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authorMichel Lespinasse <walken@google.com>2012-10-08 16:31:36 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-09 16:22:41 +0900
commit108d6642ad81bb1d62b401490a334d2c12397517 (patch)
tree27df7d1777d80b9dddeaefaac928b726ff82a816 /mm/mmap.c
parent9826a516ff77c5820e591211e4f3e58ff36f46be (diff)
mm anon rmap: remove anon_vma_moveto_tail
mremap() had a clever optimization where move_ptes() did not take the anon_vma lock to avoid a race with anon rmap users such as page migration. Instead, the avc's were ordered in such a way that the origin vma was always visited by rmap before the destination. This ordering and the use of page table locks rmap usage safe. However, we want to replace the use of linked lists in anon rmap with an interval tree, and this will make it harder to impose such ordering as the interval tree will always be sorted by the avc->vma->vm_pgoff value. For now, let's replace the anon_vma_moveto_tail() ordering function with proper anon_vma locking in move_ptes(). Once we have the anon interval tree in place, we will re-introduce an optimization to avoid taking these locks in the most common cases. Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mmap.c')
-rw-r--r--mm/mmap.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index 5ac533f88e9..66984aab791 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2378,8 +2378,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
*/
VM_BUG_ON(faulted_in_anon_vma);
*vmap = new_vma;
- } else
- anon_vma_moveto_tail(new_vma);
+ }
} else {
new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
if (new_vma) {