From: Pavel Machek <pavel@ucw.cz>
To: Nigel Cunningham <ncunningham@crca.org.au>
Cc: Linux-PM <linux-pm@lists.linux-foundation.org>
Subject: Re: Freezer: Don't count threads waiting for frozen filesystems.
Date: Tue, 28 Oct 2008 18:49:54 +0100 [thread overview]
Message-ID: <20081028174953.GA1434@ucw.cz> (raw)
In-Reply-To: <1224886068.6478.21.camel@nigel-laptop>
Hi!
> While working on freezing fuse filesystems, I found that if a filesystem
> is frozen when we try to freeze processes, freezing can fail because
> threads are waiting in vfs_check_frozen for the filesystem to be thawed.
> We should thus not count such threads.
>
> The check will be safe if a filesystem is thawed while we're freezing
> processes because filesystem thaws are only invoked from userspace. Any
> waiting processes will be woken and frozen prior to us completing the
> freezing of userspace (the caller invoking the filesystem thaw will be
> freezing) or - in the worst case - together with kernel threads.
In the worst case we have a problem.
Userspace and kernel threads *need* to be frozen separately...
(Otherwise its a race, and if you freeze kjournald first, user process
becomes unfreezeable and freezing fails.)
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2008-10-28 17:49 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-24 22:07 Freezer: Don't count threads waiting for frozen filesystems Nigel Cunningham
2008-10-26 20:01 ` Rafael J. Wysocki
[not found] ` <200810262101.08822.rjw@sisk.pl>
2008-10-27 11:12 ` Miklos Szeredi
[not found] ` <E1KuQ1J-0002Vw-9Q@pomaz-ex.szeredi.hu>
2008-10-27 11:20 ` Nigel Cunningham
[not found] ` <1225106427.26724.5.camel@nigel-laptop>
2008-10-27 11:37 ` Rafael J. Wysocki
2008-10-27 11:37 ` Miklos Szeredi
[not found] ` <200810271237.40049.rjw@sisk.pl>
2008-10-27 11:40 ` Nigel Cunningham
[not found] ` <1225107607.26724.9.camel@nigel-laptop>
2008-10-27 12:38 ` Miklos Szeredi
[not found] ` <E1KuRN4-0002gS-Hq@pomaz-ex.szeredi.hu>
2008-10-27 20:59 ` Nigel Cunningham
[not found] ` <1225141168.26724.23.camel@nigel-laptop>
2008-10-27 21:09 ` Miklos Szeredi
[not found] ` <E1KuZKt-0003jl-2N@pomaz-ex.szeredi.hu>
2008-10-27 22:13 ` Nigel Cunningham
[not found] ` <1225145607.26724.54.camel@nigel-laptop>
2008-10-28 20:25 ` Miklos Szeredi
[not found] ` <E1Kuv87-00064p-Lk@pomaz-ex.szeredi.hu>
2008-10-28 21:29 ` Nigel Cunningham
[not found] ` <1225229399.9661.13.camel@nigel-laptop>
2008-10-28 21:51 ` Miklos Szeredi
[not found] ` <E1KuwTn-0006EQ-8J@pomaz-ex.szeredi.hu>
2008-10-28 22:00 ` Rafael J. Wysocki
[not found] ` <200810282300.31164.rjw@sisk.pl>
2008-10-28 22:02 ` Miklos Szeredi
[not found] ` <E1Kuwe3-0006Gc-LF@pomaz-ex.szeredi.hu>
2008-10-28 22:21 ` Rafael J. Wysocki
[not found] ` <200810282321.59041.rjw@sisk.pl>
2008-10-28 23:21 ` Miklos Szeredi
[not found] ` <E1Kuxsg-0006PR-Tr@pomaz-ex.szeredi.hu>
2008-10-28 23:59 ` Rafael J. Wysocki
[not found] ` <200810290059.38411.rjw@sisk.pl>
2008-10-29 8:10 ` Miklos Szeredi
2008-10-28 22:03 ` Nigel Cunningham
2008-10-28 23:04 ` Nigel Cunningham
