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rmap: fix walk during fork 

The below bug in fork led to the rmap walk finding the parent huge-pmd
twice instead of just once, because the anon_vma_chain objects of the
child vma still point to the vma->vm_mm of the parent.

The patch fixes it by making the rmap walk accurate during fork.  It's not
a big deal normally but it worth being accurate considering the cost is
the same.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrea Arcangeli 2010-09-22 13:05:12 -07:00 committed by Linus Torvalds
parent df08cdc7ef
commit a247c3a97a
1 changed files with 1 additions and 1 deletions
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2
kernel/fork.c
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@ -356,10 +356,10 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
if (IS_ERR(pol)) if (IS_ERR(pol))
goto fail_nomem_policy; goto fail_nomem_policy;
vma_set_policy(tmp, pol); vma_set_policy(tmp, pol);
tmp->vm_mm = mm;
if (anon_vma_fork(tmp, mpnt)) if (anon_vma_fork(tmp, mpnt))
goto fail_nomem_anon_vma_fork; goto fail_nomem_anon_vma_fork;
tmp->vm_flags &= ~VM_LOCKED; tmp->vm_flags &= ~VM_LOCKED;
tmp->vm_mm = mm;
tmp->vm_next = tmp->vm_prev = NULL; tmp->vm_next = tmp->vm_prev = NULL;
file = tmp->vm_file; file = tmp->vm_file;
if (file) { if (file) {