From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: mgorman@suse.de
Cc: akpm@linux-foundation.org, kosaki.motohiro@jp.fujitsu.com,
davej@redhat.com, cl@linux.com, ben@decadent.org.uk,
ak@linux.intel.com, hughd@google.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 3/5] mempolicy: fix a race in shared_policy_replace()
Date: Fri, 07 Sep 2012 18:59:40 -0400 [thread overview]
Message-ID: <504A7C5C.1000706@jp.fujitsu.com> (raw)
In-Reply-To: <1345480594-27032-4-git-send-email-mgorman@suse.de>
First off, thank you very much for reworking this for me. I haven't got a chance
to get a test machine for this.
> shared_policy_replace() use of sp_alloc() is unsafe. 1) sp_node cannot
> be dereferenced if sp->lock is not held and 2) another thread can modify
> sp_node between spin_unlock for allocating a new sp node and next spin_lock.
> The bug was introduced before 2.6.12-rc2.
>
> Kosaki's original patch for this problem was to allocate an sp node and policy
> within shared_policy_replace and initialise it when the lock is reacquired. I
> was not keen on this approach because it partially duplicates sp_alloc(). As
> the paths were sp->lock is taken are not that performance critical this
> patch converts sp->lock to sp->mutex so it can sleep when calling sp_alloc().
Looks make sense.
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
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WARNING: multiple messages have this Message-ID (diff)
From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: mgorman@suse.de
Cc: akpm@linux-foundation.org, kosaki.motohiro@jp.fujitsu.com,
davej@redhat.com, cl@linux.com, ben@decadent.org.uk,
ak@linux.intel.com, hughd@google.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 3/5] mempolicy: fix a race in shared_policy_replace()
Date: Fri, 07 Sep 2012 18:59:40 -0400 [thread overview]
Message-ID: <504A7C5C.1000706@jp.fujitsu.com> (raw)
In-Reply-To: <1345480594-27032-4-git-send-email-mgorman@suse.de>
First off, thank you very much for reworking this for me. I haven't got a chance
to get a test machine for this.
> shared_policy_replace() use of sp_alloc() is unsafe. 1) sp_node cannot
> be dereferenced if sp->lock is not held and 2) another thread can modify
> sp_node between spin_unlock for allocating a new sp node and next spin_lock.
> The bug was introduced before 2.6.12-rc2.
>
> Kosaki's original patch for this problem was to allocate an sp node and policy
> within shared_policy_replace and initialise it when the lock is reacquired. I
> was not keen on this approach because it partially duplicates sp_alloc(). As
> the paths were sp->lock is taken are not that performance critical this
> patch converts sp->lock to sp->mutex so it can sleep when calling sp_alloc().
Looks make sense.
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
next prev parent reply other threads:[~2012-09-07 22:59 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-20 16:36 [PATCH 0/5] Memory policy corruption fixes V2 Mel Gorman
2012-08-20 16:36 ` Mel Gorman
2012-08-20 16:36 ` [PATCH 1/5] Revert "mm: mempolicy: Let vma_merge and vma_split handle vma->vm_policy linkages" Mel Gorman
2012-08-20 16:36 ` Mel Gorman
2012-08-20 16:36 ` [PATCH 2/5] mempolicy: Remove mempolicy sharing Mel Gorman
2012-08-20 16:36 ` Mel Gorman
2012-08-20 19:35 ` Christoph Lameter
2012-08-20 19:35 ` Christoph Lameter
2012-08-22 19:03 ` Andrew Morton
2012-08-22 19:03 ` Andrew Morton
2012-08-22 19:33 ` Mel Gorman
2012-08-22 19:33 ` Mel Gorman
2012-08-22 19:35 ` Andi Kleen
2012-08-22 19:35 ` Andi Kleen
2012-08-20 16:36 ` [PATCH 3/5] mempolicy: fix a race in shared_policy_replace() Mel Gorman
2012-08-20 16:36 ` Mel Gorman
2012-08-20 19:52 ` Christoph Lameter
2012-08-20 19:52 ` Christoph Lameter
2012-09-07 22:59 ` KOSAKI Motohiro [this message]
2012-09-07 22:59 ` KOSAKI Motohiro
2012-08-20 16:36 ` [PATCH 4/5] mempolicy: fix refcount leak in mpol_set_shared_policy() Mel Gorman
2012-08-20 16:36 ` Mel Gorman
2012-08-20 19:46 ` Christoph Lameter
2012-08-20 19:46 ` Christoph Lameter
2012-08-21 7:15 ` Mel Gorman
2012-08-21 7:15 ` Mel Gorman
2012-08-21 15:38 ` Christoph Lameter
2012-08-21 15:38 ` Christoph Lameter
2012-08-20 16:36 ` [PATCH 5/5] mempolicy: fix a memory corruption by refcount imbalance in alloc_pages_vma() Mel Gorman
2012-08-20 16:36 ` Mel Gorman
2012-08-20 19:51 ` Christoph Lameter
2012-08-20 19:51 ` Christoph Lameter
2012-08-21 7:26 ` Mel Gorman
2012-08-21 7:26 ` Mel Gorman
2012-08-21 15:37 ` Christoph Lameter
2012-08-21 15:37 ` Christoph Lameter
2012-09-07 23:06 ` KOSAKI Motohiro
2012-09-07 23:06 ` KOSAKI Motohiro
2012-08-21 7:29 ` [PATCH 0/5] Memory policy corruption fixes V2 Mel Gorman
2012-08-21 7:29 ` Mel Gorman
2012-09-06 12:40 ` Josh Boyer
2012-09-06 12:40 ` Josh Boyer
2012-09-07 9:43 ` Mel Gorman
2012-09-07 9:43 ` Mel Gorman
2012-08-21 21:46 ` Andi Kleen
2012-08-21 21:46 ` Andi Kleen
-- strict thread matches above, loose matches on Subject: below --
2012-10-09 16:58 [PATCH 0/5] Memory policy corruption fixes -stable Mel Gorman
2012-10-09 16:58 ` [PATCH 3/5] mempolicy: fix a race in shared_policy_replace() Mel Gorman
2012-10-09 16:58 ` Mel Gorman
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