From: Oleg Nesterov <oleg@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Mandeep Singh Baines <msb@chromium.org>,
"Ma, Xindong" <xindong.ma@intel.com>,
Michal Hocko <mhocko@suse.cz>, Sameer Nanda <snanda@chromium.org>,
Sergey Dyasly <dserrg@gmail.com>,
"Tu, Xiaobing" <xiaobing.tu@intel.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/2] initial while_each_thread() fixes
Date: Mon, 2 Dec 2013 16:34:18 +0100 [thread overview]
Message-ID: <20131202153418.GA11061@redhat.com> (raw)
In-Reply-To: <20131202152423.GA10878@redhat.com>
On 12/02, Oleg Nesterov wrote:
>
> The lockless while_each_thread() is racy and broken, almost
> every user can loop forever.
> ...
> Another problem with while_each_thread() is that it is very easy
> to use it wrongly, and oom_kill.c is the good example.
Forgot to mention, it is not necessarily safe even under task
list lock if it is used wrongly. Again, oom_kill.c is the good
example, oom_kill_process() does read_lock(&tasklist_lock) but
it doesn't verify that p is still alive.
The new for_each_thread() is much simpler in this respect, it
only needs the stable task_struct.
Oleg.
next prev parent reply other threads:[~2013-12-02 15:33 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-02 15:24 [PATCH 0/2] initial while_each_thread() fixes Oleg Nesterov
2013-12-02 15:24 ` [PATCH 1/2] introduce for_each_thread() to replace the buggy while_each_thread() Oleg Nesterov
2013-12-03 19:24 ` Sameer Nanda
2013-12-02 15:24 ` [PATCH 2/2] oom_kill: change oom_kill.c to use for_each_thread() Oleg Nesterov
2013-12-03 18:57 ` Sameer Nanda
2013-12-03 20:05 ` Oleg Nesterov
2013-12-03 20:50 ` Oleg Nesterov
2013-12-04 12:57 ` Oleg Nesterov
2013-12-02 15:34 ` Oleg Nesterov [this message]
2013-12-03 15:46 ` [PATCH 0/2] initial while_each_thread() fixes Sergey Dyasly
2013-12-03 18:52 ` Oleg Nesterov
2013-12-03 19:01 ` Oleg Nesterov
2013-12-03 16:53 ` William Dauchy
2013-12-03 20:22 ` Oleg Nesterov
2013-12-03 20:28 ` William Dauchy
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