Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1416032

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

Show all headers | View raw

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

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[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

csiph-web