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[PATCHv9-rebased2 00/37] THP-enabled tmpfs/shmem using compound pages

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  [PATCHv9-rebased2 00/37] THP-enabled tmpfs/shmem using compound pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 05/37] khugepaged: recheck pmd after mmap_sem re-acquired "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
      Re: [PATCHv9-rebased2 05/37] khugepaged: recheck pmd after mmap_sem  re-acquired Ebru Akagunduz <ebru.akagunduz@gmail.com> - 2016-06-16 13:50 +0200
        Re: [PATCHv9-rebased2 05/37] khugepaged: recheck pmd after mmap_sem  re-acquired "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-06-16 14:00 +0200
    [PATCHv9-rebased2 12/37] thp, vmstats: add counters for huge file pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 17/37] thp: prepare change_huge_pmd() for file thp "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 09/37] mm: postpone page table allocation until we have page to map "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 18/37] thp: run vma_adjust_trans_huge() outside i_mmap_rwsem "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 21/37] vmscan: split file huge pages before paging them out "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 13/37] thp: support file pages in zap_huge_pmd() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 29/37] shmem: add huge pages support "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 06/37] thp, mlock: update unevictable-lru.txt "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 19/37] thp: file pages support for split_huge_page() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 28/37] shmem: get_unmapped_area align huge page "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 07/37] mm: do not pass mm_struct into handle_mm_fault "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 34/37] khugepaged: add support of collapse for tmpfs/shmem pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 14/37] thp: handle file pages in split_huge_pmd() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 11/37] mm: introduce do_set_pmd() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 26/37] mm, rmap: account shmem thp pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 25/37] truncate: handle file thp "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 24/37] filemap: prepare find and delete operations for huge pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 22/37] page-flags: relax policy for PG_mappedtodisk and PG_reclaim "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 27/37] shmem: prepare huge= mount option and sysfs knob "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 10/37] rmap: support file thp "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:20 +0200
    [PATCHv9-rebased2 04/37]  mm-thp-make-swapin-readahead-under-down_read-of-mmap_sem-fix-2-fix "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-06-15 22:30 +0200

Page 2 of 2 — ← Prev page 1 [2]

#1423402 — [PATCHv9-rebased2 24/37] filemap: prepare find and delete operations for huge pages

For now, we would have HPAGE_PMD_NR entries in radix tree for every huge
page. That's suboptimal and it will be changed to use Matthew's
multi-order entries later.

'add' operation is not changed, because we don't need it to implement
hugetmpfs: shmem uses its own implementation.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 mm/filemap.c | 178 ++++++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 122 insertions(+), 56 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 1efd2994dccf..21508ea25717 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -114,14 +114,14 @@ static void page_cache_tree_delete(struct address_space *mapping,
 				   struct page *page, void *shadow)
 {
 	struct radix_tree_node *node;
+	int i, nr = PageHuge(page) ? 1 : hpage_nr_pages(page);
 
-	VM_BUG_ON(!PageLocked(page));
-
-	node = radix_tree_replace_clear_tags(&mapping->page_tree, page->index,
-								shadow);
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	VM_BUG_ON_PAGE(PageTail(page), page);
+	VM_BUG_ON_PAGE(nr != 1 && shadow, page);
 
 	if (shadow) {
-		mapping->nrexceptional++;
+		mapping->nrexceptional += nr;
 		/*
 		 * Make sure the nrexceptional update is committed before
 		 * the nrpages update so that final truncate racing
@@ -130,31 +130,38 @@ static void page_cache_tree_delete(struct address_space *mapping,
 		 */
 		smp_wmb();
 	}
-	mapping->nrpages--;
-
-	if (!node)
-		return;
+	mapping->nrpages -= nr;
 
-	workingset_node_pages_dec(node);
-	if (shadow)
-		workingset_node_shadows_inc(node);
-	else
-		if (__radix_tree_delete_node(&mapping->page_tree, node))
+	for (i = 0; i < nr; i++) {
+		node = radix_tree_replace_clear_tags(&mapping->page_tree,
+				page->index + i, shadow);
+		if (!node) {
+			VM_BUG_ON_PAGE(nr != 1, page);
 			return;
+		}
 
