM_HUGETLB)
 
 int hugepage_madvise(struct vm_area_struct *vma,
 		     unsigned long *vm_flags, int advice)
@@ -823,6 +825,10 @@ static bool hugepage_vma_check(struct vm_area_struct *vma)
 	if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
 	    (vma->vm_flags & VM_NOHUGEPAGE))
 		return false;
+	if (shmem_file(vma->vm_file)) {
+		return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff,
+				HPAGE_PMD_NR);
+	}
 	if (!vma->anon_vma || vma->vm_ops)
 		return false;
 	if (is_vma_temporary_stack(vma))
@@ -1203,6 +1209,412 @@ out:
 	return ret;
 }
 
+#ifdef CONFIG_SHMEM
+static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
+{
+	struct vm_area_struct *vma;
+	unsigned long addr;
+	pmd_t *pmd, _pmd;
+
+	i_mmap_lock_write(mapping);
+	vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
+		/* probably overkill */
+		if (vma->anon_vma)
+			continue;
+		addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
+		if (addr & ~HPAGE_PMD_MASK)
+			continue;
+		if (vma->vm_end < addr + HPAGE_PMD_SIZE)
+			continue;
+		pmd = mm_find_pmd(vma->vm_mm, addr);
+		if (!pmd)
+			continue;
+		/*
+		 * We need exclusive mmap_sem to retract page table.
+		 * If trylock fails we would end up with pte-mapped THP after
+		 * re-fault. Not ideal, but it's more important to not disturb
+		 * the system too much.
+		 */
+		if (down_write_trylock(&vma->vm_mm->mmap_sem)) {
+			spinlock_t *ptl = pmd_lock(vma->vm_mm, pmd);
+			/* assume page table is clear */
+			_pmd = pmdp_collapse_flush(vma, addr, pmd);
+			spin_unlock(ptl);
+			up_write(&vma->vm_mm->mmap_sem);
+			atomic_long_dec(&vma->vm_mm->nr_ptes);
+			pte_free(vma->vm_mm, pmd_pgtable(_pmd));
+		}
+	}
+	i_mmap_unlock_write(mapping);
+}
+
+/**
+ * collapse_shmem - collapse small tmpfs/shmem pages into huge one.
+ *
+ * Basic scheme is simple, details are more complex:
+ *  - allocate and freeze a new huge page;
+ *  - scan over radix tree replacing old pages the new one
+ *    + swap in pages if necessary;
+ *    + fill in gaps;
+ *    + keep old pages around in case if rollback is required;
+ *  - if replacing succeed:
+ *    + copy data over;
+ *    + free old pages;
+ *    + unfreeze huge page;
+ *  - if replacing failed;
+ *    + put all pages back and unfreeze them;
+ *    + restore gaps in the radix-tree;
+ *    + free huge page;
+ */
+static void collapse_shmem(struct mm_struct *mm,
+		struct address_space *mapping, pgoff_t start,
+		struct page **hpage, int node)
+{
+	gfp_t gfp;
+	struct page *page, *new_page, *tmp;
+	struct mem_cgroup *memcg;
+	pgoff_t index, end = start + HPAGE_PMD_NR;
+	LIST_HEAD(pagelist);
+	struct radix_tree_iter iter;
+	void **slot;
+	int nr_none = 0, result = SCAN_SUCCEED;
+
+	VM_BUG_ON(start & (HPAGE_PMD_NR - 1));
+
+	/* Only allocate from the target node */
+	gfp = alloc_hugepage_khugepaged_gfpmask() |
+		__GFP_OTHER_NODE | __GFP_THISNODE;
+
+	new_page = khugepaged_alloc_page(hpage, gfp, node);
+	if (!new_page) {
+		result = SCAN_ALLOC_HUGE_PAGE_FAIL;
+		goto out;
+	}
+
+	if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) {
+		result = SCAN_CGROUP_CHARGE_FAIL;
+		goto out;
+	}
+
+	new_page->index = start;
+	new_page->mapping = mapping;
+	__SetPageSwapBacked(new_page);
+	__SetPageLocked(new_page);
+	BUG_ON(!page_ref_freeze(new_page, 1));
+
+
+	/*
+	 * At this point the new_page is 'frozen' (page_count() is zero), locked
+	 * and not up-to-date. It's safe to insert it into radix tree, because
+	 * nobody would be able to map it or use it in other way until we
+	 * unfreeze it.
+	 */
+
+	index = start;
+	spin_lock_irq(&mapping->tree_lock);
+	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
+		int n = min(iter.index, end) - index;
+
+		/*
+		 * Handle holes in the radix tree: charge it from shmem and
+		 * insert relevant subpage of new_page into the radix-tree.
+		 */
+		if (n && !shmem_charge(mapping->host, n)) {
+			result = SCAN_FAIL;
+			break;
+		}
+		nr_none += n;
+		for (; index < min(iter.index, end); index++) {
+			radix_tree_insert(&mapping->page_tree, index,
+					new_page + (index % HPAGE_PMD_NR));
+		}
+
+		/* We are done. */
+		if (index >= end)
+			break;
+
+		page = radix_tree_deref_slot_protected(slot,
+				&mapping->tree_lock);
+		if (radix_tree_exceptional_entry(page) || !PageUptodate(page)) {
+			spin_unlock_irq(&mapping->tree_lock);
+			/* swap in or instantiate fallocated page */
+			if (shmem_getpage(mapping->host, index, &page,
+						SGP_NOHUGE)) {
+				result = SCAN_FAIL;
+				goto tree_unlocked;
+			}
+			spin_lock_irq(&mapping->tree_lock);
+		} else if (trylock_page(page)) {
+			get_page(page);
+		} else {
+			result = SCAN_PAGE_LOCK;
+			break;
+		}
+
+		/*
+		 * The page must be locked, so we can drop the tree_lock
+		 * without racing with truncate.
+		 */
+		VM_BUG_ON_PAGE(!PageLocked(page), page);
+		VM_BUG_ON_PAGE(!PageUptodate(page), page);
+		VM_BUG_ON_PAGE(PageTransCompound(page), page);
+
+		if (page_mapping(page) != mapping) {
+			result = SCAN_TRUNCATED;
+			goto out_unlock;
+		}
+		spin_unlock_irq(&mapping->tree_lock);
+
+		if (isolate_lru_page(page)) {
+			result = SCAN_DEL_PAGE_LRU;
+			goto out_isolate_failed;
+		}
+
+		if (page_mapped(page))
+			unmap_mapping_range(mapping, index << PAGE_SHIFT,
+					PAGE_SIZE, 0);
+
+		spin_lock_irq(&mapping->tree_lock);
+
+		VM_BUG_ON_PAGE(page_mapped(page), page);
+
+		/*
+		 * The page is expected to have page_count() == 3:
+		 *  - we hold a pin on it;
+		 *  - one reference from radix tree;
+		 *  - one from isolate_lru_page;
+		 */
+		if (!page_ref_freeze(page, 3)) {
+			result = SCAN_PAGE_COUNT;
+			goto out_lru;
+		}
+
+		/*
+		 * Add the page to the list to be able to undo the collapse if
+		 * something go wrong.
+		 */
+		list_add_tail(&page->lru, &pagelist);
+
+		/* Finally, replace with the new page. */
+		radix_tree_replace_slot(slot,
+				new_page + (index % HPAGE_PMD_NR));
+
+		index++;
+		continue;
+out_lru:
+		spin_unlock_irq(&mapping->tree_lock);
+		putback_lru_page(page);
+out_isolate_failed:
+		unlock_page(page);
+		put_page(page);
+		goto tree_unlocked;
+out_unlock:
+		unlock_page(page);
+		put_page(page);
+		break;
+	}
+
+	/*
+	 * Handle hole in radix tree at the end of the range.
+	 * This code only triggers if there's nothing in radix tree
+	 * beyond 'end'.
+	 */
+	if (result == SCAN_SUCCEED && index < end) {
+		int n = end - index;
+
+		if (!shmem_charge(mapping->host, n)) {
+			result = SCAN_FAIL;
+			goto tree_locked;
+		}
+
+		for (; index < end; index++) {
+			radix_tree_insert(&mapping->page_tree, index,
+					new_page + (index % HPAGE_PMD_NR));
+		}
+		nr_none += n;
+	}
+
+tree_locked:
+	spin_unlock_irq(&mapping->tree_lock);
+tree_unlocked:
+
+	if (result == SCAN_SUCCEED) {
+		unsigned long flags;
+		struct zone *zone = page_zone(new_page);
+
+		/*
+		 * Replacing old pages with new one has succeed, now we need to
+		 * copy the content and free old pages.
+		 */
+		list_for_each_entry_safe(page, tmp, &pagelist, lru) {
+			copy_highpage(new_page + (page->index % HPAGE_PMD_NR),
+					page);
+			list_del(&page->lru);
+			unlock_page(page);
+			page_ref_unfreeze(page, 1);
+			page->mapping = NULL;
+			ClearPageActive(page);
+			ClearPageUnevictable(page);
+			put_page(page);
+		}
+
+		local_irq_save(flags);
+		__inc_zone_page_state(new_page, NR_SHMEM_THPS);
+		if (nr_none) {
+			__mod_zone_page_state(zone, NR_FILE_PAGES, nr_none);
+			__mod_zone_page_state(zone, NR_SHMEM, nr_none);
+		}
+		local_irq_restore(flags);
+
+		/*
+		 * Remove pte page tables, so we can re-faulti
+		 * the page as huge.
+		 */
+		retract_page_tables(mapping, start);
+
+		/* Everything is ready, let's unfreeze the new_page */
+		set_page_dirty(new_page);
+		SetPageUptodate(new_page);
+		page_ref_unfreeze(new_page, HPAGE_PMD_NR);
+		mem_cgroup_commit_charge(new_page, memcg, false, true);
+		lru_cache_add_anon(new_page);
+		unlock_page(new_page);
+
+		*hpage = NULL;
+	} else {
+		/* Something went wrong: rollback changes to the radix-tree */
+		shmem_uncharge(mapping->host, nr_none);
+		spin_lock_irq(&mapping->tree_lock);
+		radix_tree_for_each_slot(slot, &mapping->page_tree, &iter,
+				start) {
+			if (iter.index >= end)
+				break;
+			page = list_first_entry_or_null(&pagelist,
+					struct page, lru);
+			if (!page || iter.index < page->index) {
+				if (!nr_none)
+					break;
+				/* Put holes back where they were */
+				radix_tree_replace_slot(slot, NULL);
+				nr_none--;
+				continue;
+			}
+
+			VM_BUG_ON_PAGE(page->index != iter.index, page);
+
+			/* Unfreeze the page. */
+			list_del(&page->lru);
+			page_ref_unfreeze(page, 2);
+			radix_tree_replace_slot(slot, page);
+			spin_unlock_irq(&mapping->tree_lock);
+			putback_lru_page(page);
+			unlock_page(page);
+			spin_lock_irq(&mapping->tree_lock);
+		}
+		VM_BUG_ON(nr_none);
+		spin_unlock_irq(&mapping->tree_lock);
+
+		/* Unfreeze new_page, caller would take care about freeing it */
+		page_ref_unfreeze(new_page, 1);
+		mem_cgroup_cancel_charge(new_page, memcg, true);
+		unlock_page(new_page);
+		new_page->mapping = NULL;
+	}
+out:
+	VM_BUG_ON(!list_empty(&pagelist));
+	/* TODO: tracepoints */
+}
+
+static void khugepaged_scan_shmem(struct mm_struct *mm,
+		struct address_space *mapping,
+		pgoff_t start, struct page **hpage)
+{
+	struct page *page = NULL;
+	struct radix_tree_iter iter;
+	void **slot;
+	int present, swap;
+	int node = NUMA_NO_NODE;
+	int result = SCAN_SUCCEED;
+
+	present = 0;
+	swap = 0;
+	memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
+	rcu_read_lock();
+	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
+		if (iter.index >= start + HPAGE_PMD_NR)
+			break;
+
+		page = radix_tree_deref_slot(slot);
+		if (radix_tree_deref_retry(page)) {
+			slot = radix_tree_iter_retry(&iter);
+			continue;
+		}
+
+		if (radix_tree_exception(page)) {
+			if (++swap > khugepaged_max_ptes_swap) {
+				result = SCAN_EXCEED_SWAP_PTE;
+				break;
+			}
+			continue;
+		}
+
+		if (PageTransCompound(page)) {
+			result = SCAN_PAGE_COMPOUND;
+			break;
+		}
+
+		node = page_to_nid(page);
+		if (khugepaged_scan_abort(node)) {
+			result = SCAN_SCAN_ABORT;
+			break;
+		}
+		khugepaged_node_load[node]++;
+
+		if (!PageLRU(page)) {
+			result = SCAN_PAGE_LRU;
+			break;
+		}
+
+		if (page_count(page) != 1 + page_mapcount(page)) {
+			result = SCAN_PAGE_COUNT;
+			break;
+		}
+
+		/*
+		 * We probably should check if the page is referenced here, but
+		 * nobody would transfer pte_young() to PageReferenced() for us.
+		 * And rmap walk here is just too costly...
+		 */
+
+		present++;
+
+		if (need_resched()) {
+			cond_resched_rcu();
+			slot = radix_tree_iter_next(&iter);
+		}
+	}
+	rcu_read_unlock();
+
+	if (result == SCAN_SUCCEED) {
+		if (present < HPAGE_PMD_NR - khugepaged_max_ptes_none) {
+			result = SCAN_EXCEED_NONE_PTE;
+		} else {
+			node = khugepaged_find_target_node();
+			collapse_shmem(mm, mapping, start, hpage, node);
+		}
+	}
+
+	/* TODO: tracepoints */
+}
+#else
+static void khugepaged_scan_shmem(struct mm_struct *mm,
+		struct address_space *mapping,
+		pgoff_t start, struct page **hpage)
+{
+	BUILD_BUG();
+}
+#endif
+
 static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
 					    struct page **hpage)
 	__releases(&khugepaged_mm_lock)
@@ -1266,6 +1678,8 @@ skip:
 		if (khugepaged_scan.address < hstart)
 			khugepaged_scan.address = hstart;
 		VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
+		if (shmem_file(vma->vm_file) && !shmem_huge_enabled(vma))
+			goto skip;
 
 		while (khugepaged_scan.address < hend) {
 			int ret;
@@ -1276,9 +1690,20 @@ skip:
 			VM_BUG_ON(khugepaged_scan.address < hstart ||
 				  khugepaged_scan.address + HPAGE_PMD_SIZE >
 				  hend);
-			ret = khugepaged_scan_pmd(mm, vma,
-						  khugepaged_scan.address,
-						  hpage);
+			if (shmem_file(vma->vm_file)) {
+				struct file *file = get_file(vma->vm_file);
+				pgoff_t pgoff = linear_page_index(vma,
+						khugepaged_scan.address);
+				up_read(&mm->mmap_sem);
+				ret = 1;
+				khugepaged_scan_shmem(mm, file->f_mapping,
+						pgoff, hpage);
+				fput(file);
+			} else {
+				ret = khugepaged_scan_pmd(mm, vma,
+						khugepaged_scan.address,
+						hpage);
+			}
 			/* move to next address */
 			khugepaged_scan.address += HPAGE_PMD_SIZE;
 			progress += HPAGE_PMD_NR;
diff --git a/mm/shmem.c b/mm/shmem.c
index 6766eeadf48a..a63bc49903e8 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -32,6 +32,7 @@
 #include <linux/export.h>
 #include <linux/swap.h>
 #include <linux/uio.h>
+#include <linux/khugepaged.h>
 
 static struct vfsmount *shm_mnt;
 
