On 05/12/2010 08:38 PM, KAMEZAWA Hiroyuki wrote:
On Wed, 12 May 2010 13:39:58 -0400
Rik van Riel<riel@xxxxxxxxxx> wrote:
Subject: track the root (oldest) anon_vma
Track the root (oldest) anon_vma in each anon_vma tree. Because we only
take the lock on the root anon_vma, we cannot use the lock on higher-up
anon_vmas to lock anything. This makes it impossible to do an indirect
lookup of the root anon_vma, since the data structures could go away from
under us.
However, a direct pointer is safe because the root anon_vma is always the
last one that gets freed on munmap or exit, by virtue of the same_vma list
order and unlink_anon_vmas walking the list forward.
Signed-off-by: Rik van Riel<riel@xxxxxxxxxx>
Acked-by: KAMEZAWA Hiroyuki<kamezawa.hiroyu@xxxxxxxxxxxxxx>
I welcome this. Thank you!
Reading 4/5, I felt I'm grad if you add a Documentation or very-precise-comment
about the new anon_vma rules and the _meaning_ of anon_vma_root_lock.
I cannot fully convice myself that I understand them all.
Please send me a list of all the questions that come up
when you read the patches, and I'll prepare a patch 6/5
with just documentation :)
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