-	/*
-	 * Track node that only contains shadow entries. DAX mappings contain
-	 * no shadow entries and may contain other exceptional entries so skip
-	 * those.
-	 *
-	 * Avoid acquiring the list_lru lock if already tracked.  The
-	 * list_empty() test is safe as node->private_list is
-	 * protected by mapping->tree_lock.
-	 */
-	if (!dax_mapping(mapping) && !workingset_node_pages(node) &&
-	    list_empty(&node->private_list)) {
-		node->private_data = mapping;
-		list_lru_add(&workingset_shadow_nodes, &node->private_list);
+		workingset_node_pages_dec(node);
+		if (shadow)
+			workingset_node_shadows_inc(node);
+		else
+			if (__radix_tree_delete_node(&mapping->page_tree, node))
+				continue;
+
+		/*
+		 * Track node that only contains shadow entries. DAX mappings
+		 * contain no shadow entries and may contain other exceptional
+		 * entries so skip those.
+		 *
+		 * Avoid acquiring the list_lru lock if already tracked.
+		 * The list_empty() test is safe as node->private_list is
+		 * protected by mapping->tree_lock.
+		 */
+		if (!dax_mapping(mapping) && !workingset_node_pages(node) &&
+				list_empty(&node->private_list)) {
+			node->private_data = mapping;
+			list_lru_add(&workingset_shadow_nodes,
+					&node->private_list);
+		}
 	}
 }
 
@@ -166,6 +173,7 @@ static void page_cache_tree_delete(struct address_space *mapping,
 void __delete_from_page_cache(struct page *page, void *shadow)
 {
 	struct address_space *mapping = page->mapping;
+	int nr = hpage_nr_pages(page);
 
 	trace_mm_filemap_delete_from_page_cache(page);
 	/*
@@ -178,6 +186,7 @@ void __delete_from_page_cache(struct page *page, void *shadow)
 	else
 		cleancache_invalidate_page(mapping, page);
 
+	VM_BUG_ON_PAGE(PageTail(page), page);
 	VM_BUG_ON_PAGE(page_mapped(page), page);
 	if (!IS_ENABLED(CONFIG_DEBUG_VM) && unlikely(page_mapped(page))) {
 		int mapcount;
@@ -209,9 +218,9 @@ void __delete_from_page_cache(struct page *page, void *shadow)
 
 	/* hugetlb pages do not participate in page cache accounting. */
 	if (!PageHuge(page))
-		__dec_zone_page_state(page, NR_FILE_PAGES);
+		__mod_zone_page_state(page_zone(page), NR_FILE_PAGES, -nr);
 	if (PageSwapBacked(page))
-		__dec_zone_page_state(page, NR_SHMEM);
+		__mod_zone_page_state(page_zone(page), NR_SHMEM, -nr);
 
 	/*
 	 * At this point page must be either written or cleaned by truncate.
@@ -235,9 +244,8 @@ void __delete_from_page_cache(struct page *page, void *shadow)
  */
 void delete_from_page_cache(struct page *page)
 {
-	struct address_space *mapping = page->mapping;
+	struct address_space *mapping = page_mapping(page);
 	unsigned long flags;
-
 	void (*freepage)(struct page *);
 
 	BUG_ON(!PageLocked(page));
@@ -250,7 +258,13 @@ void delete_from_page_cache(struct page *page)
 
 	if (freepage)
 		freepage(page);
-	put_page(page);
+
+	if (PageTransHuge(page) && !PageHuge(page)) {
+		page_ref_sub(page, HPAGE_PMD_NR);
+		VM_BUG_ON_PAGE(page_count(page) <= 0, page);
+	} else {
+		put_page(page);
+	}
 }
 EXPORT_SYMBOL(delete_from_page_cache);
 
@@ -1053,7 +1067,7 @@ EXPORT_SYMBOL(page_cache_prev_hole);
 struct page *find_get_entry(struct address_space *mapping, pgoff_t offset)
 {
 	void **pagep;
-	struct page *page;
+	struct page *head, *page;
 
 	rcu_read_lock();
 repeat:
@@ -1073,8 +1087,16 @@ repeat:
 			 */
 			goto out;
 		}
-		if (!page_cache_get_speculative(page))
+
+		head = compound_head(page);
+		if (!page_cache_get_speculative(head))
+			goto repeat;
+
+		/* The page was split under us? */
+		if (compound_head(page) != head) {
+			put_page(head);
 			goto repeat;
+		}
 