@@ -97,16 +98,6 @@ struct shmem_falloc {
 	pgoff_t nr_unswapped;	/* how often writepage refused to swap out */
 };
 
-/* Flag allocation requirements to shmem_getpage */
-enum sgp_type {
-	SGP_READ,	/* don't exceed i_size, don't allocate page */
-	SGP_CACHE,	/* don't exceed i_size, may allocate page */
-	SGP_NOHUGE,	/* like SGP_CACHE, but no huge pages */
-	SGP_HUGE,	/* like SGP_CACHE, huge pages preferred */
-	SGP_WRITE,	/* may exceed i_size, may allocate !Uptodate page */
-	SGP_FALLOC,	/* like SGP_WRITE, but make existing page Uptodate */
-};
-
 #ifdef CONFIG_TMPFS
 static unsigned long shmem_default_max_blocks(void)
 {
@@ -126,7 +117,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
 		struct page **pagep, enum sgp_type sgp,
 		gfp_t gfp, struct mm_struct *fault_mm, int *fault_type);
 
-static inline int shmem_getpage(struct inode *inode, pgoff_t index,
+int shmem_getpage(struct inode *inode, pgoff_t index,
 		struct page **pagep, enum sgp_type sgp)
 {
 	return shmem_getpage_gfp(inode, index, pagep, sgp,
@@ -1899,6 +1890,11 @@ static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	file_accessed(file);
 	vma->vm_ops = &shmem_vm_ops;
+	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
+			((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
+			(vma->vm_end & HPAGE_PMD_MASK)) {
+		khugepaged_enter(vma, vma->vm_flags);
+	}
 	return 0;
 }
 
@@ -3801,6 +3797,37 @@ static ssize_t shmem_enabled_store(struct kobject *kobj,
 
 struct kobj_attribute shmem_enabled_attr =
 	__ATTR(shmem_enabled, 0644, shmem_enabled_show, shmem_enabled_store);
+
+bool shmem_huge_enabled(struct vm_area_struct *vma)
+{
+	struct inode *inode = file_inode(vma->vm_file);
+	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
+	loff_t i_size;
+	pgoff_t off;
+
+	if (shmem_huge == SHMEM_HUGE_FORCE)
+		return true;
+	if (shmem_huge == SHMEM_HUGE_DENY)
+		return false;
+	switch (sbinfo->huge) {
+		case SHMEM_HUGE_NEVER:
+			return false;
+		case SHMEM_HUGE_ALWAYS:
+			return true;
+		case SHMEM_HUGE_WITHIN_SIZE:
+			off = round_up(vma->vm_pgoff, HPAGE_PMD_NR);
+			i_size = round_up(i_size_read(inode), PAGE_SIZE);
+			if (i_size >= HPAGE_PMD_SIZE &&
+					i_size >> PAGE_SHIFT >= off)
+				return true;
+		case SHMEM_HUGE_ADVISE:
+			/* TODO: implement fadvise() hints */
+			return (vma->vm_flags & VM_HUGEPAGE);
+		default:
+			VM_BUG_ON(1);
+			return false;
+	}
+}
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
 
 #else /* !CONFIG_SHMEM */
@@ -3980,6 +4007,13 @@ int shmem_zero_setup(struct vm_area_struct *vma)
 		fput(vma->vm_file);
 	vma->vm_file = file;
 	vma->vm_ops = &shmem_vm_ops;
+
+	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
+			((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
+			(vma->vm_end & HPAGE_PMD_MASK)) {
+		khugepaged_enter(vma, vma->vm_flags);
+	}
+
 	return 0;
 }
 
-- 
2.8.1

[toc] | [prev] | [next] | [standalone]

#1416023 — [PATCHv9-rebased 31/32] shmem: split huge pages beyond i_size under memory pressure

Even if user asked to allocate huge pages always (huge=always), we
should be able to free up some memory by splitting pages which are
partly byound i_size if memory presure comes or once we hit limit on
filesystem size (-o size=).

In order to do this we maintain per-superblock list of inodes, which
potentially have huge pages on the border of file size.

Per-fs shrinker can reclaim memory by splitting such pages.

If we hit -ENOSPC during shmem_getpage_gfp(), we try to split a page to
free up space on the filesystem and retry allocation if it succeed.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 include/linux/shmem_fs.h |   6 +-
 mm/shmem.c               | 175 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 180 insertions(+), 1 deletion(-)

diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index 54fa28dfbd89..ff078e7043b6 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -16,8 +16,9 @@ struct shmem_inode_info {
 	unsigned long		flags;
 	unsigned long		alloced;	/* data pages alloced to file */
 	unsigned long		swapped;	/* subtotal assigned to swap */
-	struct shared_policy	policy;		/* NUMA memory alloc policy */
+	struct list_head        shrinklist;     /* shrinkable hpage inodes */
 	struct list_head	swaplist;	/* chain of maybes on swap */
+	struct shared_policy	policy;		/* NUMA memory alloc policy */
 	struct simple_xattrs	xattrs;		/* list of xattrs */
 	struct inode		vfs_inode;
 };
@@ -33,6 +34,9 @@ struct shmem_sb_info {
 	kuid_t uid;		    /* Mount uid for root directory */
 	kgid_t gid;		    /* Mount gid for root directory */
 	struct mempolicy *mpol;     /* default memory policy for mappings */
+	spinlock_t shrinklist_lock;   /* Protects shrinklist */
+	struct list_head shrinklist;  /* List of shinkable inodes */
+	unsigned long shrinklist_len; /* Length of shrinklist */
 };
 
 static inline struct shmem_inode_info *SHMEM_I(struct inode *inode)
diff --git a/mm/shmem.c b/mm/shmem.c
index 71d9b2cd5cfb..2848d216bccc 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -188,6 +188,7 @@ static const struct inode_operations shmem_inode_operations;
 static const struct inode_operations shmem_dir_inode_operations;
 static const struct inode_operations shmem_special_inode_operations;
 static const struct vm_operations_struct shmem_vm_ops;
+static struct file_system_type shmem_fs_type;
 
 static LIST_HEAD(shmem_swaplist);
 static DEFINE_MUTEX(shmem_swaplist_mutex);
@@ -406,10 +407,122 @@ static const char *shmem_format_huge(int huge)
 	}
 }
 
+static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
+		struct shrink_control *sc, unsigned long nr_to_split)
+{
+	LIST_HEAD(list), *pos, *next;
+	struct inode *inode;
+	struct shmem_inode_info *info;
+	struct page *page;
+	unsigned long batch = sc ? sc->nr_to_scan : 128;
+	int removed = 0, split = 0;
+
+	if (list_empty(&sbinfo->shrinklist))
+		return SHRINK_STOP;
+
+	spin_lock(&sbinfo->shrinklist_lock);
+	list_for_each_safe(pos, next, &sbinfo->shrinklist) {
+		info = list_entry(pos, struct shmem_inode_info, shrinklist);
+
+		/* pin the inode */
+		inode = igrab(&info->vfs_inode);
+
+		/* inode is about to be evicted */
+		if (!inode) {
+			list_del_init(&info->shrinklist);
+			removed++;
+			goto next;
+		}
+
+		/* Check if there's anything to gain */
+		if (round_up(inode->i_size, PAGE_SIZE) ==
+				round_up(inode->i_size, HPAGE_PMD_SIZE)) {
+			list_del_init(&info->shrinklist);
+			removed++;
+			iput(inode);
+			goto next;
+		}
+
+		list_move(&info->shrinklist, &list);
+next:
+		if (!--batch)
+			break;
+	}
+	spin_unlock(&sbinfo->shrinklist_lock);
+
+	list_for_each_safe(pos, next, &list) {
+		int ret;
+
+		info = list_entry(pos, struct shmem_inode_info, shrinklist);
+		inode = &info->vfs_inode;
+
+		if (nr_to_split && split >= nr_to_split) {
+			iput(inode);
+			continue;
+		}
+
+		page = find_lock_page(inode->i_mapping,
+				(inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT);
+		if (!page)
+			goto drop;
+
+		if (!PageTransHuge(page)) {
+			unlock_page(page);
+			put_page(page);
+			goto drop;
+		}
+
+		ret = split_huge_page(page);
+		unlock_page(page);
+		put_page(page);
+
+		if (ret) {
+			/* split failed: leave it on the list */
+			iput(inode);
+			continue;
+		}
+
+		split++;
+drop:
+		list_del_init(&info->shrinklist);
+		removed++;
+		iput(inode);
+	}
+
+	spin_lock(&sbinfo->shrinklist_lock);
+	list_splice_tail(&list, &sbinfo->shrinklist);
+	sbinfo->shrinklist_len -= removed;
+	spin_unlock(&sbinfo->shrinklist_lock);
+
+	return split;
+}
+
+static long shmem_unused_huge_scan(struct super_block *sb,
+		struct shrink_control *sc)
+{
+	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+
+	if (!READ_ONCE(sbinfo->shrinklist_len))
+		return SHRINK_STOP;
+
+	return shmem_unused_huge_shrink(sbinfo, sc, 0);
+}
+
+static long shmem_unused_huge_count(struct super_block *sb,
+		struct shrink_control *sc)
+{
+	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+	return READ_ONCE(sbinfo->shrinklist_len);
+}
 #else /* !CONFIG_TRANSPARENT_HUGE_PAGECACHE */
 
 #define shmem_huge SHMEM_HUGE_DENY
 
+static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
+		struct shrink_control *sc, unsigned long nr_to_split)
+{
+	return 0;
+}
 #endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE */
 
 /*
@@ -843,6 +956,7 @@ static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
 	struct shmem_inode_info *info = SHMEM_I(inode);
+	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
 	int error;
 
 	error = inode_change_ok(inode, attr);
@@ -878,6 +992,20 @@ static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
 			if (oldsize > holebegin)
 				unmap_mapping_range(inode->i_mapping,
 							holebegin, 0, 1);
+
+			/*
+			 * Part of the huge page can be beyond i_size: subject
+			 * to shrink under memory pressure.
+			 */
+			if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
+				spin_lock(&sbinfo->shrinklist_lock);
+				if (list_empty(&info->shrinklist)) {
+					list_add_tail(&info->shrinklist,
+							&sbinfo->shrinklist);
+					sbinfo->shrinklist_len++;
+				}
+				spin_unlock(&sbinfo->shrinklist_lock);
+			}
 		}
 	}
 
@@ -890,11 +1018,20 @@ static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
 static void shmem_evict_inode(struct inode *inode)
 {
 	struct shmem_inode_info *info = SHMEM_I(inode);
+	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
 
 	if (inode->i_mapping->a_ops == &shmem_aops) {
 		shmem_unacct_size(info->flags, inode->i_size);
 		inode->i_size = 0;
 		shmem_truncate_range(inode, 0, (loff_t)-1);
+		if (!list_empty(&info->shrinklist)) {
+			spin_lock(&sbinfo->shrinklist_lock);
+			if (!list_empty(&info->shrinklist)) {
+				list_del_init(&info->shrinklist);
+				sbinfo->shrinklist_len--;
+			}
+			spin_unlock(&sbinfo->shrinklist_lock);
+		}
 		if (!list_empty(&info->swaplist)) {
 			mutex_lock(&shmem_swaplist_mutex);
 			list_del_init(&info->swaplist);
@@ -1563,8 +1700,23 @@ alloc_nohuge:		page = shmem_alloc_and_acct_page(gfp, info, sbinfo,
 					index, false);
 		}
 		if (IS_ERR(page)) {
+			int retry = 5;
 			error = PTR_ERR(page);
 			page = NULL;
+			if (error != -ENOSPC)
+				goto failed;
+			/*
+			 * Try to reclaim some spece by splitting a huge page
+			 * beyond i_size on the filesystem.
+			 */
+			while (retry--) {
+				int ret;
+				ret = shmem_unused_huge_shrink(sbinfo, NULL, 1);
+				if (ret == SHRINK_STOP)
+					break;
+				if (ret)
+					goto alloc_nohuge;
+			}
 			goto failed;
 		}
 
@@ -1603,6 +1755,22 @@ alloc_nohuge:		page = shmem_alloc_and_acct_page(gfp, info, sbinfo,
 		spin_unlock_irq(&info->lock);
 		alloced = true;
 
+		if (PageTransHuge(page) &&
+				DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) <
+				hindex + HPAGE_PMD_NR - 1) {
+			/*
+			 * Part of the huge page is beyond i_size: subject
+			 * to shrink under memory pressure.
+			 */
+			spin_lock(&sbinfo->shrinklist_lock);
+			if (list_empty(&info->shrinklist)) {
+				list_add_tail(&info->shrinklist,
+						&sbinfo->shrinklist);
+				sbinfo->shrinklist_len++;
+			}
+			spin_unlock(&sbinfo->shrinklist_lock);
+		}
+
 		/*
 		 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
 		 */
@@ -1920,6 +2088,7 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
 		spin_lock_init(&info->lock);
 		info->seals = F_SEAL_SEAL;
 		info->flags = flags & VM_NORESERVE;
+		INIT_LIST_HEAD(&info->shrinklist);
 		INIT_LIST_HEAD(&info->swaplist);
 		simple_xattrs_init(&info->xattrs);
 		cache_no_acl(inode);
@@ -3516,6 +3685,8 @@ int shmem_fill_super(struct super_block *sb, void *data, int silent)
 	if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
 		goto failed;
 	sbinfo->free_inodes = sbinfo->max_inodes;
+	spin_lock_init(&sbinfo->shrinklist_lock);
+	INIT_LIST_HEAD(&sbinfo->shrinklist);
 
 	sb->s_maxbytes = MAX_LFS_FILESIZE;
 	sb->s_blocksize = PAGE_SIZE;
@@ -3678,6 +3849,10 @@ static const struct super_operations shmem_ops = {
 	.evict_inode	= shmem_evict_inode,
 	.drop_inode	= generic_delete_inode,
 	.put_super	= shmem_put_super,
+#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
+	.nr_cached_objects	= shmem_unused_huge_count,
+	.free_cached_objects	= shmem_unused_huge_scan,
+#endif
 };
 
 static const struct vm_operations_struct shmem_vm_ops = {
-- 
2.8.1

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#1416025 — [PATCHv9-rebased 02/32] mm: do not pass mm_struct into handle_mm_fault

