From: Oleg Nesterov <oleg@redhat.com>
To: Tejun Heo <tj@kernel.org>
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: __refrigerator() && saved task->state
Date: Wed, 13 Nov 2013 20:11:43 +0100 [thread overview]
Message-ID: <20131113191143.GA24005@redhat.com> (raw)
In-Reply-To: <20131113170724.GA17739@redhat.com>
Sorry for noise, but I am totally confused.
Could you please remind why __refrigerator() saves/restores
task->state?
I can see only one reason: set_freezable() kernel threads which
check kthread_should_stop() and do try_to_freeze() by hand.
But does this save/restore actually help?
For example kauditd_thread() looks obviously racy exactly because
try_to_freeze() can return in TASK_INTERRUPTIBLE state after
wake_up(kauditd_wait) was already called, we can miss an event.
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?
(as for kauditd_thread() in particular, it looks wrong in any
case, even kthread_should_stop() check doesn't look right, it
needs kthread_freezable_should_stop() afaics).
But I guess I missed something else...
Oleg.
next prev parent reply other threads:[~2013-11-13 19:10 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 ` Oleg Nesterov [this message]
2013-11-13 19:14 ` __refrigerator() && saved task->state 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
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=20131113191143.GA24005@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).