From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.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: __refrigerator() && saved task->state
Date: Wed, 13 Nov 2013 20:40:11 +0100 [thread overview]
Message-ID: <20131113194011.GA25590@redhat.com> (raw)
In-Reply-To: <20131113191449.GF16796@laptop.programming.kicks-ass.net>
On 11/13, Peter Zijlstra wrote:
>
> On Wed, Nov 13, 2013 at 08:11:43PM +0100, Oleg Nesterov wrote:
> > At first glance it would be better to simply kill this logic? If
> > it was called with ->state != 0, the caller is going to schedule()
> > and it probably executes the wait_event-like code, in this case
> > it would me more safe to pretend the task got a spurious wakeup?
>
> Note that in general the kernel cannot deal with spurious wakeups :/
>
> Most proper locks and wait primitives can, but there's enough open-coded
> crap out there that can not.
Oh yes, I understand.
My point is, "restore the old state" in this case looks worse simply
because you miss any wakeup in between which was going to clear that
state. And afaics only kthreads can call __refrigerator() in !RUNNING.
But let me repeat, I am almost sure I missed something else.
Oleg.
next prev parent reply other threads:[~2013-11-13 19:39 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
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 [this message]
2013-11-12 17:00 ` [PATCH] ipvs: Remove unused variable ret from sync_thread_master() Peter Zijlstra
2013-11-12 18:04 ` Oleg Nesterov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20131113194011.GA25590@redhat.com \
--to=oleg@redhat.com \
--cc=David.Laight@ACULAB.COM \
--cc=geert@linux-m68k.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=netdev@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=rientjes@google.com \
--cc=tj@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).