We always have vma->vm_mm around.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 arch/alpha/mm/fault.c         |  2 +-
 arch/arc/mm/fault.c           |  2 +-
 arch/arm/mm/fault.c           |  2 +-
 arch/arm64/mm/fault.c         |  2 +-
 arch/avr32/mm/fault.c         |  2 +-
 arch/cris/mm/fault.c          |  2 +-
 arch/frv/mm/fault.c           |  2 +-
 arch/hexagon/mm/vm_fault.c    |  2 +-
 arch/ia64/mm/fault.c          |  2 +-
 arch/m32r/mm/fault.c          |  2 +-
 arch/m68k/mm/fault.c          |  2 +-
 arch/metag/mm/fault.c         |  2 +-
 arch/microblaze/mm/fault.c    |  2 +-
 arch/mips/mm/fault.c          |  2 +-
 arch/mn10300/mm/fault.c       |  2 +-
 arch/nios2/mm/fault.c         |  2 +-
 arch/openrisc/mm/fault.c      |  2 +-
 arch/parisc/mm/fault.c        |  2 +-
 arch/powerpc/mm/copro_fault.c |  2 +-
 arch/powerpc/mm/fault.c       |  2 +-
 arch/s390/mm/fault.c          |  2 +-
 arch/score/mm/fault.c         |  2 +-
 arch/sh/mm/fault.c            |  2 +-
 arch/sparc/mm/fault_32.c      |  4 ++--
 arch/sparc/mm/fault_64.c      |  2 +-
 arch/tile/mm/fault.c          |  2 +-
 arch/um/kernel/trap.c         |  2 +-
 arch/unicore32/mm/fault.c     |  2 +-
 arch/x86/mm/fault.c           |  2 +-
 arch/xtensa/mm/fault.c        |  2 +-
 drivers/iommu/amd_iommu_v2.c  |  3 +--
 drivers/iommu/intel-svm.c     |  2 +-
 include/linux/mm.h            |  9 ++++-----
 mm/gup.c                      |  5 ++---
 mm/ksm.c                      |  5 ++---
 mm/memory.c                   | 13 +++++++------
 36 files changed, 48 insertions(+), 51 deletions(-)

diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
index 4a905bd667e2..83e9eee57a55 100644
--- a/arch/alpha/mm/fault.c
+++ b/arch/alpha/mm/fault.c
@@ -147,7 +147,7 @@ retry:
 	/* If for any reason at all we couldn't handle the fault,
 	   make sure we exit gracefully rather than endlessly redo
 	   the fault.  */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return;
diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index af63f4a13e60..e94e5aa33985 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -137,7 +137,7 @@ good_area:
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	/* If Pagefault was interrupted by SIGKILL, exit page fault "early" */
 	if (unlikely(fatal_signal_pending(current))) {
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index ad5841856007..3a2e678b8d30 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -243,7 +243,7 @@ good_area:
 		goto out;
 	}
 
-	return handle_mm_fault(mm, vma, addr & PAGE_MASK, flags);
+	return handle_mm_fault(vma, addr & PAGE_MASK, flags);
 
 check_stack:
 	/* Don't allow expansion below FIRST_USER_ADDRESS */
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 5954881a35ac..170bef41d299 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -233,7 +233,7 @@ good_area:
 		goto out;
 	}
 
-	return handle_mm_fault(mm, vma, addr & PAGE_MASK, mm_flags);
+	return handle_mm_fault(vma, addr & PAGE_MASK, mm_flags);
 
 check_stack:
 	if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
diff --git a/arch/avr32/mm/fault.c b/arch/avr32/mm/fault.c
index c03533937a9f..a4b7edac8f10 100644
--- a/arch/avr32/mm/fault.c
+++ b/arch/avr32/mm/fault.c
@@ -134,7 +134,7 @@ good_area:
 	 * sure we exit gracefully rather than endlessly redo the
 	 * fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return;
diff --git a/arch/cris/mm/fault.c b/arch/cris/mm/fault.c
index 3066d40a6db1..112ef26c7f2e 100644
--- a/arch/cris/mm/fault.c
+++ b/arch/cris/mm/fault.c
@@ -168,7 +168,7 @@ retry:
 	 * the fault.
 	 */
 
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return;
diff --git a/arch/frv/mm/fault.c b/arch/frv/mm/fault.c
index 61d99767fe16..614a46c413d2 100644
--- a/arch/frv/mm/fault.c
+++ b/arch/frv/mm/fault.c
@@ -164,7 +164,7 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, ear0, flags);
+	fault = handle_mm_fault(vma, ear0, flags);
 	if (unlikely(fault & VM_FAULT_ERROR)) {
 		if (fault & VM_FAULT_OOM)
 			goto out_of_memory;
diff --git a/arch/hexagon/mm/vm_fault.c b/arch/hexagon/mm/vm_fault.c
index 8704c9320032..bd7c251e2bce 100644
--- a/arch/hexagon/mm/vm_fault.c
+++ b/arch/hexagon/mm/vm_fault.c
@@ -101,7 +101,7 @@ good_area:
 		break;
 	}
 
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return;
diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
index 70b40d1205a6..fa6ad95e992e 100644
--- a/arch/ia64/mm/fault.c
+++ b/arch/ia64/mm/fault.c
@@ -159,7 +159,7 @@ retry:
 	 * sure we exit gracefully rather than endlessly redo the
 	 * fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return;
diff --git a/arch/m32r/mm/fault.c b/arch/m32r/mm/fault.c
index 8f9875b7933d..a3785d3644c2 100644
--- a/arch/m32r/mm/fault.c
+++ b/arch/m32r/mm/fault.c
@@ -196,7 +196,7 @@ good_area:
 	 */
 	addr = (address & PAGE_MASK);
 	set_thread_fault_code(error_code);
-	fault = handle_mm_fault(mm, vma, addr, flags);
+	fault = handle_mm_fault(vma, addr, flags);
 	if (unlikely(fault & VM_FAULT_ERROR)) {
 		if (fault & VM_FAULT_OOM)
 			goto out_of_memory;
diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c
index 6a94cdd0c830..bd66a0b20c6b 100644
--- a/arch/m68k/mm/fault.c
+++ b/arch/m68k/mm/fault.c
@@ -136,7 +136,7 @@ good_area:
 	 * the fault.
 	 */
 
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 	pr_debug("handle_mm_fault returns %d\n", fault);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
diff --git a/arch/metag/mm/fault.c b/arch/metag/mm/fault.c
index f57edca63609..372783a67dda 100644
--- a/arch/metag/mm/fault.c
+++ b/arch/metag/mm/fault.c
@@ -133,7 +133,7 @@ good_area:
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return 0;
diff --git a/arch/microblaze/mm/fault.c b/arch/microblaze/mm/fault.c
index 177dfc003643..abb678ccde6f 100644
--- a/arch/microblaze/mm/fault.c
+++ b/arch/microblaze/mm/fault.c
@@ -216,7 +216,7 @@ good_area:
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return;
diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index 4b88fa031891..9560ad731120 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -153,7 +153,7 @@ good_area:
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return;
diff --git a/arch/mn10300/mm/fault.c b/arch/mn10300/mm/fault.c
index 4a1d181ed32f..f23781d6bbb3 100644
--- a/arch/mn10300/mm/fault.c
+++ b/arch/mn10300/mm/fault.c
@@ -254,7 +254,7 @@ good_area:
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return;
diff --git a/arch/nios2/mm/fault.c b/arch/nios2/mm/fault.c
index b51878b0c6b8..affc4eb3f89e 100644
--- a/arch/nios2/mm/fault.c
+++ b/arch/nios2/mm/fault.c
@@ -131,7 +131,7 @@ good_area:
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return;
diff --git a/arch/openrisc/mm/fault.c b/arch/openrisc/mm/fault.c
index 230ac20ae794..e94cd225e816 100644
--- a/arch/openrisc/mm/fault.c
+++ b/arch/openrisc/mm/fault.c
@@ -163,7 +163,7 @@ good_area:
 	 * the fault.
 	 */
 
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return;
diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
index 16dbe81c97c9..163af2c31d76 100644
--- a/arch/parisc/mm/fault.c
+++ b/arch/parisc/mm/fault.c
@@ -239,7 +239,7 @@ good_area:
 	 * fault.
 	 */
 
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return;
diff --git a/arch/powerpc/mm/copro_fault.c b/arch/powerpc/mm/copro_fault.c
index 6527882ce05e..bb0354222b11 100644
--- a/arch/powerpc/mm/copro_fault.c
+++ b/arch/powerpc/mm/copro_fault.c
@@ -75,7 +75,7 @@ int copro_handle_mm_fault(struct mm_struct *mm, unsigned long ea,
 	}
 
 	ret = 0;
-	*flt = handle_mm_fault(mm, vma, ea, is_write ? FAULT_FLAG_WRITE : 0);
+	*flt = handle_mm_fault(vma, ea, is_write ? FAULT_FLAG_WRITE : 0);
 	if (unlikely(*flt & VM_FAULT_ERROR)) {
 		if (*flt & VM_FAULT_OOM) {
 			ret = -ENOMEM;
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index a67c6d781c52..a4db22f65021 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -429,7 +429,7 @@ good_area:
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 	if (unlikely(fault & (VM_FAULT_RETRY|VM_FAULT_ERROR))) {
 		if (fault & VM_FAULT_SIGSEGV)
 			goto bad_area;
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 19288c1b36d3..6c47488745ae 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -456,7 +456,7 @@ retry:
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 	/* No reason to continue if interrupted by SIGKILL. */
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
 		fault = VM_FAULT_SIGNAL;
diff --git a/arch/score/mm/fault.c b/arch/score/mm/fault.c
index 37a6c2e0e969..995b71e4db4b 100644
--- a/arch/score/mm/fault.c
+++ b/arch/score/mm/fault.c
@@ -111,7 +111,7 @@ good_area:
 	* make sure we exit gracefully rather than endlessly redo
 	* the fault.
 	*/
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 	if (unlikely(fault & VM_FAULT_ERROR)) {
 		if (fault & VM_FAULT_OOM)
 			goto out_of_memory;
diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 79d8276377d1..9bf876780cef 100644
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c
@@ -487,7 +487,7 @@ good_area:
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if (unlikely(fault & (VM_FAULT_RETRY | VM_FAULT_ERROR)))
 		if (mm_fault_error(regs, error_code, address, fault))
diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
index b6c559cbd64d..4714061d6cd3 100644
--- a/arch/sparc/mm/fault_32.c
+++ b/arch/sparc/mm/fault_32.c
@@ -241,7 +241,7 @@ good_area:
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return;
@@ -411,7 +411,7 @@ good_area:
 		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 			goto bad_area;
 	}
-	switch (handle_mm_fault(mm, vma, address, flags)) {
+	switch (handle_mm_fault(vma, address, flags)) {
 	case VM_FAULT_SIGBUS:
 	case VM_FAULT_OOM:
 		goto do_sigbus;
diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
index cb841a33da59..6c43b924a7a2 100644
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -436,7 +436,7 @@ good_area:
 			goto bad_area;
 	}
 
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		goto exit_exception;
diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c
index 26734214818c..beba986589e5 100644
--- a/arch/tile/mm/fault.c
+++ b/arch/tile/mm/fault.c
@@ -434,7 +434,7 @@ good_area:
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return 0;
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index 98783dd0fa2e..ad8f206ab5e8 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -73,7 +73,7 @@ good_area:
 	do {
 		int fault;
 
-		fault = handle_mm_fault(mm, vma, address, flags);
+		fault = handle_mm_fault(vma, address, flags);
 
 		if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 			goto out_nosemaphore;
diff --git a/arch/unicore32/mm/fault.c b/arch/unicore32/mm/fault.c
index 2ec3d3adcefc..6c7f70bcaae3 100644
--- a/arch/unicore32/mm/fault.c
+++ b/arch/unicore32/mm/fault.c
@@ -194,7 +194,7 @@ good_area:
 	 * If for any reason at all we couldn't handle the fault, make
 	 * sure we exit gracefully rather than endlessly redo the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, flags);
+	fault = handle_mm_fault(vma, addr & PAGE_MASK, flags);
 	return fault;
 
 check_stack:
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 7d1fa7cd2374..48c7a68f6171 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1353,7 +1353,7 @@ good_area:
 	 * the fault.  Since we never set FAULT_FLAG_RETRY_NOWAIT, if
 	 * we get VM_FAULT_RETRY back, the mmap_sem has been unlocked.
 	 */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 	major |= fault & VM_FAULT_MAJOR;
 
 	/*
diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c
index 7f4a1fdb1502..2725e08ef353 100644
--- a/arch/xtensa/mm/fault.c
+++ b/arch/xtensa/mm/fault.c
@@ -110,7 +110,7 @@ good_area:
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, flags);
+	fault = handle_mm_fault(vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return;
diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
index 56999d2fac07..fbdaf81ae925 100644
--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -538,8 +538,7 @@ static void do_fault(struct work_struct *work)
 	if (access_error(vma, fault))
 		goto out;
 
-	ret = handle_mm_fault(mm, vma, address, flags);
-
+	ret = handle_mm_fault(vma, address, flags);
 out:
 	up_read(&mm->mmap_sem);
 
diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
index d9939fa9b588..8ebb3530afa7 100644
--- a/drivers/iommu/intel-svm.c
+++ b/drivers/iommu/intel-svm.c
@@ -583,7 +583,7 @@ static irqreturn_t prq_event_thread(int irq, void *d)
 		if (access_error(vma, req))
 			goto invalid;
 
