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| author | Andrea Arcangeli <aarcange@redhat.com> | 2012-09-28 14:35:31 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-09-28 08:38:09 -0700 |
| commit | 99a1300e1d84709f419182bb5189760e78234882 (patch) | |
| tree | 1d3cc49d4015fbb2b3d5bbeed313d30d7756526b /mm | |
| parent | 63994137eb53bb0fc42ad180c0ce509d3eb3bdc9 (diff) | |
| download | linux-99a1300e1d84709f419182bb5189760e78234882.tar.bz2 | |
thp: avoid VM_BUG_ON page_count(page) false positives in __collapse_huge_page_copy
Speculative cache pagecache lookups can elevate the refcount from
under us, so avoid the false positive. If the refcount is < 2 we'll be
notified by a VM_BUG_ON in put_page_testzero as there are two
put_page(src_page) in a row before returning from this function.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Petr Holasek <pholasek@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/huge_memory.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 57c4b9309015..141dbb695097 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1811,7 +1811,6 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page, src_page = pte_page(pteval); copy_user_highpage(page, src_page, address, vma); VM_BUG_ON(page_mapcount(src_page) != 1); - VM_BUG_ON(page_count(src_page) != 2); release_pte_page(src_page); /* * ptl mostly unnecessary, but preempt has to |