From: Michal Hocko <mhocko@suse.cz>
To: Glauber Costa <glommer@parallels.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org, devel@openvz.org,
linux-mm@kvack.org, cgroups@vger.kernel.org,
Johannes Weiner <hannes@cmpxchg.org>,
kamezawa.hiroyu@jp.fujitsu.com, Greg Thelen <gthelen@google.com>,
Suleiman Souhlal <suleiman@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] remove BUG() in possible but rare condition
Date: Wed, 11 Apr 2012 21:25:54 +0200 [thread overview]
Message-ID: <20120411192554.GC24831@tiehlicka.suse.cz> (raw)
In-Reply-To: <4F85D53B.1070806@parallels.com>
On Wed 11-04-12 16:02:19, Glauber Costa wrote:
> On 04/11/2012 03:57 PM, Linus Torvalds wrote:
> >On Wed, Apr 11, 2012 at 11:48 AM, Michal Hocko<mhocko@suse.cz> wrote:
> >>
> >>I am not familiar with the code much but a trivial call chain walk up to
> >>write_dev_supers (in btrfs) shows that we do not check for the return value
> >>from __getblk so we would nullptr and there might be more.
> >>I guess these need some treat before the BUG might be removed, right?
> >
> >Well, realistically, isn't BUG() as bad as a NULL pointer dereference?
> >
> >Do you care about the exact message on the screen when your machine dies?
> Not particular, but I don't see why (I might be wrong) it would
> necessarily lead to a NULL pointer dereference.
Ahh, OK scratch that. I have misread __getblk_slow which returns NULL
only if grow_buffers returned with < 0 which doesn't happen for the
allocation failure.
Sorry about noise
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
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next prev parent reply other threads:[~2012-04-11 19:25 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-11 18:10 Glauber Costa
2012-04-11 18:48 ` Michal Hocko
2012-04-11 18:57 ` Linus Torvalds
2012-04-11 19:02 ` Glauber Costa
2012-04-11 19:25 ` Michal Hocko [this message]
2012-04-11 19:20 ` Michal Hocko
2012-04-11 19:48 ` Don Morris
2012-04-11 21:33 ` Jiri Kosina
2012-04-11 18:59 ` Glauber Costa
2012-04-11 20:26 ` Andrew Morton
2012-04-11 20:51 ` Glauber Costa
2012-04-11 21:12 ` Andrew Morton
2012-04-11 21:26 ` Michal Hocko
2012-04-12 9:24 ` Michal Hocko
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