[not found] ` <1225235054.9661.37.camel@nigel-laptop>
2008-10-28 23:12 ` Miklos Szeredi
[not found] ` <E1Kuxk4-0006NT-Ie@pomaz-ex.szeredi.hu>
2008-10-28 23:17 ` Nigel Cunningham
[not found] ` <1225235860.9661.42.camel@nigel-laptop>
2008-10-28 23:24 ` Miklos Szeredi
[not found] ` <E1KuxvH-0006Q0-Dy@pomaz-ex.szeredi.hu>
2008-10-28 23:41 ` Nigel Cunningham
[not found] ` <1225237298.9661.55.camel@nigel-laptop>
2008-10-28 23:45 ` Miklos Szeredi
[not found] ` <E1KuyFq-0006Sc-PC@pomaz-ex.szeredi.hu>
2008-10-28 23:50 ` Miklos Szeredi
2008-10-28 23:54 ` Nigel Cunningham
[not found] ` <E1KuyKw-0006UP-EK@pomaz-ex.szeredi.hu>
2008-10-28 23:58 ` Nigel Cunningham
2008-10-28 17:49 ` Pavel Machek [this message]
[not found] <E1Kv688-0007Kp-SN@pomaz-ex.szeredi.hu>
2008-10-29 13:51 ` Alan Stern
[not found] <Pine.LNX.4.44L0.0810290944240.2515-100000@iolanthe.rowland.org>
2008-10-29 14:50 ` Miklos Szeredi
[not found] <E1KvCN9-00081i-KF@pomaz-ex.szeredi.hu>
2008-10-29 15:28 ` Alan Stern
[not found] <Pine.LNX.4.44L0.0810291122220.2189-100000@iolanthe.rowland.org>
2008-10-29 15:50 ` Miklos Szeredi
2008-10-29 16:10 ` Miklos Szeredi
[not found] <E1KvDJp-00088f-2b@pomaz-ex.szeredi.hu>
2008-10-29 16:17 ` Alan Stern
[not found] <E1KvDcp-0008B7-SR@pomaz-ex.szeredi.hu>
2008-10-29 20:37 ` Alan Stern
[not found] ` <Pine.LNX.4.44L0.0810291627040.3986-100000@iolanthe.rowland.org>
2008-10-29 21:11 ` Rafael J. Wysocki
[not found] ` <200810292211.49021.rjw@sisk.pl>
2008-10-29 21:45 ` Nigel Cunningham
[not found] ` <1225316715.18786.1.camel@nigel-laptop>
2008-10-29 22:07 ` Rafael J. Wysocki
2008-10-29 23:48 ` Miklos Szeredi
[not found] ` <200810292307.26945.rjw@sisk.pl>
2008-10-29 23:53 ` Miklos Szeredi
[not found] ` <E1KvKql-0000dC-3M@pomaz-ex.szeredi.hu>
2008-11-09 13:44 ` Pavel Machek
[not found] ` <E1KvKm8-0000cP-6f@pomaz-ex.szeredi.hu>
2008-10-30 13:04 ` Nigel Cunningham
2008-10-29 23:43 ` Miklos Szeredi
2008-10-29 23:56 ` Matthew Garrett
[not found] <E1KvKgv-0000bf-RS@pomaz-ex.szeredi.hu>
2008-10-30 13:54 ` Alan Stern
[not found] <1225371842.8576.6.camel@nigel-laptop>
2008-10-30 13:56 ` Alan Stern
2008-10-30 21:44 ` Nigel Cunningham
[not found] ` <1225403060.6574.10.camel@nigel-laptop>
2008-10-31 8:49 ` Miklos Szeredi
[not found] ` <E1Kvpgo-00045l-GU@pomaz-ex.szeredi.hu>
[not found] ` <1225444253.6574.21.camel@nigel-laptop>
[not found] ` <E1Kvq72-00049W-O1@pomaz-ex.szeredi.hu>
2008-10-31 11:28 ` Nigel Cunningham
[not found] ` <1225452484.6574.35.camel@nigel-laptop>
2008-10-31 12:44 ` Miklos Szeredi
[not found] ` <E1KvtMn-0004YD-00@pomaz-ex.szeredi.hu>
2008-10-31 21:11 ` Nigel Cunningham
[not found] <Pine.LNX.4.44L0.0810300943001.2401-100000@iolanthe.rowland.org>
2008-10-30 14:39 ` Miklos Szeredi
[not found] ` <E1KvYgR-0002Cx-AZ@pomaz-ex.szeredi.hu>
2008-10-30 17:07 ` Alan Stern
2008-10-30 20:17 ` Rafael J. Wysocki
2008-11-15 16:58 ` Pavel Machek
[not found] <Pine.LNX.4.44L0.0810301301540.2513-100000@iolanthe.rowland.org>
2008-10-30 17:43 ` Miklos Szeredi
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