-		ret = handle_mm_fault(svm->mm, vma, address,
+		ret = handle_mm_fault(vma, address,
 				      req->wr_req ? FAULT_FLAG_WRITE : 0);
 		if (ret & VM_FAULT_ERROR)
 			goto invalid;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index da08140c0542..4b642148cccd 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1215,15 +1215,14 @@ int generic_error_remove_page(struct address_space *mapping, struct page *page);
 int invalidate_inode_page(struct page *page);
 
 #ifdef CONFIG_MMU
-extern int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
-			unsigned long address, unsigned int flags);
+extern int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
+		unsigned int flags);
 extern int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
 			    unsigned long address, unsigned int fault_flags,
 			    bool *unlocked);
 #else
-static inline int handle_mm_fault(struct mm_struct *mm,
-			struct vm_area_struct *vma, unsigned long address,
-			unsigned int flags)
+static inline int handle_mm_fault(struct vm_area_struct *vma,
+		unsigned long address, unsigned int flags)
 {
 	/* should never happen if there's no MMU */
 	BUG();
diff --git a/mm/gup.c b/mm/gup.c
index dee142e100f4..9671e29f8ffd 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -352,7 +352,6 @@ unmap:
 static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
 		unsigned long address, unsigned int *flags, int *nonblocking)
 {
-	struct mm_struct *mm = vma->vm_mm;
 	unsigned int fault_flags = 0;
 	int ret;
 
@@ -377,7 +376,7 @@ static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
 		fault_flags |= FAULT_FLAG_TRIED;
 	}
 
-	ret = handle_mm_fault(mm, vma, address, fault_flags);
+	ret = handle_mm_fault(vma, address, fault_flags);
 	if (ret & VM_FAULT_ERROR) {
 		if (ret & VM_FAULT_OOM)
 			return -ENOMEM;
@@ -692,7 +691,7 @@ retry:
 	if (!vma_permits_fault(vma, fault_flags))
 		return -EFAULT;
 
-	ret = handle_mm_fault(mm, vma, address, fault_flags);
+	ret = handle_mm_fault(vma, address, fault_flags);
 	major |= ret & VM_FAULT_MAJOR;
 	if (ret & VM_FAULT_ERROR) {
 		if (ret & VM_FAULT_OOM)
diff --git a/mm/ksm.c b/mm/ksm.c
index 35b8aef867a9..73d43bafd9fb 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -376,9 +376,8 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr)
 		if (IS_ERR_OR_NULL(page))
 			break;
 		if (PageKsm(page))
-			ret = handle_mm_fault(vma->vm_mm, vma, addr,
-							FAULT_FLAG_WRITE |
-							FAULT_FLAG_REMOTE);
+			ret = handle_mm_fault(vma, addr,
+					FAULT_FLAG_WRITE | FAULT_FLAG_REMOTE);
 		else
 			ret = VM_FAULT_WRITE;
 		put_page(page);
diff --git a/mm/memory.c b/mm/memory.c
index bd89eaf2c77e..c981e6a5bdc4 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3442,9 +3442,10 @@ unlock:
  * The mmap_sem may have been released depending on flags and our
  * return value.  See filemap_fault() and __lock_page_or_retry().
  */
-static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
-			     unsigned long address, unsigned int flags)
+static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
+		unsigned int flags)
 {
+	struct mm_struct *mm = vma->vm_mm;
 	pgd_t *pgd;
 	pud_t *pud;
 	pmd_t *pmd;
@@ -3531,15 +3532,15 @@ static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
  * The mmap_sem may have been released depending on flags and our
  * return value.  See filemap_fault() and __lock_page_or_retry().
  */
-int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
-		    unsigned long address, unsigned int flags)
+int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
+		unsigned int flags)
 {
 	int ret;
 
 	__set_current_state(TASK_RUNNING);
 
 	count_vm_event(PGFAULT);
-	mem_cgroup_count_vm_event(mm, PGFAULT);
+	mem_cgroup_count_vm_event(vma->vm_mm, PGFAULT);
 
 	/* do counter updates before entering really critical section. */
 	check_sync_rss_stat(current);
@@ -3551,7 +3552,7 @@ int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 	if (flags & FAULT_FLAG_USER)
 		mem_cgroup_oom_enable();
 
-	ret = __handle_mm_fault(mm, vma, address, flags);
+	ret = __handle_mm_fault(vma, address, flags);
 
 	if (flags & FAULT_FLAG_USER) {
 		mem_cgroup_oom_disable();
-- 
2.8.1

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#1416026 — [PATCHv9-rebased 21/32] mm, rmap: account shmem thp pages

Let's add ShmemHugePages and ShmemPmdMapped fields into meminfo and
smaps. It indicates how many times we allocate and map shmem THP.

NR_ANON_TRANSPARENT_HUGEPAGES is renamed to NR_ANON_THPS.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 drivers/base/node.c    | 13 +++++++++----
 fs/proc/meminfo.c      |  7 +++++--
 fs/proc/task_mmu.c     | 10 +++++++++-
 include/linux/mmzone.h |  4 +++-
 mm/huge_memory.c       |  4 +++-
 mm/page_alloc.c        | 19 +++++++++++++++++++
 mm/rmap.c              | 14 ++++++++------
 mm/vmstat.c            |  2 ++
 8 files changed, 58 insertions(+), 15 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 560751bad294..51c7db2c4ee2 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -113,6 +113,8 @@ static ssize_t node_read_meminfo(struct device *dev,
 		       "Node %d SUnreclaim:     %8lu kB\n"
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 		       "Node %d AnonHugePages:  %8lu kB\n"
+		       "Node %d ShmemHugePages: %8lu kB\n"
+		       "Node %d ShmemPmdMapped: %8lu kB\n"
 #endif
 			,
 		       nid, K(node_page_state(nid, NR_FILE_DIRTY)),
@@ -131,10 +133,13 @@ static ssize_t node_read_meminfo(struct device *dev,
 				node_page_state(nid, NR_SLAB_UNRECLAIMABLE)),
 		       nid, K(node_page_state(nid, NR_SLAB_RECLAIMABLE)),
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-		       nid, K(node_page_state(nid, NR_SLAB_UNRECLAIMABLE))
-			, nid,
-			K(node_page_state(nid, NR_ANON_TRANSPARENT_HUGEPAGES) *
-			HPAGE_PMD_NR));
+		       nid, K(node_page_state(nid, NR_SLAB_UNRECLAIMABLE)),
+		       nid, K(node_page_state(nid, NR_ANON_THPS) *
+				       HPAGE_PMD_NR),
+		       nid, K(node_page_state(nid, NR_SHMEM_THPS) *
+				       HPAGE_PMD_NR),
+		       nid, K(node_page_state(nid, NR_SHMEM_PMDMAPPED) *
+				       HPAGE_PMD_NR));
 #else
 		       nid, K(node_page_state(nid, NR_SLAB_UNRECLAIMABLE)));
 #endif
diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
index 83720460c5bc..cf301a9ef512 100644
--- a/fs/proc/meminfo.c
+++ b/fs/proc/meminfo.c
@@ -105,6 +105,8 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
 #endif
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 		"AnonHugePages:  %8lu kB\n"
+		"ShmemHugePages: %8lu kB\n"
+		"ShmemPmdMapped: %8lu kB\n"
 #endif
 #ifdef CONFIG_CMA
 		"CmaTotal:       %8lu kB\n"
@@ -162,8 +164,9 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
 		, atomic_long_read(&num_poisoned_pages) << (PAGE_SHIFT - 10)
 #endif
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-		, K(global_page_state(NR_ANON_TRANSPARENT_HUGEPAGES) *
-		   HPAGE_PMD_NR)
+		, K(global_page_state(NR_ANON_THPS) * HPAGE_PMD_NR)
+		, K(global_page_state(NR_SHMEM_THPS) * HPAGE_PMD_NR)
+		, K(global_page_state(NR_SHMEM_PMDMAPPED) * HPAGE_PMD_NR)
 #endif
 #ifdef CONFIG_CMA
 		, K(totalcma_pages)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 4648c7f63ae2..187d84ef9de9 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -448,6 +448,7 @@ struct mem_size_stats {
 	unsigned long referenced;
 	unsigned long anonymous;
 	unsigned long anonymous_thp;
+	unsigned long shmem_thp;
 	unsigned long swap;
 	unsigned long shared_hugetlb;
 	unsigned long private_hugetlb;
@@ -576,7 +577,12 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
 	page = follow_trans_huge_pmd(vma, addr, pmd, FOLL_DUMP);
 	if (IS_ERR_OR_NULL(page))
 		return;
-	mss->anonymous_thp += HPAGE_PMD_SIZE;
+	if (PageAnon(page))
+		mss->anonymous_thp += HPAGE_PMD_SIZE;
+	else if (PageSwapBacked(page))
+		mss->shmem_thp += HPAGE_PMD_SIZE;
+	else
+		VM_BUG_ON_PAGE(1, page);
 	smaps_account(mss, page, true, pmd_young(*pmd), pmd_dirty(*pmd));
 }
 #else
@@ -770,6 +776,7 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
 		   "Referenced:     %8lu kB\n"
 		   "Anonymous:      %8lu kB\n"
 		   "AnonHugePages:  %8lu kB\n"
+		   "ShmemPmdMapped: %8lu kB\n"
 		   "Shared_Hugetlb: %8lu kB\n"
 		   "Private_Hugetlb: %7lu kB\n"
 		   "Swap:           %8lu kB\n"
@@ -787,6 +794,7 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
 		   mss.referenced >> 10,
 		   mss.anonymous >> 10,
 		   mss.anonymous_thp >> 10,
+		   mss.shmem_thp >> 10,
 		   mss.shared_hugetlb >> 10,
 		   mss.private_hugetlb >> 10,
 		   mss.swap >> 10,
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 54df45c03ba2..30277502ba3d 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -154,7 +154,9 @@ enum zone_stat_item {
 	WORKINGSET_REFAULT,
 	WORKINGSET_ACTIVATE,
 	WORKINGSET_NODERECLAIM,
-	NR_ANON_TRANSPARENT_HUGEPAGES,
+	NR_ANON_THPS,
+	NR_SHMEM_THPS,
+	NR_SHMEM_PMDMAPPED,
 	NR_FREE_CMA_PAGES,
 	NR_VM_ZONE_STAT_ITEMS };
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 28e7d963cc1f..ada33b395f24 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3074,7 +3074,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 
 	if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
 		/* Last compound_mapcount is gone. */
-		__dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
+		__dec_zone_page_state(page, NR_ANON_THPS);
 		if (TestClearPageDoubleMap(page)) {
 			/* No need in mapcount reference anymore */
 			for (i = 0; i < HPAGE_PMD_NR; i++)
@@ -3553,6 +3553,8 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 			pgdata->split_queue_len--;
 			list_del(page_deferred_list(head));
 		}
+		if (mapping)
+			__dec_zone_page_state(page, NR_SHMEM_THPS);
 		spin_unlock(&pgdata->split_queue_lock);
 		__split_huge_page(page, list, flags);
 		ret = 0;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e32ff3abe9da..4ea7137e5108 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4309,6 +4309,9 @@ void show_free_areas(unsigned int filter)
 		" unevictable:%lu dirty:%lu writeback:%lu unstable:%lu\n"
 		" slab_reclaimable:%lu slab_unreclaimable:%lu\n"
 		" mapped:%lu shmem:%lu pagetables:%lu bounce:%lu\n"
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+		" anon_thp: %lu shmem_thp: %lu shmem_pmdmapped: %lu\n"
+#endif
 		" free:%lu free_pcp:%lu free_cma:%lu\n",
 		global_page_state(NR_ACTIVE_ANON),
 		global_page_state(NR_INACTIVE_ANON),
@@ -4326,6 +4329,11 @@ void show_free_areas(unsigned int filter)
 		global_page_state(NR_SHMEM),
 		global_page_state(NR_PAGETABLE),
 		global_page_state(NR_BOUNCE),
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+		global_page_state(NR_ANON_THPS) * HPAGE_PMD_NR,
+		global_page_state(NR_SHMEM_THPS) * HPAGE_PMD_NR,
+		global_page_state(NR_SHMEM_PMDMAPPED) * HPAGE_PMD_NR,
+#endif
 		global_page_state(NR_FREE_PAGES),
 		free_pcp,
 		global_page_state(NR_FREE_CMA_PAGES));
@@ -4360,6 +4368,11 @@ void show_free_areas(unsigned int filter)
 			" writeback:%lukB"
 			" mapped:%lukB"
 			" shmem:%lukB"
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+			" shmem_thp: %lukB"
+			" shmem_pmdmapped: %lukB"
+			" anon_thp: %lukB"
+#endif
 			" slab_reclaimable:%lukB"
 			" slab_unreclaimable:%lukB"
 			" kernel_stack:%lukB"
@@ -4392,6 +4405,12 @@ void show_free_areas(unsigned int filter)
 			K(zone_page_state(zone, NR_WRITEBACK)),
 			K(zone_page_state(zone, NR_FILE_MAPPED)),
 			K(zone_page_state(zone, NR_SHMEM)),
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+			K(zone_page_state(zone, NR_SHMEM_THPS) * HPAGE_PMD_NR),
+			K(zone_page_state(zone, NR_SHMEM_PMDMAPPED)
+					* HPAGE_PMD_NR),
+			K(zone_page_state(zone, NR_ANON_THPS) * HPAGE_PMD_NR),
+#endif
 			K(zone_page_state(zone, NR_SLAB_RECLAIMABLE)),
 			K(zone_page_state(zone, NR_SLAB_UNRECLAIMABLE)),
 			zone_page_state(zone, NR_KERNEL_STACK) *
diff --git a/mm/rmap.c b/mm/rmap.c
index 26e3e784ad75..256e585c67ef 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1215,10 +1215,8 @@ void do_page_add_anon_rmap(struct page *page,
 		 * pte lock(a spinlock) is held, which implies preemption
 		 * disabled.
 		 */
-		if (compound) {
-			__inc_zone_page_state(page,
-					      NR_ANON_TRANSPARENT_HUGEPAGES);
-		}
+		if (compound)
+			__inc_zone_page_state(page, NR_ANON_THPS);
 		__mod_zone_page_state(page_zone(page), NR_ANON_PAGES, nr);
 	}
 	if (unlikely(PageKsm(page)))
@@ -1256,7 +1254,7 @@ void page_add_new_anon_rmap(struct page *page,
 		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
 		/* increment count (starts at -1) */
 		atomic_set(compound_mapcount_ptr(page), 0);
-		__inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
+		__inc_zone_page_state(page, NR_ANON_THPS);
 	} else {
 		/* Anon THP always mapped first with PMD */
 		VM_BUG_ON_PAGE(PageTransCompound(page), page);
@@ -1286,6 +1284,8 @@ void page_add_file_rmap(struct page *page, bool compound)
 		}
 		if (!atomic_inc_and_test(compound_mapcount_ptr(page)))
 			goto out;
+		VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
+		__inc_zone_page_state(page, NR_SHMEM_PMDMAPPED);
 	} else {
 		if (PageTransCompound(page)) {
 			VM_BUG_ON_PAGE(!PageLocked(page), page);
@@ -1324,6 +1324,8 @@ static void page_remove_file_rmap(struct page *page, bool compound)
 		}
 		if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
 			goto out;
+		VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
+		__dec_zone_page_state(page, NR_SHMEM_PMDMAPPED);
 	} else {
 		if (!atomic_add_negative(-1, &page->_mapcount))
 			goto out;
@@ -1357,7 +1359,7 @@ static void page_remove_anon_compound_rmap(struct page *page)
 	if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
 		return;
 
