Re: [PATCH 67 of 67] memcg fix prepare migration

From: Andrew Morton <akpm@linux-foundation.org>
To: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
	linux-mm@kvack.org, Marcelo Tosatti <mtosatti@redhat.com>,
	Adam Litke <agl@us.ibm.com>, Avi Kivity <avi@redhat.com>,
	Izik Eidus <ieidus@redhat.com>,
	Hugh Dickins <hugh.dickins@tiscali.co.uk>,
	Nick Piggin <npiggin@suse.de>, Rik van Riel <riel@redhat.com>,
	Mel Gorman <mel@csn.ul.ie>, Dave Hansen <dave@linux.vnet.ibm.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Ingo Molnar <mingo@elte.hu>, Mike Travis <travis@sgi.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Christoph Lameter <cl@linux-foundation.org>,
	Chris Wright <chrisw@sous-sol.org>,
	bpicco@redhat.com,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Balbir Singh <balbir@linux.vnet.ibm.com>,
	Arnd Bergmann <arnd@arndb.de>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Chris Mason <chris.mason@oracle.com>,
	stable@kernel.org
Subject: Re: [PATCH 67 of 67] memcg fix prepare migration
Date: Mon, 12 Apr 2010 21:29:13 -0400	[thread overview]
Message-ID: <20100412212913.55be5ce5.akpm@linux-foundation.org> (raw)
In-Reply-To: <20100408125722.2a11257d.nishimura@mxp.nes.nec.co.jp>

On Thu, 8 Apr 2010 12:57:22 +0900 Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:

> On Thu, 08 Apr 2010 03:51:50 +0200, Andrea Arcangeli <aarcange@redhat.com> wrote:
> > From: Andrea Arcangeli <aarcange@redhat.com>
> > 
> > If a signal is pending (task being killed by sigkill) __mem_cgroup_try_charge
> > will write NULL into &mem, and css_put will oops on null pointer dereference.
> > 
> > BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
> > IP: [<ffffffff810fc6cc>] mem_cgroup_prepare_migration+0x7c/0xc0
> > PGD a5d89067 PUD a5d8a067 PMD 0
> > Oops: 0000 [#1] SMP
> > last sysfs file: /sys/devices/platform/microcode/firmware/microcode/loading
> > CPU 0
> > Modules linked in: nfs lockd nfs_acl auth_rpcgss sunrpc acpi_cpufreq pcspkr sg [last unloaded: microcode]
> > 
> > Pid: 5299, comm: largepages Tainted: G        W  2.6.34-rc3 #3 Penryn1600SLI-110dB/To Be Filled By O.E.M.
> > RIP: 0010:[<ffffffff810fc6cc>]  [<ffffffff810fc6cc>] mem_cgroup_prepare_migration+0x7c/0xc0
> > 
> > Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
> Nice catch !
> 
> But I think this fix should be forwarded to 34-rc and stable. They all have
> the same problem if the "current" which is doing the page migration is being
> oom-killed.

OK.  I added the cc:stable.  The patch gets a trivial reject vs 2.6.33,
but they'll work it out ;)

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>