From: Rik van Riel <riel@redhat.com>
To: Konstantin Khlebnikov <koct9i@gmail.com>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org
Cc: "Elifaz, Dana" <Dana.Elifaz@amd.com>,
"Bridgman, John" <John.Bridgman@amd.com>,
Daniel Forrest <dan.forrest@ssec.wisc.edu>,
Chris Clayton <chris2553@googlemail.com>,
Oded Gabbay <oded.gabbay@amd.com>, Michal Hocko <mhocko@suse.cz>
Subject: Re: [PATCH] mm: fix corner case in anon_vma endless growing prevention
Date: Sun, 11 Jan 2015 09:25:02 -0500 [thread overview]
Message-ID: <54B287BE.3010107@redhat.com> (raw)
In-Reply-To: <20150111135406.13266.42007.stgit@zurg>
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On 01/11/2015 08:54 AM, Konstantin Khlebnikov wrote:
> Fix for BUG_ON(anon_vma->degree) splashes in unlink_anon_vmas()
> ("kernel BUG at mm/rmap.c:399!").
>
> Anon_vma_clone() is usually called for a copy of source vma in
> destination argument. If source vma has anon_vma it should be
> already in dst->anon_vma. NULL in dst->anon_vma is used as a sign
> that it's called from anon_vma_fork(). In this case
> anon_vma_clone() finds anon_vma for reusing.
>
> Vma_adjust() calls it differently and this breaks anon_vma reusing
> logic: anon_vma_clone() links vma to old anon_vma and updates
> degree counters but vma_adjust() overrides vma->anon_vma right
> after that. As a result final unlink_anon_vmas() decrements degree
> for wrong anon_vma.
>
> This patch assigns ->anon_vma before calling anon_vma_clone().
>
> Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com> Fixes:
> 7a3ef208e662 ("mm: prevent endless growth of anon_vma hierarchy")
> Tested-by: Chris Clayton <chris2553@googlemail.com> Tested-by: Oded
> Gabbay <oded.gabbay@amd.com> Cc: Daniel Forrest
> <dan.forrest@ssec.wisc.edu> Cc: Michal Hocko <mhocko@suse.cz> Cc:
> Rik van Riel <riel@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
- --
All rights reversed
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WARNING: multiple messages have this Message-ID (diff)
From: Rik van Riel <riel@redhat.com>
To: Konstantin Khlebnikov <koct9i@gmail.com>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org
Cc: "Elifaz, Dana" <Dana.Elifaz@amd.com>,
"Bridgman, John" <John.Bridgman@amd.com>,
Daniel Forrest <dan.forrest@ssec.wisc.edu>,
Chris Clayton <chris2553@googlemail.com>,
Oded Gabbay <oded.gabbay@amd.com>, Michal Hocko <mhocko@suse.cz>
Subject: Re: [PATCH] mm: fix corner case in anon_vma endless growing prevention
Date: Sun, 11 Jan 2015 09:25:02 -0500 [thread overview]
Message-ID: <54B287BE.3010107@redhat.com> (raw)
In-Reply-To: <20150111135406.13266.42007.stgit@zurg>
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On 01/11/2015 08:54 AM, Konstantin Khlebnikov wrote:
> Fix for BUG_ON(anon_vma->degree) splashes in unlink_anon_vmas()
> ("kernel BUG at mm/rmap.c:399!").
>
> Anon_vma_clone() is usually called for a copy of source vma in
> destination argument. If source vma has anon_vma it should be
> already in dst->anon_vma. NULL in dst->anon_vma is used as a sign
> that it's called from anon_vma_fork(). In this case
> anon_vma_clone() finds anon_vma for reusing.
>
> Vma_adjust() calls it differently and this breaks anon_vma reusing
> logic: anon_vma_clone() links vma to old anon_vma and updates
> degree counters but vma_adjust() overrides vma->anon_vma right
> after that. As a result final unlink_anon_vmas() decrements degree
> for wrong anon_vma.
>
> This patch assigns ->anon_vma before calling anon_vma_clone().
>
> Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com> Fixes:
> 7a3ef208e662 ("mm: prevent endless growth of anon_vma hierarchy")
> Tested-by: Chris Clayton <chris2553@googlemail.com> Tested-by: Oded
> Gabbay <oded.gabbay@amd.com> Cc: Daniel Forrest
> <dan.forrest@ssec.wisc.edu> Cc: Michal Hocko <mhocko@suse.cz> Cc:
> Rik van Riel <riel@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
- --
All rights reversed
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next prev parent reply other threads:[~2015-01-11 14:25 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-11 13:54 [PATCH] mm: fix corner case in anon_vma endless growing prevention Konstantin Khlebnikov
2015-01-11 13:54 ` Konstantin Khlebnikov
2015-01-11 14:25 ` Rik van Riel [this message]
2015-01-11 14:25 ` Rik van Riel
2015-01-11 15:05 ` Vlastimil Babka
2015-01-11 15:05 ` Vlastimil Babka
2015-01-12 9:50 ` Michal Hocko
2015-01-12 9:50 ` Michal Hocko
2015-01-12 20:21 ` Andrew Morton
2015-01-12 20:21 ` Andrew Morton
2015-01-13 6:53 ` Konstantin Khlebnikov
2015-01-13 6:53 ` Konstantin Khlebnikov
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