From: Tejun Heo <tj@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
David Rientjes <rientjes@google.com>,
David Laight <David.Laight@ACULAB.COM>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Ingo Molnar <mingo@kernel.org>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: oom-kill && frozen()
Date: Wed, 13 Nov 2013 12:20:53 +0900 [thread overview]
Message-ID: <20131113032053.GA19394@mtj.dyndns.org> (raw)
In-Reply-To: <20131112165643.GA31278@redhat.com>
Hello,
On Tue, Nov 12, 2013 at 05:56:43PM +0100, Oleg Nesterov wrote:
> On 11/12, Oleg Nesterov wrote:
> > I am also wondering if it makes any sense to turn PF_FROZEN into
> > TASK_FROZEN, something like (incomplete, probably racy) patch below.
> > Note that it actually adds the new state, not the the qualifier.
>
> As for the current usage of PF_FROZEN... David, it seems that
> oom_scan_process_thread()->__thaw_task() is dead? Probably this
> was fine before, when __thaw_task() cleared the "need to freeze"
> condition, iirc it was PF_FROZEN.
>
> But today __thaw_task() can't help, no? the task will simply
> schedule() in D state again.
Yeah, it'll have to be actively excluded using e.g. PF_FREEZER_SKIP,
which, BTW, can usually only be manipulated by the task itself. I've
been saying this multiple times but this is yet another cost of having
"frozen" as a separate completely alien task state, which is
essentially close to being undefined when viewed from userland. We're
spreading broken behaviors and complexity throughout the kernel by
making this half broken state visible. :(
Thanks.
--
tejun
next prev parent reply other threads:[~2013-11-13 3:21 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-12 13:53 [PATCH] ipvs: Remove unused variable ret from sync_thread_master() Geert Uytterhoeven
2013-11-12 14:13 ` Peter Zijlstra
2013-11-12 14:21 ` David Laight
2013-11-12 14:31 ` Peter Zijlstra
2013-11-12 14:38 ` David Laight
2013-11-12 16:26 ` Oleg Nesterov
2013-11-12 14:52 ` Peter Zijlstra
2013-11-12 16:21 ` Oleg Nesterov
2013-11-12 16:56 ` oom-kill && frozen() Oleg Nesterov
2013-11-13 3:20 ` Tejun Heo [this message]
2013-11-13 17:07 ` Oleg Nesterov
2013-11-13 17:42 ` Peter Zijlstra
2013-11-13 18:15 ` Oleg Nesterov
2013-11-13 19:11 ` __refrigerator() && saved task->state Oleg Nesterov
2013-11-13 19:14 ` Peter Zijlstra
2013-11-13 19:40 ` Oleg Nesterov
2013-11-12 17:00 ` [PATCH] ipvs: Remove unused variable ret from sync_thread_master() Peter Zijlstra
2013-11-12 18:04 ` Oleg Nesterov
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