 		/*
 		 * Has the page moved?
@@ -1082,7 +1104,7 @@ repeat:
 		 * include/linux/pagemap.h for details.
 		 */
 		if (unlikely(page != *pagep)) {
-			put_page(page);
+			put_page(head);
 			goto repeat;
 		}
 	}
@@ -1118,12 +1140,12 @@ repeat:
 	if (page && !radix_tree_exception(page)) {
 		lock_page(page);
 		/* Has the page been truncated? */
-		if (unlikely(page->mapping != mapping)) {
+		if (unlikely(page_mapping(page) != mapping)) {
 			unlock_page(page);
 			put_page(page);
 			goto repeat;
 		}
-		VM_BUG_ON_PAGE(page->index != offset, page);
+		VM_BUG_ON_PAGE(page_to_pgoff(page) != offset, page);
 	}
 	return page;
 }
@@ -1255,7 +1277,7 @@ unsigned find_get_entries(struct address_space *mapping,
 
 	rcu_read_lock();
 	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
-		struct page *page;
+		struct page *head, *page;
 repeat:
 		page = radix_tree_deref_slot(slot);
 		if (unlikely(!page))
@@ -1272,12 +1294,20 @@ repeat:
 			 */
 			goto export;
 		}
-		if (!page_cache_get_speculative(page))
+
+		head = compound_head(page);
+		if (!page_cache_get_speculative(head))
+			goto repeat;
+
+		/* The page was split under us? */
+		if (compound_head(page) != head) {
+			put_page(head);
 			goto repeat;
+		}
 
 		/* Has the page moved? */
 		if (unlikely(page != *slot)) {
-			put_page(page);
+			put_page(head);
 			goto repeat;
 		}
 export:
@@ -1318,7 +1348,7 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
 
 	rcu_read_lock();
 	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
-		struct page *page;
+		struct page *head, *page;
 repeat:
 		page = radix_tree_deref_slot(slot);
 		if (unlikely(!page))
@@ -1337,12 +1367,19 @@ repeat:
 			continue;
 		}
 
-		if (!page_cache_get_speculative(page))
+		head = compound_head(page);
+		if (!page_cache_get_speculative(head))
+			goto repeat;
+
+		/* The page was split under us? */
+		if (compound_head(page) != head) {
+			put_page(head);
 			goto repeat;
+		}
 
 		/* Has the page moved? */
 		if (unlikely(page != *slot)) {
-			put_page(page);
+			put_page(head);
 			goto repeat;
 		}
 
@@ -1379,7 +1416,7 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
 
 	rcu_read_lock();
 	radix_tree_for_each_contig(slot, &mapping->page_tree, &iter, index) {
-		struct page *page;
+		struct page *head, *page;
 repeat:
 		page = radix_tree_deref_slot(slot);
 		/* The hole, there no reason to continue */
@@ -1399,12 +1436,19 @@ repeat:
 			break;
 		}
 
-		if (!page_cache_get_speculative(page))
+		head = compound_head(page);
+		if (!page_cache_get_speculative(head))
+			goto repeat;
+
+		/* The page was split under us? */
+		if (compound_head(page) != head) {
+			put_page(head);
 			goto repeat;
+		}
 
 		/* Has the page moved? */
 		if (unlikely(page != *slot)) {
-			put_page(page);
+			put_page(head);
 			goto repeat;
 		}
 
@@ -1413,7 +1457,7 @@ repeat:
 		 * otherwise we can get both false positives and false
 		 * negatives, which is just confusing to the caller.
 		 */
-		if (page->mapping == NULL || page->index != iter.index) {
+		if (page->mapping == NULL || page_to_pgoff(page) != iter.index) {
 			put_page(page);
 			break;
 		}
@@ -1451,7 +1495,7 @@ unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
 	rcu_read_lock();
 	radix_tree_for_each_tagged(slot, &mapping->page_tree,
 				   &iter, *index, tag) {
-		struct page *page;
+		struct page *head, *page;
 repeat:
 		page = radix_tree_deref_slot(slot);
 		if (unlikely(!page))
@@ -1476,12 +1520,19 @@ repeat:
 			continue;
 		}
 
