From: Johannes Weiner <hannes@cmpxchg.org>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>, Michal Hocko <mhocko@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Kyle Walker <kwalker@redhat.com>,
Christoph Lameter <cl@linux.com>,
Vladimir Davydov <vdavydov@parallels.com>,
linux-mm <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Stanislav Kozina <skozina@redhat.com>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Subject: Re: [patch] mm, oom: remove task_lock protecting comm printing
Date: Thu, 24 Sep 2015 15:45:28 -0400 [thread overview]
Message-ID: <20150924194528.GB3009@cmpxchg.org> (raw)
In-Reply-To: <alpine.DEB.2.10.1509221629440.7794@chino.kir.corp.google.com>
On Tue, Sep 22, 2015 at 04:30:13PM -0700, David Rientjes wrote:
> The oom killer takes task_lock() in a couple of places solely to protect
> printing the task's comm.
>
> A process's comm, including current's comm, may change due to
> /proc/pid/comm or PR_SET_NAME.
>
> The comm will always be NULL-terminated, so the worst race scenario would
> only be during update. We can tolerate a comm being printed that is in
> the middle of an update to avoid taking the lock.
>
> Other locations in the kernel have already dropped task_lock() when
> printing comm, so this is consistent.
>
> Suggested-by: Oleg Nesterov <oleg@redhat.com>
> Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
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prev parent reply other threads:[~2015-09-24 19:45 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-22 23:30 David Rientjes
2015-09-23 7:44 ` Michal Hocko
2015-09-23 8:06 ` Vladimir Davydov
2015-09-23 9:13 ` Sergey Senozhatsky
2015-09-23 9:30 ` Vladimir Davydov
2015-09-23 9:43 ` Michal Hocko
2015-09-23 9:50 ` Sergey Senozhatsky
2015-09-23 9:57 ` Sergey Senozhatsky
2015-09-23 10:07 ` Vladimir Davydov
2015-09-23 10:41 ` Michal Hocko
2015-09-24 19:45 ` Johannes Weiner [this message]
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