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From: Pavel Machek <pavel@ucw.cz>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Andrew Morton <akpm@osdl.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Oleg Nesterov <oleg@tv-sign.ru>,
	Aneesh Kumar <aneesh.kumar@gmail.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Srivatsa Vaddagiri <vatsa@in.ibm.com>,
	Gautham R Shenoy <ego@in.ibm.com>
Subject: Re: [PATCH -mm 2/7] Freezer: Close theoretical race between refrigerator and thaw_tasks
Date: Thu, 1 Mar 2007 16:39:08 +0000	[thread overview]
Message-ID: <20070301163907.GA4710@ucw.cz> (raw)
In-Reply-To: <200703011608.13758.rjw@sisk.pl>

On Thu 2007-03-01 16:08:12, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@sisk.pl>
> 
> If the freezing of tasks fails and a task is preempted in refrigerator() before
> calling frozen_process(), then thaw_tasks() may run before this task is frozen.
> In that case the task will freeze and no one will thaw it.
> 
> To fix this race we can call freezing(current) in refrigerator() along with
> frozen_process(current) under the task_lock() which also should be taken in
> the error path of try_to_freeze_tasks() as well as in thaw_process().  Moreover,
> if thaw_process() additionally clears TIF_FREEZE for tasks that are not frozen,
> we can be sure that all tasks are thawed and there are no pending "freeze"
> requests after thaw_tasks() has run.
> 
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

ack.
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

  reply	other threads:[~2007-03-01 16:39 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-26  7:00 [PATCH -mm 0/6] Freezer changes Rafael J. Wysocki
2007-02-26  7:02 ` [PATCH -mm 1/6] Freezer: Read PF_BORROWED_MM in a nonracy way Rafael J. Wysocki
2007-02-26  7:05 ` [PATCH -mm 2/6] Freezer: Fix memory ordering in refrigerator Rafael J. Wysocki
2007-02-26 11:32   ` Oleg Nesterov
2007-02-26  7:06 ` [PATCH -mm 3/6] Freezer: Close theoretical race between refrigerator and thaw_tasks Rafael J. Wysocki
2007-02-26  7:08 ` [PATCH -mm 4/6] Freezer: Remove PF_NOFREEZE from rcutorture thread Rafael J. Wysocki
2007-02-26  7:11 ` [PATCH -mm 5/6] Freezer: Remove PF_NOFREEZE from bluetooth threads Rafael J. Wysocki
2007-02-26  7:13 ` [PATCH -mm 6/6] Freezer: Add try_to_freeze calls to all kernel threads Rafael J. Wysocki
2007-03-01 15:05 ` [PATCH -mm 0/7] Freezer changes (take 2) Rafael J. Wysocki
2007-03-01 15:06   ` [PATCH -mm 1/7] Freezer: Read PF_BORROWED_MM in a nonracy way Rafael J. Wysocki
2007-03-01 15:08   ` [PATCH -mm 2/7] Freezer: Close theoretical race between refrigerator and thaw_tasks Rafael J. Wysocki
2007-03-01 16:39     ` Pavel Machek [this message]
2007-03-01 15:09   ` [PATCH -mm 3/7] Freezer: Remove PF_NOFREEZE from rcutorture thread Rafael J. Wysocki
2007-03-01 19:38     ` Anton Blanchard
2007-03-01 19:54       ` Rafael J. Wysocki
2007-03-02 21:35         ` Paul E. McKenney
2007-03-02 22:16           ` Anton Blanchard
2007-03-02 23:33           ` Oleg Nesterov
2007-03-03  0:58             ` Paul E. McKenney
2007-03-03 17:32               ` Oleg Nesterov
2007-03-04  4:34                 ` Srivatsa Vaddagiri
2007-03-11 17:49                 ` [PATCH] kthread_should_stop_check_freeze (was: Re: [PATCH -mm 3/7] Freezer: Remove PF_NOFREEZE from rcutorture thread) Rafael J. Wysocki
2007-03-12  4:38                   ` Paul E. McKenney
2007-03-12  8:14                     ` Pavel Machek
2007-03-12 11:19                       ` Rafael J. Wysocki
2007-03-12 12:23                         ` Oleg Nesterov
2007-03-12 13:24                           ` [PATCH] kthread_should_stop_check_freeze Cedric Le Goater
2007-03-12 18:25                             ` Rafael J. Wysocki
2007-03-12 22:39                         ` [PATCH] kthread_should_stop_check_freeze (was: Re: [PATCH -mm 3/7] Freezer: Remove PF_NOFREEZE from rcutorture thread) Pavel Machek
2007-03-12 22:45                           ` Anton Blanchard
2007-03-13  3:14                             ` Srivatsa Vaddagiri
2007-03-13  9:16                               ` Christoph Hellwig
2007-03-13  9:58                                 ` Srivatsa Vaddagiri
2007-03-13 10:20                                   ` Christoph Hellwig
2007-03-20 18:08                             ` Pavel Machek
2007-03-13  0:58                           ` Paul E. McKenney
2007-03-20 18:10                             ` Pavel Machek
2007-03-13  5:27                   ` Gautham R Shenoy
2007-03-13  5:42                     ` Srivatsa Vaddagiri
2007-03-03  1:03             ` [PATCH -mm 3/7] Freezer: Remove PF_NOFREEZE from rcutorture thread Rafael J. Wysocki
2007-03-02  6:57     ` Gautham R Shenoy
2007-03-02 21:46       ` Paul E. McKenney
2007-03-01 15:10   ` [PATCH -mm 4/7] Freezer: Remove PF_NOFREEZE from bluetooth threads Rafael J. Wysocki
2007-03-01 15:12   ` [PATCH -mm 5/7] Freezer: Add try_to_freeze calls to all kernel threads Rafael J. Wysocki
2007-03-01 15:15   ` [PATCH -mm 6/7] Freezer: Fix vfork problem Rafael J. Wysocki
2007-03-01 15:17   ` [PATCH -mm 7/7] Freezer: Take kernel_execve into consideration Rafael J. Wysocki

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