-	__dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
+	__dec_zone_page_state(page, NR_ANON_THPS);
 
 	if (TestClearPageDoubleMap(page)) {
 		/*
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 68693857397c..181e1e52e584 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -745,6 +745,8 @@ const char * const vmstat_text[] = {
 	"workingset_activate",
 	"workingset_nodereclaim",
 	"nr_anon_transparent_hugepages",
+	"nr_shmem_hugepages",
+	"nr_shmem_pmdmapped",
 	"nr_free_cma",
 
 	/* enum writeback_stat_item counters */
-- 
2.8.1

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#1416027 — [PATCHv9-rebased 12/32] thp: prepare change_huge_pmd() for file thp

change_huge_pmd() has assert which is not relvant for file page.
For shared mapping it's perfectly fine to have page table entry
writable, without explicit mkwrite.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 mm/huge_memory.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b4dc62923dd7..c52119eb2998 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1794,7 +1794,8 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
 				entry = pmd_mkwrite(entry);
 			ret = HPAGE_PMD_NR;
 			set_pmd_at(mm, addr, pmd, entry);
-			BUG_ON(!preserve_write && pmd_write(entry));
+			BUG_ON(vma_is_anonymous(vma) && !preserve_write &&
+					pmd_write(entry));
 		}
 		spin_unlock(ptl);
 	}
-- 
2.8.1

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#1416029 — [PATCHv9-rebased 08/32] thp: support file pages in zap_huge_pmd()

split_huge_pmd() for file mappings (and DAX too) is implemented by just
clearing pmd entry as we can re-fill this area from page cache on pte
level later.

This means we don't need deposit page tables when file THP is mapped.
Therefore we shouldn't try to withdraw a page table on zap_huge_pmd()
file THP PMD.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 mm/huge_memory.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 62a8224b8a0b..1ffd53de82ce 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1695,10 +1695,16 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		struct page *page = pmd_page(orig_pmd);
 		page_remove_rmap(page, true);
 		VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
-		add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
 		VM_BUG_ON_PAGE(!PageHead(page), page);
-		pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
-		atomic_long_dec(&tlb->mm->nr_ptes);
+		if (PageAnon(page)) {
+			pgtable_t pgtable;
+			pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
+			pte_free(tlb->mm, pgtable);
+			atomic_long_dec(&tlb->mm->nr_ptes);
+			add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
+		} else {
+			add_mm_counter(tlb->mm, MM_FILEPAGES, -HPAGE_PMD_NR);
+		}
 		spin_unlock(ptl);
 		tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
 	}
-- 
2.8.1

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#1416031 — [PATCHv9-rebased 05/32] rmap: support file thp

Naive approach: on mapping/unmapping the page as compound we update
->_mapcount on each 4k page. That's not efficient, but it's not obvious
how we can optimize this. We can look into optimization later.

PG_double_map optimization doesn't work for file pages since lifecycle
of file pages is different comparing to anon pages: file page can be
mapped again at any time.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 include/linux/rmap.h |  2 +-
 mm/huge_memory.c     | 10 +++++++---
 mm/memory.c          |  4 ++--
 mm/migrate.c         |  2 +-
 mm/rmap.c            | 48 +++++++++++++++++++++++++++++++++++-------------
 mm/util.c            |  6 ++++++
 6 files changed, 52 insertions(+), 20 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 49eb4f8ebac9..5704f101b52e 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -165,7 +165,7 @@ void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
 			   unsigned long, int);
 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *,
 		unsigned long, bool);
-void page_add_file_rmap(struct page *);
+void page_add_file_rmap(struct page *, bool);
 void page_remove_rmap(struct page *, bool);
 
 void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index f2f255610a7c..dcd2229277be 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3315,18 +3315,22 @@ static void __split_huge_page(struct page *page, struct list_head *list)
 
 int total_mapcount(struct page *page)
 {
-	int i, ret;
+	int i, compound, ret;
 
 	VM_BUG_ON_PAGE(PageTail(page), page);
 
 	if (likely(!PageCompound(page)))
 		return atomic_read(&page->_mapcount) + 1;
 
-	ret = compound_mapcount(page);
+	compound = compound_mapcount(page);
 	if (PageHuge(page))
-		return ret;
+		return compound;
+	ret = compound;
 	for (i = 0; i < HPAGE_PMD_NR; i++)
 		ret += atomic_read(&page[i]._mapcount) + 1;
+	/* File pages has compound_mapcount included in _mapcount */
+	if (!PageAnon(page))
+		return ret - compound * HPAGE_PMD_NR;
 	if (PageDoubleMap(page))
 		ret -= HPAGE_PMD_NR;
 	return ret;
diff --git a/mm/memory.c b/mm/memory.c
index 113ac4884c4e..ea9e4871e4e3 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1494,7 +1494,7 @@ static int insert_page(struct vm_area_struct *vma, unsigned long addr,
 	/* Ok, finally just insert the thing.. */
 	get_page(page);
 	inc_mm_counter_fast(mm, mm_counter_file(page));
-	page_add_file_rmap(page);
+	page_add_file_rmap(page, false);
 	set_pte_at(mm, addr, pte, mk_pte(page, prot));
 
 	retval = 0;
@@ -2965,7 +2965,7 @@ int alloc_set_pte(struct fault_env *fe, struct mem_cgroup *memcg,
 		lru_cache_add_active_or_unevictable(page, vma);
 	} else {
 		inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
-		page_add_file_rmap(page);
+		page_add_file_rmap(page, false);
 	}
 	set_pte_at(vma->vm_mm, fe->address, fe->pte, entry);
 
diff --git a/mm/migrate.c b/mm/migrate.c
index e6daf49e224f..7e6e9375d654 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -259,7 +259,7 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
 	} else if (PageAnon(new))
 		page_add_anon_rmap(new, vma, addr, false);
 	else
-		page_add_file_rmap(new);
+		page_add_file_rmap(new, false);
 
 	if (vma->vm_flags & VM_LOCKED && !PageTransCompound(new))
 		mlock_vma_page(new);
diff --git a/mm/rmap.c b/mm/rmap.c
index 0ea5d9071b32..b78374519bac 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1273,18 +1273,34 @@ void page_add_new_anon_rmap(struct page *page,
  *
  * The caller needs to hold the pte lock.
  */
-void page_add_file_rmap(struct page *page)
+void page_add_file_rmap(struct page *page, bool compound)
 {
+	int i, nr = 1;
+
+	VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
 	lock_page_memcg(page);
-	if (atomic_inc_and_test(&page->_mapcount)) {
-		__inc_zone_page_state(page, NR_FILE_MAPPED);
-		mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
+	if (compound && PageTransHuge(page)) {
+		for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
+			if (atomic_inc_and_test(&page[i]._mapcount))
+				nr++;
+		}
+		if (!atomic_inc_and_test(compound_mapcount_ptr(page)))
+			goto out;
+	} else {
+		if (!atomic_inc_and_test(&page->_mapcount))
+			goto out;
 	}
+	__mod_zone_page_state(page_zone(page), NR_FILE_MAPPED, nr);
+	mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
+out:
 	unlock_page_memcg(page);
 }
 
-static void page_remove_file_rmap(struct page *page)
+static void page_remove_file_rmap(struct page *page, bool compound)
 {
+	int i, nr = 1;
+
+	VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
 	lock_page_memcg(page);
 
 	/* Hugepages are not counted in NR_FILE_MAPPED for now. */
@@ -1295,15 +1311,24 @@ static void page_remove_file_rmap(struct page *page)
 	}
 
 	/* page still mapped by someone else? */
-	if (!atomic_add_negative(-1, &page->_mapcount))
-		goto out;
+	if (compound && PageTransHuge(page)) {
+		for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
+			if (atomic_add_negative(-1, &page[i]._mapcount))
+				nr++;
+		}
+		if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
+			goto out;
+	} else {
+		if (!atomic_add_negative(-1, &page->_mapcount))
+			goto out;
+	}
 
 	/*
 	 * We use the irq-unsafe __{inc|mod}_zone_page_stat because
 	 * these counters are not modified in interrupt context, and
 	 * pte lock(a spinlock) is held, which implies preemption disabled.
 	 */
-	__dec_zone_page_state(page, NR_FILE_MAPPED);
+	__mod_zone_page_state(page_zone(page), NR_FILE_MAPPED, -nr);
 	mem_cgroup_dec_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
 
 	if (unlikely(PageMlocked(page)))
@@ -1359,11 +1384,8 @@ static void page_remove_anon_compound_rmap(struct page *page)
  */
 void page_remove_rmap(struct page *page, bool compound)
 {
-	if (!PageAnon(page)) {
-		VM_BUG_ON_PAGE(compound && !PageHuge(page), page);
-		page_remove_file_rmap(page);
-		return;
-	}
+	if (!PageAnon(page))
+		return page_remove_file_rmap(page, compound);
 
 	if (compound)
 		return page_remove_anon_compound_rmap(page);
diff --git a/mm/util.c b/mm/util.c
index b756ee36f7f0..8d010ef2ce1c 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -412,6 +412,12 @@ int __page_mapcount(struct page *page)
 	int ret;
 
 	ret = atomic_read(&page->_mapcount) + 1;
+	/*
+	 * For file THP page->_mapcount contains total number of mapping
+	 * of the page: no need to look into compound_mapcount.
+	 */
+	if (!PageAnon(page) && !PageHuge(page))
+		return ret;
 	page = compound_head(page);
 	ret += atomic_read(compound_mapcount_ptr(page)) + 1;
 	if (PageDoubleMap(page))
-- 
2.8.1

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#1416032 — [PATCHv9-rebased 11/32] thp: skip file huge pmd on copy_huge_pmd()

copy_page_range() has a check for "Don't copy ptes where a page fault
will fill them correctly." It works on VMA level. We still copy all page
table entries from private mappings, even if they map page cache.

We can simplify copy_huge_pmd() a bit by skipping file PMDs.

We don't map file private pages with PMDs, so they only can map page
cache. It's safe to skip them as they can be re-faulted later.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 mm/huge_memory.c | 34 ++++++++++++++++------------------
 1 file changed, 16 insertions(+), 18 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index c9473faea7aa..b4dc62923dd7 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1099,14 +1099,15 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 	struct page *src_page;
 	pmd_t pmd;
 	pgtable_t pgtable = NULL;
-	int ret;
+	int ret = -ENOMEM;
 
-	if (!vma_is_dax(vma)) {
-		ret = -ENOMEM;
-		pgtable = pte_alloc_one(dst_mm, addr);
-		if (unlikely(!pgtable))
-			goto out;
-	}
+	/* Skip if can be re-fill on fault */
+	if (!vma_is_anonymous(vma))
+		return 0;
+
+	pgtable = pte_alloc_one(dst_mm, addr);
+	if (unlikely(!pgtable))
+		goto out;
 
 	dst_ptl = pmd_lock(dst_mm, dst_pmd);
 	src_ptl = pmd_lockptr(src_mm, src_pmd);
@@ -1114,7 +1115,7 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 
 	ret = -EAGAIN;
 	pmd = *src_pmd;
-	if (unlikely(!pmd_trans_huge(pmd) && !pmd_devmap(pmd))) {
+	if (unlikely(!pmd_trans_huge(pmd))) {
 		pte_free(dst_mm, pgtable);
 		goto out_unlock;
 	}
@@ -1137,16 +1138,13 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 		goto out_unlock;
 	}
 
-	if (!vma_is_dax(vma)) {
-		/* thp accounting separate from pmd_devmap accounting */
-		src_page = pmd_page(pmd);
-		VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
-		get_page(src_page);
-		page_dup_rmap(src_page, true);
-		add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
-		atomic_long_inc(&dst_mm->nr_ptes);
-		pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
-	}
+	src_page = pmd_page(pmd);
+	VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
+	get_page(src_page);
+	page_dup_rmap(src_page, true);
+	add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+	atomic_long_inc(&dst_mm->nr_ptes);
+	pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
 
 	pmdp_set_wrprotect(src_mm, addr, src_pmd);
 	pmd = pmd_mkold(pmd_wrprotect(pmd));
-- 
2.8.1

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#1416033 — [PATCHv9-rebased 00/32] THP-enabled tmpfs/shmem using compound pages

It's the same as v9, but rebased to v4.7-rc2-mmotm-2016-06-06-16-15 to
solve khugepaged-related conflicts.

