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authorAndrea Arcangeli <aarcange@redhat.com>2011-01-13 15:46:53 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-13 17:32:42 -0800
commit05759d380a9d7f131a475186c07fce58ceaa8902 (patch)
tree6c253f15176c89f6f8dfd80b1471bcf3e0a3e44e /mm/rmap.c
parent8a07651ee8cdaa9e27cb4ae372aed347533770f5 (diff)
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thp: split_huge_page anon_vma ordering dependency
This documents how split_huge_page is safe vs new vma inserctions into the anon_vma that may have already released the anon_vma->lock but not established pmds yet when split_huge_page starts. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
-rw-r--r--mm/rmap.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index e41375a6b029..92e14dcfe737 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -177,6 +177,10 @@ static void anon_vma_chain_link(struct vm_area_struct *vma,
list_add(&avc->same_vma, &vma->anon_vma_chain);
anon_vma_lock(anon_vma);
+ /*
+ * It's critical to add new vmas to the tail of the anon_vma,
+ * see comment in huge_memory.c:__split_huge_page().
+ */
list_add_tail(&avc->same_anon_vma, &anon_vma->head);
anon_vma_unlock(anon_vma);
}