From: Tejun Heo <tj@kernel.org>
To: Andrea Arcangeli <aarcange@redhat.com>, Oleg Nesterov <oleg@redhat.com>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
"Rafael J. Wysocki" <rjw@suse.com>,
linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
Jiri Slaby <jirislaby@gmail.com>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] thp: reduce khugepaged freezing latency
Date: Wed, 9 Nov 2011 09:06:57 -0800 [thread overview]
Message-ID: <20111109170657.GE1260@google.com> (raw)
In-Reply-To: <20111109165925.GC1260@google.com>
Hello,
On Wed, Nov 09, 2011 at 08:59:25AM -0800, Tejun Heo wrote:
> Freezer depends on the usual "set_current_state(INTERRUPTIBLE); check
> freezing; schedule(); check freezing" construct and sends
> INTERRUPTIBLE wake up after setting freezing state. The
> synchronization hasn't been completely clear but recently been cleaned
> up, so as long as freezing condition is tested after INTERRUPTIBLE is
> set before going to sleep, the event won't go missing.
>
> Maybe we need a helper here, which would be named horribly -
> schedule_timeout_interruptible_freezable(). (cc'ing Oleg) Oleg, maybe
> we need schedule_timeout(@sleep_type) too?
Ah, crap, still waking up. Sorry about that. So, yes, there's a race
condition above. You need to set TASK_INTERRUPTIBLE before testing
freezing and use schedule_timeout() instead of
schedule_timeout_interruptible(). Was getting confused with
prepare_to_wait(). That said, why not use prepare_to_wait() instead?
Thanks.
--
tejun
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next prev parent reply other threads:[~2011-11-09 17:07 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-08 8:33 khugepaged doesn't want to freeze Jiri Slaby
2011-11-08 15:29 ` Andrea Arcangeli
2011-11-08 15:29 ` [PATCH] thp: reduce khugepaged freezing latency Andrea Arcangeli
2011-11-08 20:01 ` Srivatsa S. Bhat
2011-11-09 0:01 ` Andrea Arcangeli
2011-11-09 9:03 ` Srivatsa S. Bhat
2011-11-09 12:45 ` Srivatsa S. Bhat
2011-11-09 15:53 ` Tejun Heo
2011-11-09 16:20 ` Srivatsa S. Bhat
2011-11-09 16:52 ` Andrea Arcangeli
2011-11-09 16:59 ` Tejun Heo
2011-11-09 17:02 ` Tejun Heo
2011-11-09 17:29 ` Andrea Arcangeli
2011-11-09 18:09 ` Tejun Heo
2011-11-09 18:19 ` Andrea Arcangeli
2011-11-09 18:34 ` Tejun Heo
2011-11-09 19:40 ` Andrea Arcangeli
2011-11-11 12:20 ` Jiri Slaby
2011-11-09 17:06 ` Tejun Heo [this message]
2011-11-09 17:33 ` Andrea Arcangeli
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