It also can be found at

git://git.kernel.org/pub/scm/linux/kernel/git/kas/linux.git hugetmpfs/v9-rebased

Hugh Dickins (1):
  shmem: get_unmapped_area align huge page

Kirill A. Shutemov (31):
  thp, mlock: update unevictable-lru.txt
  mm: do not pass mm_struct into handle_mm_fault
  mm: introduce fault_env
  mm: postpone page table allocation until we have page to map
  rmap: support file thp
  mm: introduce do_set_pmd()
  thp, vmstats: add counters for huge file pages
  thp: support file pages in zap_huge_pmd()
  thp: handle file pages in split_huge_pmd()
  thp: handle file COW faults
  thp: skip file huge pmd on copy_huge_pmd()
  thp: prepare change_huge_pmd() for file thp
  thp: run vma_adjust_trans_huge() outside i_mmap_rwsem
  thp: file pages support for split_huge_page()
  thp, mlock: do not mlock PTE-mapped file huge pages
  vmscan: split file huge pages before paging them out
  page-flags: relax policy for PG_mappedtodisk and PG_reclaim
  radix-tree: implement radix_tree_maybe_preload_order()
  filemap: prepare find and delete operations for huge pages
  truncate: handle file thp
  mm, rmap: account shmem thp pages
  shmem: prepare huge= mount option and sysfs knob
  shmem: add huge pages support
  shmem, thp: respect MADV_{NO,}HUGEPAGE for file mappings
  thp: extract khugepaged from mm/huge_memory.c
  khugepaged: move up_read(mmap_sem) out of khugepaged_alloc_page()
  shmem: make shmem_inode_info::lock irq-safe
  khugepaged: add support of collapse for tmpfs/shmem pages
  thp: introduce CONFIG_TRANSPARENT_HUGE_PAGECACHE
  shmem: split huge pages beyond i_size under memory pressure
  thp: update Documentation/{vm/transhuge,filesystems/proc}.txt

 Documentation/filesystems/Locking    |   10 +-
 Documentation/filesystems/proc.txt   |    9 +
 Documentation/vm/transhuge.txt       |  128 ++-
 Documentation/vm/unevictable-lru.txt |   21 +
 arch/alpha/mm/fault.c                |    2 +-
 arch/arc/mm/fault.c                  |    2 +-
 arch/arm/mm/fault.c                  |    2 +-
 arch/arm64/mm/fault.c                |    2 +-
 arch/avr32/mm/fault.c                |    2 +-
 arch/cris/mm/fault.c                 |    2 +-
 arch/frv/mm/fault.c                  |    2 +-
 arch/hexagon/mm/vm_fault.c           |    2 +-
 arch/ia64/mm/fault.c                 |    2 +-
 arch/m32r/mm/fault.c                 |    2 +-
 arch/m68k/mm/fault.c                 |    2 +-
 arch/metag/mm/fault.c                |    2 +-
 arch/microblaze/mm/fault.c           |    2 +-
 arch/mips/mm/fault.c                 |    2 +-
 arch/mn10300/mm/fault.c              |    2 +-
 arch/nios2/mm/fault.c                |    2 +-
 arch/openrisc/mm/fault.c             |    2 +-
 arch/parisc/mm/fault.c               |    2 +-
 arch/powerpc/mm/copro_fault.c        |    2 +-
 arch/powerpc/mm/fault.c              |    2 +-
 arch/s390/mm/fault.c                 |    2 +-
 arch/score/mm/fault.c                |    2 +-
 arch/sh/mm/fault.c                   |    2 +-
 arch/sparc/mm/fault_32.c             |    4 +-
 arch/sparc/mm/fault_64.c             |    2 +-
 arch/tile/mm/fault.c                 |    2 +-
 arch/um/kernel/trap.c                |    2 +-
 arch/unicore32/mm/fault.c            |    2 +-
 arch/x86/mm/fault.c                  |    2 +-
 arch/xtensa/mm/fault.c               |    2 +-
 drivers/base/node.c                  |   13 +-
 drivers/char/mem.c                   |   24 +
 drivers/iommu/amd_iommu_v2.c         |    3 +-
 drivers/iommu/intel-svm.c            |    2 +-
 fs/proc/meminfo.c                    |    7 +-
 fs/proc/task_mmu.c                   |   10 +-
 fs/userfaultfd.c                     |   22 +-
 include/linux/huge_mm.h              |   36 +-
 include/linux/khugepaged.h           |    6 +
 include/linux/mm.h                   |   51 +-
 include/linux/mmzone.h               |    4 +-
 include/linux/page-flags.h           |   19 +-
 include/linux/radix-tree.h           |    1 +
 include/linux/rmap.h                 |    2 +-
 include/linux/shmem_fs.h             |   45 +-
 include/linux/userfaultfd_k.h        |    8 +-
 include/linux/vm_event_item.h        |    7 +
 include/trace/events/huge_memory.h   |    3 +-
 ipc/shm.c                            |   10 +-
 lib/radix-tree.c                     |   84 +-
 mm/Kconfig                           |    8 +
 mm/Makefile                          |    2 +-
 mm/filemap.c                         |  217 ++--
 mm/gup.c                             |    7 +-
 mm/huge_memory.c                     | 2101 ++++++----------------------------
 mm/internal.h                        |    4 +-
 mm/khugepaged.c                      | 1910 +++++++++++++++++++++++++++++++
 mm/ksm.c                             |    5 +-
 mm/memory.c                          |  879 +++++++-------
 mm/mempolicy.c                       |    2 +-
 mm/migrate.c                         |    5 +-
 mm/mmap.c                            |   26 +-
 mm/nommu.c                           |    3 +-
 mm/page-writeback.c                  |    1 +
 mm/page_alloc.c                      |   21 +
 mm/rmap.c                            |   78 +-
 mm/shmem.c                           |  918 +++++++++++++--
 mm/swap.c                            |    2 +
 mm/truncate.c                        |   28 +-
 mm/util.c                            |    6 +
 mm/vmscan.c                          |    6 +
 mm/vmstat.c                          |    4 +
 76 files changed, 4330 insertions(+), 2490 deletions(-)
 create mode 100644 mm/khugepaged.c

-- 
2.8.1

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#1416034 — [PATCHv9-rebased 22/32] shmem: prepare huge= mount option and sysfs knob

This patch adds new mount option "huge=". It can have following values:

  - "always":
	Attempt to allocate huge pages every time we need a new page;

  - "never":
	Do not allocate huge pages;

  - "within_size":
	Only allocate huge page if it will be fully within i_size.
	Also respect fadvise()/madvise() hints;

  - "advise:
	Only allocate huge pages if requested with fadvise()/madvise();

Default is "never" for now.

"mount -o remount,huge= /mountpoint" works fine after mount: remounting
huge=never will not attempt to break up huge pages at all, just stop
more from being allocated.

No new config option: put this under CONFIG_TRANSPARENT_HUGEPAGE,
which is the appropriate option to protect those who don't want
the new bloat, and with which we shall share some pmd code.

Prohibit the option when !CONFIG_TRANSPARENT_HUGEPAGE, just as mpol is
invalid without CONFIG_NUMA (was hidden in mpol_parse_str(): make it
explicit).

Allow enabling THP only if the machine has_transparent_hugepage().

But what about Shmem with no user-visible mount?  SysV SHM, memfds,
shared anonymous mmaps (of /dev/zero or MAP_ANONYMOUS), GPU drivers'
DRM objects, Ashmem.  Though unlikely to suit all usages, provide
sysfs knob /sys/kernel/mm/transparent_hugepage/shmem_enabled to
experiment with huge on those.

And allow shmem_enabled two further values:

  - "deny":
	For use in emergencies, to force the huge option off from
	all mounts;
  - "force":
	Force the huge option on for all - very useful for testing;

Based on patch by Hugh Dickins.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 include/linux/huge_mm.h  |   2 +
 include/linux/shmem_fs.h |   3 +-
 mm/huge_memory.c         |   3 +
 mm/shmem.c               | 161 +++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 168 insertions(+), 1 deletion(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 3ef07cd7730c..64dcd4e3fd72 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -41,6 +41,8 @@ enum transparent_hugepage_flag {
 #endif
 };
 
+extern struct kobj_attribute shmem_enabled_attr;
+
 #define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
 #define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER)
 
diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index 4d4780c00d34..466f18c73a49 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -28,9 +28,10 @@ struct shmem_sb_info {
 	unsigned long max_inodes;   /* How many inodes are allowed */
 	unsigned long free_inodes;  /* How many are left for allocation */
 	spinlock_t stat_lock;	    /* Serialize shmem_sb_info changes */
+	umode_t mode;		    /* Mount mode for root directory */
+	unsigned char huge;	    /* Whether to try for hugepages */
 	kuid_t uid;		    /* Mount uid for root directory */
 	kgid_t gid;		    /* Mount gid for root directory */
-	umode_t mode;		    /* Mount mode for root directory */
 	struct mempolicy *mpol;     /* default memory policy for mappings */
 };
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index ada33b395f24..a67d7188a5af 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -443,6 +443,9 @@ static struct attribute *hugepage_attr[] = {
 	&enabled_attr.attr,
 	&defrag_attr.attr,
 	&use_zero_page_attr.attr,
+#ifdef CONFIG_SHMEM
+	&shmem_enabled_attr.attr,
+#endif
 #ifdef CONFIG_DEBUG_VM
 	&debug_cow_attr.attr,
 #endif
diff --git a/mm/shmem.c b/mm/shmem.c
index a36144909b28..dfbc9266b097 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -289,6 +289,87 @@ static bool shmem_confirm_swap(struct address_space *mapping,
 }
 
 /*
+ * Definitions for "huge tmpfs": tmpfs mounted with the huge= option
+ *
+ * SHMEM_HUGE_NEVER:
+ *	disables huge pages for the mount;
+ * SHMEM_HUGE_ALWAYS:
+ *	enables huge pages for the mount;
+ * SHMEM_HUGE_WITHIN_SIZE:
+ *	only allocate huge pages if the page will be fully within i_size,
+ *	also respect fadvise()/madvise() hints;
+ * SHMEM_HUGE_ADVISE:
+ *	only allocate huge pages if requested with fadvise()/madvise();
+ */
+
+#define SHMEM_HUGE_NEVER	0
+#define SHMEM_HUGE_ALWAYS	1
+#define SHMEM_HUGE_WITHIN_SIZE	2
+#define SHMEM_HUGE_ADVISE	3
+
+/*
+ * Special values.
+ * Only can be set via /sys/kernel/mm/transparent_hugepage/shmem_enabled:
+ *
+ * SHMEM_HUGE_DENY:
+ *	disables huge on shm_mnt and all mounts, for emergency use;
+ * SHMEM_HUGE_FORCE:
+ *	enables huge on shm_mnt and all mounts, w/o needing option, for testing;
+ *
+ */
+#define SHMEM_HUGE_DENY		(-1)
+#define SHMEM_HUGE_FORCE	(-2)
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+/* ifdef here to avoid bloating shmem.o when not necessary */
+
+int shmem_huge __read_mostly;
+
+static int shmem_parse_huge(const char *str)
+{
+	if (!strcmp(str, "never"))
+		return SHMEM_HUGE_NEVER;
+	if (!strcmp(str, "always"))
+		return SHMEM_HUGE_ALWAYS;
+	if (!strcmp(str, "within_size"))
+		return SHMEM_HUGE_WITHIN_SIZE;
+	if (!strcmp(str, "advise"))
+		return SHMEM_HUGE_ADVISE;
+	if (!strcmp(str, "deny"))
+		return SHMEM_HUGE_DENY;
+	if (!strcmp(str, "force"))
+		return SHMEM_HUGE_FORCE;
+	return -EINVAL;
+}
+
+static const char *shmem_format_huge(int huge)
+{
+	switch (huge) {
+	case SHMEM_HUGE_NEVER:
+		return "never";
+	case SHMEM_HUGE_ALWAYS:
+		return "always";
+	case SHMEM_HUGE_WITHIN_SIZE:
+		return "within_size";
+	case SHMEM_HUGE_ADVISE:
+		return "advise";
+	case SHMEM_HUGE_DENY:
+		return "deny";
+	case SHMEM_HUGE_FORCE:
+		return "force";
+	default:
+		VM_BUG_ON(1);
+		return "bad_val";
+	}
+}
+
+#else /* !CONFIG_TRANSPARENT_HUGEPAGE */
+
+#define shmem_huge SHMEM_HUGE_DENY
+
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
+/*
  * Like add_to_page_cache_locked, but error if expected item has gone.
  */
 static int shmem_add_to_page_cache(struct page *page,
@@ -2858,11 +2939,24 @@ static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
 			sbinfo->gid = make_kgid(current_user_ns(), gid);
 			if (!gid_valid(sbinfo->gid))
 				goto bad_val;
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+		} else if (!strcmp(this_char, "huge")) {
+			int huge;
+			huge = shmem_parse_huge(value);
+			if (huge < 0)
+				goto bad_val;
+			if (!has_transparent_hugepage() &&
+					huge != SHMEM_HUGE_NEVER)
+				goto bad_val;
+			sbinfo->huge = huge;
+#endif
+#ifdef CONFIG_NUMA
 		} else if (!strcmp(this_char,"mpol")) {
 			mpol_put(mpol);
 			mpol = NULL;
 			if (mpol_parse_str(value, &mpol))
 				goto bad_val;
+#endif
 		} else {
 			pr_err("tmpfs: Bad mount option %s\n", this_char);
 			goto error;
@@ -2908,6 +3002,7 @@ static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
 		goto out;
 
 	error = 0;
+	sbinfo->huge = config.huge;
 	sbinfo->max_blocks  = config.max_blocks;
 	sbinfo->max_inodes  = config.max_inodes;
 	sbinfo->free_inodes = config.max_inodes - inodes;
@@ -2941,6 +3036,11 @@ static int shmem_show_options(struct seq_file *seq, struct dentry *root)
 	if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
 		seq_printf(seq, ",gid=%u",
 				from_kgid_munged(&init_user_ns, sbinfo->gid));
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	/* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
+	if (sbinfo->huge)
+		seq_printf(seq, ",huge=%s", shmem_format_huge(sbinfo->huge));
+#endif
 	shmem_show_mpol(seq, sbinfo->mpol);
 	return 0;
 }
@@ -3280,6 +3380,13 @@ int __init shmem_init(void)
 		pr_err("Could not kern_mount tmpfs\n");
 		goto out1;
 	}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	if (has_transparent_hugepage() && shmem_huge < SHMEM_HUGE_DENY)
+		SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
+	else
+		shmem_huge = 0; /* just in case it was patched */
+#endif
 	return 0;
 
 out1:
@@ -3291,6 +3398,60 @@ out3:
 	return error;
 }
 
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && defined(CONFIG_SYSFS)
+static ssize_t shmem_enabled_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	int values[] = {
+		SHMEM_HUGE_ALWAYS,
+		SHMEM_HUGE_WITHIN_SIZE,
+		SHMEM_HUGE_ADVISE,
+		SHMEM_HUGE_NEVER,
+		SHMEM_HUGE_DENY,
+		SHMEM_HUGE_FORCE,
+	};
+	int i, count;
+
+	for (i = 0, count = 0; i < ARRAY_SIZE(values); i++) {
+		const char *fmt = shmem_huge == values[i] ? "[%s] " : "%s ";
+
+		count += sprintf(buf + count, fmt,
+				shmem_format_huge(values[i]));
+	}
+	buf[count - 1] = '\n';
+	return count;
+}
+
+static ssize_t shmem_enabled_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	char tmp[16];
+	int huge;
+
+	if (count + 1 > sizeof(tmp))
+		return -EINVAL;
+	memcpy(tmp, buf, count);
+	tmp[count] = '\0';
+	if (count && tmp[count - 1] == '\n')
+		tmp[count - 1] = '\0';
+
+	huge = shmem_parse_huge(tmp);
+	if (huge == -EINVAL)
+		return -EINVAL;
+	if (!has_transparent_hugepage() &&
+			huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
+		return -EINVAL;
+
+	shmem_huge = huge;
+	if (shmem_huge < SHMEM_HUGE_DENY)
+		SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
+	return count;
+}
+
+struct kobj_attribute shmem_enabled_attr =
+	__ATTR(shmem_enabled, 0644, shmem_enabled_show, shmem_enabled_store);
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
+
 #else /* !CONFIG_SHMEM */
 
 /*
-- 
2.8.1

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#1416035 — [PATCHv9-rebased 15/32] thp, mlock: do not mlock PTE-mapped file huge pages

As with anon THP, we only mlock file huge pages if we can prove that the
page is not mapped with PTE. This way we can avoid mlock leak into
non-mlocked vma on split.

