From: Glauber Costa <glommer@parallels.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>,
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 16:02:19 -0300 [thread overview]
Message-ID: <4F85D53B.1070806@parallels.com> (raw)
In-Reply-To: <CA+55aFx1GMWGgh0sTAzvvVSzPQsQ_4NKeaNv1zpKrP4fg1dG+Q@mail.gmail.com>
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.
At least in my test cases, after turning this to a WARN (to make sure it
was still being hit), the machine could go on just fine.
I was running this in a container system, with restricted memory. After
killing the container - at least in my ext4 system - everything seemed
as happy as ever.
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next prev parent reply other threads:[~2012-04-11 19:04 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 [this message]
2012-04-11 19:25 ` Michal Hocko
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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