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| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2016-04-29 01:18:27 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-04-29 04:34:04 +0200 |
| commit | aa88b68c3b1dce8bc3fd54c8a7372a777ff265cd (patch) | |
| tree | 98ad92a044b6a2f39a8fa4c1c24df001108bd1a8 /mm/huge_memory.c | |
| parent | mm: exclude HugeTLB pages from THP page_mapped() logic (diff) | |
| download | linux-aa88b68c3b1dce8bc3fd54c8a7372a777ff265cd.tar.xz linux-aa88b68c3b1dce8bc3fd54c8a7372a777ff265cd.zip | |
thp: keep huge zero page pinned until tlb flush
Andrea has found[1] a race condition on MMU-gather based TLB flush vs
split_huge_page() or shrinker which frees huge zero under us (patch 1/2
and 2/2 respectively).
With new THP refcounting, we don't need patch 1/2: mmu_gather keeps the
page pinned until flush is complete and the pin prevents the page from
being split under us.
We still need patch 2/2. This is simplified version of Andrea's patch.
We don't need fancy encoding.
[1] http://lkml.kernel.org/r/1447938052-22165-1-git-send-email-aarcange@redhat.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 86f9f8b82f8e..5346de05f471 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -232,7 +232,7 @@ retry: return READ_ONCE(huge_zero_page); } -static void put_huge_zero_page(void) +void put_huge_zero_page(void) { /* * Counter should never go to zero here. Only shrinker can put @@ -1684,12 +1684,12 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, if (vma_is_dax(vma)) { spin_unlock(ptl); if (is_huge_zero_pmd(orig_pmd)) - put_huge_zero_page(); + tlb_remove_page(tlb, pmd_page(orig_pmd)); } else if (is_huge_zero_pmd(orig_pmd)) { pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd)); atomic_long_dec(&tlb->mm->nr_ptes); spin_unlock(ptl); - put_huge_zero_page(); + tlb_remove_page(tlb, pmd_page(orig_pmd)); } else { struct page *page = pmd_page(orig_pmd); page_remove_rmap(page, true); |