We rely on PageDoubleMap() under lock_page() to check if the the page
may be PTE mapped. PG_double_map is set by page_add_file_rmap() when the
page mapped with PTEs.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 include/linux/page-flags.h | 13 ++++++++++++-
 mm/huge_memory.c           | 27 ++++++++++++++++++++-------
 mm/mmap.c                  |  6 ++++++
 mm/page_alloc.c            |  2 ++
 mm/rmap.c                  | 16 ++++++++++++++--
 5 files changed, 54 insertions(+), 10 deletions(-)

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 7c8e82ac2eb7..8cf09639185a 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -581,6 +581,17 @@ static inline int PageDoubleMap(struct page *page)
 	return PageHead(page) && test_bit(PG_double_map, &page[1].flags);
 }
 
+static inline void SetPageDoubleMap(struct page *page)
+{
+	VM_BUG_ON_PAGE(!PageHead(page), page);
+	set_bit(PG_double_map, &page[1].flags);
+}
+
+static inline void ClearPageDoubleMap(struct page *page)
+{
+	VM_BUG_ON_PAGE(!PageHead(page), page);
+	clear_bit(PG_double_map, &page[1].flags);
+}
 static inline int TestSetPageDoubleMap(struct page *page)
 {
 	VM_BUG_ON_PAGE(!PageHead(page), page);
@@ -598,7 +609,7 @@ TESTPAGEFLAG_FALSE(TransHuge)
 TESTPAGEFLAG_FALSE(TransCompound)
 TESTPAGEFLAG_FALSE(TransCompoundMap)
 TESTPAGEFLAG_FALSE(TransTail)
-TESTPAGEFLAG_FALSE(DoubleMap)
+PAGEFLAG_FALSE(DoubleMap)
 	TESTSETFLAG_FALSE(DoubleMap)
 	TESTCLEARFLAG_FALSE(DoubleMap)
 #endif
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b3b2bf3da167..28e7d963cc1f 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1438,6 +1438,8 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
 		 * We don't mlock() pte-mapped THPs. This way we can avoid
 		 * leaking mlocked pages into non-VM_LOCKED VMAs.
 		 *
+		 * For anon THP:
+		 *
 		 * In most cases the pmd is the only mapping of the page as we
 		 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
 		 * writable private mappings in populate_vma_page_range().
@@ -1445,15 +1447,26 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
 		 * The only scenario when we have the page shared here is if we
 		 * mlocking read-only mapping shared over fork(). We skip
 		 * mlocking such pages.
+		 *
+		 * For file THP:
+		 *
+		 * We can expect PageDoubleMap() to be stable under page lock:
+		 * for file pages we set it in page_add_file_rmap(), which
+		 * requires page to be locked.
 		 */
-		if (compound_mapcount(page) == 1 && !PageDoubleMap(page) &&
-				page->mapping && trylock_page(page)) {
-			lru_add_drain();
-			if (page->mapping)
-				mlock_vma_page(page);
-			unlock_page(page);
-		}
+
+		if (PageAnon(page) && compound_mapcount(page) != 1)
+			goto skip_mlock;
+		if (PageDoubleMap(page) || !page->mapping)
+			goto skip_mlock;
+		if (!trylock_page(page))
+			goto skip_mlock;
+		lru_add_drain();
+		if (page->mapping && !PageDoubleMap(page))
+			mlock_vma_page(page);
+		unlock_page(page);
 	}
+skip_mlock:
 	page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
 	VM_BUG_ON_PAGE(!PageCompound(page), page);
 	if (flags & FOLL_GET)
diff --git a/mm/mmap.c b/mm/mmap.c
index 02990e7dd70e..daabef097c78 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2591,6 +2591,12 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
 		/* drop PG_Mlocked flag for over-mapped range */
 		for (tmp = vma; tmp->vm_start >= start + size;
 				tmp = tmp->vm_next) {
+			/*
+			 * Split pmd and munlock page on the border
+			 * of the range.
+			 */
+			vma_adjust_trans_huge(tmp, start, start + size, 0);
+
 			munlock_vma_pages_range(tmp,
 					max(tmp->vm_start, start),
 					min(tmp->vm_end, start + size));
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a46547389e53..e32ff3abe9da 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1005,6 +1005,8 @@ static __always_inline bool free_pages_prepare(struct page *page,
 
 		VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
 
+		if (compound)
+			ClearPageDoubleMap(page);
 		for (i = 1; i < (1 << order); i++) {
 			if (compound)
 				bad += free_tail_pages_check(page, page + i);
diff --git a/mm/rmap.c b/mm/rmap.c
index b78374519bac..26e3e784ad75 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1287,6 +1287,12 @@ void page_add_file_rmap(struct page *page, bool compound)
 		if (!atomic_inc_and_test(compound_mapcount_ptr(page)))
 			goto out;
 	} else {
+		if (PageTransCompound(page)) {
+			VM_BUG_ON_PAGE(!PageLocked(page), page);
+			SetPageDoubleMap(compound_head(page));
+			if (PageMlocked(page))
+				clear_page_mlock(compound_head(page));
+		}
 		if (!atomic_inc_and_test(&page->_mapcount))
 			goto out;
 	}
@@ -1460,8 +1466,14 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 	 */
 	if (!(flags & TTU_IGNORE_MLOCK)) {
 		if (vma->vm_flags & VM_LOCKED) {
-			/* Holding pte lock, we do *not* need mmap_sem here */
-			mlock_vma_page(page);
+			/* PTE-mapped THP are never mlocked */
+			if (!PageTransCompound(page)) {
+				/*
+				 * Holding pte lock, we do *not* need
+				 * mmap_sem here
+				 */
+				mlock_vma_page(page);
+			}
 			ret = SWAP_MLOCK;
 			goto out_unmap;
 		}
-- 
2.8.1

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#1416036 — [PATCHv9-rebased 17/32] page-flags: relax policy for PG_mappedtodisk and PG_reclaim

These flags are in use for file THP.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 include/linux/page-flags.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 8cf09639185a..74e4dda91238 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -295,11 +295,11 @@ PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
  */
 TESTPAGEFLAG(Writeback, writeback, PF_NO_COMPOUND)
 	TESTSCFLAG(Writeback, writeback, PF_NO_COMPOUND)
-PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_COMPOUND)
+PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
 
 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
-PAGEFLAG(Reclaim, reclaim, PF_NO_COMPOUND)
-	TESTCLEARFLAG(Reclaim, reclaim, PF_NO_COMPOUND)
+PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
+	TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
 PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
 	TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)
 
-- 
2.8.1

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#1416037 — [PATCHv9-rebased 20/32] truncate: handle file thp

For shmem/tmpfs we only need to tweak truncate_inode_page() and
invalidate_mapping_pages().

truncate_inode_pages_range() and invalidate_inode_pages2_range() are
adjusted to use page_to_pgoff().

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 mm/truncate.c | 28 +++++++++++++++++++++++-----
 1 file changed, 23 insertions(+), 5 deletions(-)

diff --git a/mm/truncate.c b/mm/truncate.c
index 4064f8f53daa..a01cce450a26 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -155,10 +155,14 @@ invalidate_complete_page(struct address_space *mapping, struct page *page)
 
 int truncate_inode_page(struct address_space *mapping, struct page *page)
 {
+	loff_t holelen;
+	VM_BUG_ON_PAGE(PageTail(page), page);
+
+	holelen = PageTransHuge(page) ? HPAGE_PMD_SIZE : PAGE_SIZE;
 	if (page_mapped(page)) {
 		unmap_mapping_range(mapping,
 				   (loff_t)page->index << PAGE_SHIFT,
-				   PAGE_SIZE, 0);
+				   holelen, 0);
 	}
 	return truncate_complete_page(mapping, page);
 }
@@ -279,7 +283,7 @@ void truncate_inode_pages_range(struct address_space *mapping,
 
 			if (!trylock_page(page))
 				continue;
-			WARN_ON(page->index != index);
+			WARN_ON(page_to_pgoff(page) != index);
 			if (PageWriteback(page)) {
 				unlock_page(page);
 				continue;
@@ -367,7 +371,7 @@ void truncate_inode_pages_range(struct address_space *mapping,
 			}
 
 			lock_page(page);
-			WARN_ON(page->index != index);
+			WARN_ON(page_to_pgoff(page) != index);
 			wait_on_page_writeback(page);
 			truncate_inode_page(mapping, page);
 			unlock_page(page);
@@ -487,7 +491,21 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping,
 
 			if (!trylock_page(page))
 				continue;
-			WARN_ON(page->index != index);
+
+			WARN_ON(page_to_pgoff(page) != index);
+
+			/* Middle of THP: skip */
+			if (PageTransTail(page)) {
+				unlock_page(page);
+				continue;
+			} else if (PageTransHuge(page)) {
+				index += HPAGE_PMD_NR - 1;
+				i += HPAGE_PMD_NR - 1;
+				/* 'end' is in the middle of THP */
+				if (index ==  round_down(end, HPAGE_PMD_NR))
+					continue;
+			}
+
 			ret = invalidate_inode_page(page);
 			unlock_page(page);
 			/*
@@ -594,7 +612,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
 			}
 
 			lock_page(page);
-			WARN_ON(page->index != index);
+			WARN_ON(page_to_pgoff(page) != index);
 			if (page->mapping != mapping) {
 				unlock_page(page);
 				continue;
-- 
2.8.1

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#1416038 — [PATCHv9-rebased 18/32] radix-tree: implement radix_tree_maybe_preload_order()

The new helper is similar to radix_tree_maybe_preload(), but tries to
preload number of nodes required to insert (1 << order) continuous
naturally-aligned elements.

This is required to push huge pages into pagecache.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 include/linux/radix-tree.h |  1 +
 lib/radix-tree.c           | 84 +++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 80 insertions(+), 5 deletions(-)

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index cb4b7e8cee81..084965cf90fc 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -291,6 +291,7 @@ unsigned int radix_tree_gang_lookup_slot(struct radix_tree_root *root,
 			unsigned long first_index, unsigned int max_items);
 int radix_tree_preload(gfp_t gfp_mask);
 int radix_tree_maybe_preload(gfp_t gfp_mask);
+int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order);
 void radix_tree_init(void);
 void *radix_tree_tag_set(struct radix_tree_root *root,
 			unsigned long index, unsigned int tag);
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 8b7d8459bb9d..61b8fb529cef 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -38,6 +38,9 @@
 #include <linux/preempt.h>		/* in_interrupt() */
 
 
+/* Number of nodes in fully populated tree of given height */
+static unsigned long height_to_maxnodes[RADIX_TREE_MAX_PATH + 1] __read_mostly;
+
 /*
  * Radix tree node cache.
  */
@@ -342,7 +345,7 @@ radix_tree_node_free(struct radix_tree_node *node)
  * To make use of this facility, the radix tree must be initialised without
  * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
  */
-static int __radix_tree_preload(gfp_t gfp_mask)
+static int __radix_tree_preload(gfp_t gfp_mask, int nr)
 {
 	struct radix_tree_preload *rtp;
 	struct radix_tree_node *node;
@@ -350,14 +353,14 @@ static int __radix_tree_preload(gfp_t gfp_mask)
 
 	preempt_disable();
 	rtp = this_cpu_ptr(&radix_tree_preloads);
-	while (rtp->nr < RADIX_TREE_PRELOAD_SIZE) {
+	while (rtp->nr < nr) {
 		preempt_enable();
 		node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
 		if (node == NULL)
 			goto out;
 		preempt_disable();
 		rtp = this_cpu_ptr(&radix_tree_preloads);
-		if (rtp->nr < RADIX_TREE_PRELOAD_SIZE) {
+		if (rtp->nr < nr) {
 			node->private_data = rtp->nodes;
 			rtp->nodes = node;
 			rtp->nr++;
@@ -383,7 +386,7 @@ int radix_tree_preload(gfp_t gfp_mask)
 {
 	/* Warn on non-sensical use... */
 	WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
-	return __radix_tree_preload(gfp_mask);
+	return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
 }
 EXPORT_SYMBOL(radix_tree_preload);
 
@@ -395,7 +398,7 @@ EXPORT_SYMBOL(radix_tree_preload);
 int radix_tree_maybe_preload(gfp_t gfp_mask)
 {
 	if (gfpflags_allow_blocking(gfp_mask))
-		return __radix_tree_preload(gfp_mask);
+		return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
 	/* Preloading doesn't help anything with this gfp mask, skip it */
 	preempt_disable();
 	return 0;
@@ -403,6 +406,51 @@ int radix_tree_maybe_preload(gfp_t gfp_mask)
 EXPORT_SYMBOL(radix_tree_maybe_preload);
 
