Messages in this thread Patch in this message | | | Date | Wed, 9 Jun 2010 21:16:17 -0400 | From | Rik van Riel <> | Subject | [PATCH -mm] only drop root anon_vma if not self |
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On Wed, 9 Jun 2010 17:19:02 +0800 Dave Young <hidave.darkstar@gmail.com> wrote:
> > Manually bisected mm patches, the memleak caused by following patch: > > > > mm-extend-ksm-refcounts-to-the-anon_vma-root.patch > > > So I guess the refcount break, either drop-without-get or over-drop
I'm guessing I did not run the kernel with enough debug options enabled when I tested my patches...
Dave & Catalin, thank you for tracking this down.
Dave, does the below patch fix your issue?
Andrew, if the patch below works, you'll probably want to merge it as mm-extend-ksm-refcounts-to-the-anon_vma-root-fix.patch :)
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With the new anon_vma code we take a refcount on the root anon_vma. However, the root anon_vma does not have a refcount on itself, so we should not try to do a drop on itself when it is being unlinked.
Signed-off-by: Rik van Riel <riel@redhat.com>
--- linux-2.6-rtavma/mm/rmap.c.orig 2010-06-09 21:10:07.349376896 -0400 +++ linux-2.6-rtavma/mm/rmap.c 2010-06-09 21:10:24.180406299 -0400 @@ -275,7 +275,8 @@ static void anon_vma_unlink(struct anon_ if (empty) { /* We no longer need the root anon_vma */ - drop_anon_vma(anon_vma->root); + if (anon_vma->root != anon_vma) + drop_anon_vma(anon_vma->root); anon_vma_free(anon_vma); } }
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