From: Oleg Nesterov <oleg@redhat.com>
To: Hugh Dickins <hughd@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>,
Kautuk Consul <consul.kautuk@gmail.com>,
Ingo Molnar <mingo@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.cz>,
David Rientjes <rientjes@google.com>,
Ionut Alexa <ionut.m.alexa@gmail.com>,
Guillaume Morin <guillaume@morinfr.org>,
linux-kernel@vger.kernel.org, Kirill Tkhai <tkhai@yandex.ru>
Subject: Re: task_numa_fault() && TASK_DEAD
Date: Fri, 5 Sep 2014 13:35:53 +0200 [thread overview]
Message-ID: <20140905113553.GA24717@redhat.com> (raw)
In-Reply-To: <alpine.LSU.2.11.1409041210400.12218@eggly.anvils>
On 09/04, Hugh Dickins wrote:
>
> On Thu, 4 Sep 2014, Oleg Nesterov wrote:
> > On 09/04, Peter Zijlstra wrote:
> > > On Wed, Sep 03, 2014 at 06:08:19PM +0200, Oleg Nesterov wrote:
> > >
> > > > And a stupid (really, I don't understand this code) question:
> > > >
> > > > /* for example, ksmd faulting in a user's mm */
> > > > if (!p->mm)
> > > > return;
>
> I don't understand your difficulty with that, I thought the comment
> was helpful enough.
Yes, yes, sorry for confusion, the comment and the check itself look clear.
> Does the original commit comment help?
>
> commit 2832bc19f6668fd00116f61f821105040599ef8b
> Author: Hugh Dickins <hughd@google.com>
> Date: Wed Dec 19 17:42:16 2012 -0800
>
> sched: numa: ksm: fix oops in task_numa_placment()
>
> task_numa_placement() oopsed on NULL p->mm
Yes. But I thought that even if task_numa_placment() didn't OOPS in case
when ->mm = NULL, it would be better to exclude ksmd. And other kthreads
which can have ->mm != NULL, and PTRACE_POKE or sys_process_vm_writev()
users:
/* do nothing if this task accesses a foreign mm */
if (p->mm != mm || (p->flags & PF_KTHREAD)
return;
Please forget. This is minor, and my main question was the wrong usage
of TASK_DEAD.
Oleg.
next prev parent reply other threads:[~2014-09-05 11:38 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-25 10:54 [PATCH 1/1] do_exit(): Solve possibility of BUG() due to race with try_to_wake_up() Kautuk Consul
2014-08-25 15:57 ` Oleg Nesterov
2014-08-26 4:45 ` Kautuk Consul
2014-08-26 15:03 ` Oleg Nesterov
2014-09-01 15:39 ` Peter Zijlstra
2014-09-01 17:58 ` Oleg Nesterov
2014-09-01 19:09 ` Peter Zijlstra
2014-09-02 15:52 ` Oleg Nesterov
2014-09-02 16:47 ` Oleg Nesterov
2014-09-02 17:39 ` Peter Zijlstra
2014-09-03 13:36 ` Oleg Nesterov
2014-09-03 14:44 ` Peter Zijlstra
2014-09-03 15:18 ` Oleg Nesterov
2014-09-04 7:15 ` Peter Zijlstra
2014-09-04 17:03 ` Paul E. McKenney
2014-09-04 5:04 ` Ingo Molnar
2014-09-04 6:32 ` Peter Zijlstra
2014-09-03 16:08 ` task_numa_fault() && TASK_DEAD Oleg Nesterov
2014-09-03 16:33 ` Rik van Riel
2014-09-04 7:11 ` Peter Zijlstra
2014-09-04 10:39 ` Oleg Nesterov
2014-09-04 19:14 ` Hugh Dickins
2014-09-05 11:35 ` Oleg Nesterov [this message]
2014-09-03 9:04 ` [PATCH 1/1] do_exit(): Solve possibility of BUG() due to race with try_to_wake_up() Kirill Tkhai
2014-09-03 9:45 ` Peter Zijlstra
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