 /*
+ * The same as function above, but preload number of nodes required to insert
+ * (1 << order) continuous naturally-aligned elements.
+ */
+int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order)
+{
+	unsigned long nr_subtrees;
+	int nr_nodes, subtree_height;
+
+	/* Preloading doesn't help anything with this gfp mask, skip it */
+	if (!gfpflags_allow_blocking(gfp_mask)) {
+		preempt_disable();
+		return 0;
+	}
+
+	/*
+	 * Calculate number and height of fully populated subtrees it takes to
+	 * store (1 << order) elements.
+	 */
+	nr_subtrees = 1 << order;
+	for (subtree_height = 0; nr_subtrees > RADIX_TREE_MAP_SIZE;
+			subtree_height++)
+		nr_subtrees >>= RADIX_TREE_MAP_SHIFT;
+
+	/*
+	 * The worst case is zero height tree with a single item at index 0 and
+	 * then inserting items starting at ULONG_MAX - (1 << order).
+	 *
+	 * This requires RADIX_TREE_MAX_PATH nodes to build branch from root to
+	 * 0-index item.
+	 */
+	nr_nodes = RADIX_TREE_MAX_PATH;
+
+	/* Plus branch to fully populated subtrees. */
+	nr_nodes += RADIX_TREE_MAX_PATH - subtree_height;
+
+	/* Root node is shared. */
+	nr_nodes--;
+
+	/* Plus nodes required to build subtrees. */
+	nr_nodes += nr_subtrees * height_to_maxnodes[subtree_height];
+
+	return __radix_tree_preload(gfp_mask, nr_nodes);
+}
+
+/*
  * The maximum index which can be stored in a radix tree
  */
 static inline unsigned long shift_maxindex(unsigned int shift)
@@ -1571,6 +1619,31 @@ radix_tree_node_ctor(void *arg)
 	INIT_LIST_HEAD(&node->private_list);
 }
 
+static __init unsigned long __maxindex(unsigned int height)
+{
+	unsigned int width = height * RADIX_TREE_MAP_SHIFT;
+	int shift = RADIX_TREE_INDEX_BITS - width;
+
+	if (shift < 0)
+		return ~0UL;
+	if (shift >= BITS_PER_LONG)
+		return 0UL;
+	return ~0UL >> shift;
+}
+
+static __init void radix_tree_init_maxnodes(void)
+{
+	unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1];
+	unsigned int i, j;
+
+	for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
+		height_to_maxindex[i] = __maxindex(i);
+	for (i = 0; i < ARRAY_SIZE(height_to_maxnodes); i++) {
+		for (j = i; j > 0; j--)
+			height_to_maxnodes[i] += height_to_maxindex[j - 1] + 1;
+	}
+}
+
 static int radix_tree_callback(struct notifier_block *nfb,
 				unsigned long action, void *hcpu)
 {
@@ -1597,5 +1670,6 @@ void __init radix_tree_init(void)
 			sizeof(struct radix_tree_node), 0,
 			SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
 			radix_tree_node_ctor);
+	radix_tree_init_maxnodes();
 	hotcpu_notifier(radix_tree_callback, 0);
 }
-- 
2.8.1

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#1416039 — [PATCHv9-rebased 09/32] thp: handle file pages in split_huge_pmd()

Splitting THP PMD is simple: just unmap it as in DAX case. This way we
can avoid memory overhead on page table allocation to deposit.

It's probably a good idea to try to allocation page table with
GFP_ATOMIC in __split_huge_pmd_locked() to avoid refaulting the area,
but clearing pmd should be good enough for now.

Unlike DAX, we also remove the page from rmap and drop reference.
pmd_young() is transfered to PageReferenced().

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 mm/huge_memory.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 1ffd53de82ce..c9473faea7aa 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2994,10 +2994,18 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 
 	count_vm_event(THP_SPLIT_PMD);
 
-	if (vma_is_dax(vma)) {
-		pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
+	if (!vma_is_anonymous(vma)) {
+		_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
 		if (is_huge_zero_pmd(_pmd))
 			put_huge_zero_page();
+		if (vma_is_dax(vma))
+			return;
+		page = pmd_page(_pmd);
+		if (!PageReferenced(page) && pmd_young(_pmd))
+			SetPageReferenced(page);
+		page_remove_rmap(page, true);
+		put_page(page);
+		add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR);
 		return;
 	} else if (is_huge_zero_pmd(*pmd)) {
 		return __split_huge_zero_page_pmd(vma, haddr, pmd);
-- 
2.8.1

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#1416040 — [PATCHv9-rebased 14/32] thp: file pages support for split_huge_page()

Basic scheme is the same as for anon THP.

Main differences:

  - File pages are on radix-tree, so we have head->_count offset by
    HPAGE_PMD_NR. The count got distributed to small pages during split.

  - mapping->tree_lock prevents non-lockless access to pages under split
    over radix-tree;

  - Lockless access is prevented by setting the head->_count to 0 during
    split;

  - After split, some pages can be beyond i_size. We drop them from
    radix-tree.

  - We don't setup migration entries. Just unmap pages. It helps
    handling cases when i_size is in the middle of the page: no need
    handle unmap pages beyond i_size manually.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 mm/gup.c         |   2 +
 mm/huge_memory.c | 160 +++++++++++++++++++++++++++++++++++++++----------------
 2 files changed, 117 insertions(+), 45 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 9671e29f8ffd..547741f5f7a7 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -288,6 +288,8 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
 			ret = split_huge_page(page);
 			unlock_page(page);
 			put_page(page);
+			if (pmd_none(*pmd))
+				return no_page_table(vma, flags);
 		}
 
 		return ret ? ERR_PTR(ret) :
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index c52119eb2998..b3b2bf3da167 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -30,6 +30,7 @@
 #include <linux/hashtable.h>
 #include <linux/userfaultfd_k.h>
 #include <linux/page_idle.h>
+#include <linux/shmem_fs.h>
 
 #include <asm/tlb.h>
 #include <asm/pgalloc.h>
@@ -3201,12 +3202,15 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma,
 
 static void freeze_page(struct page *page)
 {
-	enum ttu_flags ttu_flags = TTU_MIGRATION | TTU_IGNORE_MLOCK |
-		TTU_IGNORE_ACCESS | TTU_RMAP_LOCKED;
+	enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
+		TTU_RMAP_LOCKED;
 	int i, ret;
 
 	VM_BUG_ON_PAGE(!PageHead(page), page);
 
+	if (PageAnon(page))
+		ttu_flags |= TTU_MIGRATION;
+
 	/* We only need TTU_SPLIT_HUGE_PMD once */
 	ret = try_to_unmap(page, ttu_flags | TTU_SPLIT_HUGE_PMD);
 	for (i = 1; !ret && i < HPAGE_PMD_NR; i++) {
@@ -3216,7 +3220,7 @@ static void freeze_page(struct page *page)
 
 		ret = try_to_unmap(page + i, ttu_flags);
 	}
-	VM_BUG_ON(ret);
+	VM_BUG_ON_PAGE(ret, page + i - 1);
 }
 
 static void unfreeze_page(struct page *page)
@@ -3238,15 +3242,20 @@ static void __split_huge_page_tail(struct page *head, int tail,
 	/*
 	 * tail_page->_refcount is zero and not changing from under us. But
 	 * get_page_unless_zero() may be running from under us on the
-	 * tail_page. If we used atomic_set() below instead of atomic_inc(), we
-	 * would then run atomic_set() concurrently with
+	 * tail_page. If we used atomic_set() below instead of atomic_inc() or
+	 * atomic_add(), we would then run atomic_set() concurrently with
 	 * get_page_unless_zero(), and atomic_set() is implemented in C not
 	 * using locked ops. spin_unlock on x86 sometime uses locked ops
 	 * because of PPro errata 66, 92, so unless somebody can guarantee
 	 * atomic_set() here would be safe on all archs (and not only on x86),
-	 * it's safer to use atomic_inc().
+	 * it's safer to use atomic_inc()/atomic_add().
 	 */
-	page_ref_inc(page_tail);
+	if (PageAnon(head)) {
+		page_ref_inc(page_tail);
+	} else {
+		/* Additional pin to radix tree */
+		page_ref_add(page_tail, 2);
+	}
 
 	page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
 	page_tail->flags |= (head->flags &
@@ -3282,25 +3291,44 @@ static void __split_huge_page_tail(struct page *head, int tail,
 	lru_add_page_tail(head, page_tail, lruvec, list);
 }
 
-static void __split_huge_page(struct page *page, struct list_head *list)
+static void __split_huge_page(struct page *page, struct list_head *list,
+		unsigned long flags)
 {
 	struct page *head = compound_head(page);
 	struct zone *zone = page_zone(head);
 	struct lruvec *lruvec;
+	pgoff_t end = -1;
 	int i;
 
-	/* prevent PageLRU to go away from under us, and freeze lru stats */
-	spin_lock_irq(&zone->lru_lock);
 	lruvec = mem_cgroup_page_lruvec(head, zone);
 
 	/* complete memcg works before add pages to LRU */
 	mem_cgroup_split_huge_fixup(head);
 
-	for (i = HPAGE_PMD_NR - 1; i >= 1; i--)
+	if (!PageAnon(page))
+		end = DIV_ROUND_UP(i_size_read(head->mapping->host), PAGE_SIZE);
+
+	for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
 		__split_huge_page_tail(head, i, lruvec, list);
+		/* Some pages can be beyond i_size: drop them from page cache */
+		if (head[i].index >= end) {
+			__ClearPageDirty(head + i);
+			__delete_from_page_cache(head + i, NULL);
+			put_page(head + i);
+		}
+	}
 
 	ClearPageCompound(head);
-	spin_unlock_irq(&zone->lru_lock);
+	/* See comment in __split_huge_page_tail() */
+	if (PageAnon(head)) {
+		page_ref_inc(head);
+	} else {
+		/* Additional pin to radix tree */
+		page_ref_add(head, 2);
+		spin_unlock(&head->mapping->tree_lock);
+	}
+
+	spin_unlock_irqrestore(&page_zone(head)->lru_lock, flags);
 
 	unfreeze_page(head);
 
@@ -3425,36 +3453,54 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 {
 	struct page *head = compound_head(page);
 	struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
-	struct anon_vma *anon_vma;
-	int count, mapcount, ret;
+	struct anon_vma *anon_vma = NULL;
+	struct address_space *mapping = NULL;
+	int count, mapcount, extra_pins, ret;
 	bool mlocked;
 	unsigned long flags;
 
 	VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
-	VM_BUG_ON_PAGE(!PageAnon(page), page);
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
 	VM_BUG_ON_PAGE(!PageCompound(page), page);
 
-	/*
-	 * The caller does not necessarily hold an mmap_sem that would prevent
-	 * the anon_vma disappearing so we first we take a reference to it
-	 * and then lock the anon_vma for write. This is similar to
-	 * page_lock_anon_vma_read except the write lock is taken to serialise
-	 * against parallel split or collapse operations.
-	 */
-	anon_vma = page_get_anon_vma(head);
-	if (!anon_vma) {
-		ret = -EBUSY;
-		goto out;
+	if (PageAnon(head)) {
+		/*
+		 * The caller does not necessarily hold an mmap_sem that would
+		 * prevent the anon_vma disappearing so we first we take a
+		 * reference to it and then lock the anon_vma for write. This
+		 * is similar to page_lock_anon_vma_read except the write lock
+		 * is taken to serialise against parallel split or collapse
+		 * operations.
+		 */
+		anon_vma = page_get_anon_vma(head);
+		if (!anon_vma) {
+			ret = -EBUSY;
+			goto out;
+		}
+		extra_pins = 0;
+		mapping = NULL;
+		anon_vma_lock_write(anon_vma);
+	} else {
+		mapping = head->mapping;
+
+		/* Truncated ? */
+		if (!mapping) {
+			ret = -EBUSY;
+			goto out;
+		}
+
+		/* Addidional pins from radix tree */
+		extra_pins = HPAGE_PMD_NR;
+		anon_vma = NULL;
+		i_mmap_lock_read(mapping);
 	}
-	anon_vma_lock_write(anon_vma);
 
 	/*
 	 * Racy check if we can split the page, before freeze_page() will
 	 * split PMDs
 	 */
-	if (total_mapcount(head) != page_count(head) - 1) {
+	if (total_mapcount(head) != page_count(head) - extra_pins - 1) {
 		ret = -EBUSY;
 		goto out_unlock;
 	}
@@ -3467,35 +3513,60 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 	if (mlocked)
 		lru_add_drain();
 
+	/* prevent PageLRU to go away from under us, and freeze lru stats */
+	spin_lock_irqsave(&page_zone(head)->lru_lock, flags);
+
+	if (mapping) {
+		void **pslot;
+
+		spin_lock(&mapping->tree_lock);
+		pslot = radix_tree_lookup_slot(&mapping->page_tree,
+				page_index(head));
+		/*
+		 * Check if the head page is present in radix tree.
+		 * We assume all tail are present too, if head is there.
+		 */
+		if (radix_tree_deref_slot_protected(pslot,
+					&mapping->tree_lock) != head)
+			goto fail;
+	}
+
 	/* Prevent deferred_split_scan() touching ->_refcount */
-	spin_lock_irqsave(&pgdata->split_queue_lock, flags);
+	spin_lock(&pgdata->split_queue_lock);
 	count = page_count(head);
 	mapcount = total_mapcount(head);
-	if (!mapcount && count == 1) {
+	if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
 		if (!list_empty(page_deferred_list(head))) {
 			pgdata->split_queue_len--;
 			list_del(page_deferred_list(head));
 		}
-		spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
-		__split_huge_page(page, list);
+		spin_unlock(&pgdata->split_queue_lock);
+		__split_huge_page(page, list, flags);
 		ret = 0;
-	} else if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
-		spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
-		pr_alert("total_mapcount: %u, page_count(): %u\n",
-				mapcount, count);
-		if (PageTail(page))
-			dump_page(head, NULL);
-		dump_page(page, "total_mapcount(head) > 0");
-		BUG();
 	} else {
-		spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
+		if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
+			pr_alert("total_mapcount: %u, page_count(): %u\n",
+					mapcount, count);
+			if (PageTail(page))
+				dump_page(head, NULL);
+			dump_page(page, "total_mapcount(head) > 0");
+			BUG();
+		}
+		spin_unlock(&pgdata->split_queue_lock);
+fail:		if (mapping)
+			spin_unlock(&mapping->tree_lock);
+		spin_unlock_irqrestore(&page_zone(head)->lru_lock, flags);
 		unfreeze_page(head);
 		ret = -EBUSY;
 	}
 
 out_unlock:
-	anon_vma_unlock_write(anon_vma);
-	put_anon_vma(anon_vma);
+	if (anon_vma) {
+		anon_vma_unlock_write(anon_vma);
+		put_anon_vma(anon_vma);
+	}
+	if (mapping)
+		i_mmap_unlock_read(mapping);
 out:
 	count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
 	return ret;
@@ -3618,8 +3689,7 @@ static int split_huge_pages_set(void *data, u64 val)
 			if (zone != page_zone(page))
 				goto next;
 
-			if (!PageHead(page) || !PageAnon(page) ||
-					PageHuge(page))
+			if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
 				goto next;
 
 			total++;
-- 
2.8.1

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