-		if (!page_cache_get_speculative(page))
+		head = compound_head(page);
+		if (!page_cache_get_speculative(head))
 			goto repeat;
 
+		/* The page was split under us? */
+		if (compound_head(page) != head) {
+			put_page(head);
+			goto repeat;
+		}
+
 		/* Has the page moved? */
 		if (unlikely(page != *slot)) {
-			put_page(page);
+			put_page(head);
 			goto repeat;
 		}
 
@@ -1525,7 +1576,7 @@ unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start,
 	rcu_read_lock();
 	radix_tree_for_each_tagged(slot, &mapping->page_tree,
 				   &iter, start, tag) {
-		struct page *page;
+		struct page *head, *page;
 repeat:
 		page = radix_tree_deref_slot(slot);
 		if (unlikely(!page))
@@ -1543,12 +1594,20 @@ repeat:
 			 */
 			goto export;
 		}
-		if (!page_cache_get_speculative(page))
+
+		head = compound_head(page);
+		if (!page_cache_get_speculative(head))
 			goto repeat;
 
+		/* The page was split under us? */
+		if (compound_head(page) != head) {
+			put_page(head);
+			goto repeat;
+		}
+
 		/* Has the page moved? */
 		if (unlikely(page != *slot)) {
-			put_page(page);
+			put_page(head);
 			goto repeat;
 		}
 export:
@@ -2137,7 +2196,7 @@ void filemap_map_pages(struct fault_env *fe,
 	struct address_space *mapping = file->f_mapping;
 	pgoff_t last_pgoff = start_pgoff;
 	loff_t size;
-	struct page *page;
+	struct page *head, *page;
 
 	rcu_read_lock();
 	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter,
@@ -2156,12 +2215,19 @@ repeat:
 			goto next;
 		}
 
-		if (!page_cache_get_speculative(page))
+		head = compound_head(page);
+		if (!page_cache_get_speculative(head))
 			goto repeat;
 
+		/* The page was split under us? */
+		if (compound_head(page) != head) {
+			put_page(head);
+			goto repeat;
+		}
+
 		/* Has the page moved? */
 		if (unlikely(page != *slot)) {
-			put_page(page);
+			put_page(head);
 			goto repeat;
 		}
 
-- 
2.8.1

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#1423403 — [PATCHv9-rebased2 22/37] 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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#1423404 — [PATCHv9-rebased2 27/37] 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 24c08b44724b..ac466e5d1bc7 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -442,6 +442,9 @@ 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 24463b67b6ef..2051e0685a43 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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#1423405 — [PATCHv9-rebased2 10/37] 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 51294c0d04e1..05088abe7576 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3312,18 +3312,22 @@ 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 b23f5bf9803c..02a5491f0f17 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;
@@ -2963,7 +2963,7 @@ 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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#1423410 — [PATCHv9-rebased2 04/37] mm-thp-make-swapin-readahead-under-down_read-of-mmap_sem-fix-2-fix

From: Andrew Morton <akpm@linux-foundation.org>

update comment to match new code

Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/huge_memory.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 1777b806de96..d7ccc8558187 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2502,9 +2502,9 @@ static void collapse_huge_page(struct mm_struct *mm,
 	}
 
 	/*
-	 * __collapse_huge_page_swapin always returns with mmap_sem
-	 * locked. If it fails, release mmap_sem and jump directly
-	 * label out. Continuing to collapse causes inconsistency.
+	 * __collapse_huge_page_swapin always returns with mmap_sem locked.
+	 * If it fails, release mmap_sem and jump directly out.
+	 * Continuing to collapse causes inconsistency.
 	 */
 	if (!__collapse_huge_page_swapin(mm, vma, address, pmd)) {
 		mem_cgroup_cancel_charge(new_page, memcg, true);
-- 
2.8.1

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