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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: "Bruno Prémont" <bonbons@linux-vserver.org>
Cc: "Pádraig Brady" <P@draigBrady.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"Ingo Molnar" <mingo@elte.hu>,
	"Peter Zijlstra" <a.p.zijlstra@chello.nl>,
	"Mike Frysinger" <vapier.adi@gmail.com>,
	"KOSAKI Motohiro" <kosaki.motohiro@jp.fujitsu.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-fsdevel@vger.kernel.org,
	"Paul E. McKenney" <paul.mckenney@linaro.org>,
	"Pekka Enberg" <penberg@kernel.org>
Subject: Re: 2.6.39-rc4+: Kernel leaking memory during FS scanning, regression?
Date: Wed, 27 Apr 2011 15:05:24 -0700	[thread overview]
Message-ID: <20110427220524.GQ2135@linux.vnet.ibm.com> (raw)
In-Reply-To: <20110427213431.236c2a15@neptune.home>

On Wed, Apr 27, 2011 at 09:34:31PM +0200, Bruno Prémont wrote:
> On Wed, 27 April 2011 Pádraig Brady wrote:
> > On 27/04/11 19:41, Bruno Prémont wrote:
> > > On Wed, 27 April 2011 Bruno Prémont wrote:
> > >> On Wed, 27 Apr 2011 00:28:37 +0200 (CEST) Thomas Gleixner wrote:
> > >>> On Tue, 26 Apr 2011, Linus Torvalds wrote:
> > >>>> On Tue, Apr 26, 2011 at 10:09 AM, Bruno Prémont wrote:
> > >>>>> Just in case, /proc/$(pidof rcu_kthread)/status shows ~20k voluntary
> > >>>>> context switches and exactly one non-voluntary one.
> > >>>>>
> > >>>>> In addition when rcu_kthread has stopped doing its work
> > >>>>> `swapoff $(swapdevice)` seems to block forever (at least normal shutdown
> > >>>>> blocks on disabling swap device).
> > > 
> > > Apparently it's not swapoff but `umount -a -t tmpfs` that's getting
> > > stuck here. Manual swapoff worked.

Doesn't "umount" wait for an RCU grace period?  If so, then your hang
is just a consequence of RCU grace periods hanging, which in turn appears
to be a consequence of rcu_kthread not being allowed to run.

> > Anything to do with this?
> > http://thread.gmane.org/gmane.linux.kernel.mm/60953/
> 
> I don't think so, if it is, it is only loosely related.
> 
> From the trace you omitted to keep it's visible that it gets hit by
> non-operating RCU kthread.

Yep, makes sense!

							Thanx, Paul

> Maybe existence of RCU barrier in this trace has some relation to
> above thread but I don't see it at first glance.
> 
> [ 1714.960735] umount          D 5a000040  5668 20331  20324 0x00000000
> [ 1714.960735]  c3c99e5c 00000086 dd407900 5a000040 dd25a1a8 dd407900 dd25a120 c3c99e0c
> [ 1714.960735]  c3c99e24 c10c1be2 c14d9f20 c3c99e5c c3c8c680 c3c8c680 000000bb c3c99e24
> [ 1714.960735]  c10c0b88 dd25a120 dd407900 ddfd4b40 c3c99e4c ddfc9d20 dd402380 5a000010
> [ 1714.960735] Call Trace:
> [ 1714.960735]  [<c10c1be2>] ? check_object+0x92/0x210
> [ 1714.960735]  [<c10c0b88>] ? init_object+0x38/0x70
> [ 1714.960735]  [<c10c1be2>] ? check_object+0x92/0x210
> [ 1714.960735]  [<c13cb37d>] schedule_timeout+0x16d/0x280
> [ 1714.960735]  [<c10c0b88>] ? init_object+0x38/0x70
> [ 1714.960735]  [<c10c2122>] ? free_debug_processing+0x112/0x1f0
> [ 1714.960735]  [<c10a3791>] ? shmem_put_super+0x11/0x20
> [ 1714.960735]  [<c13cae9c>] wait_for_common+0x9c/0x150
> [ 1714.960735]  [<c102c890>] ? try_to_wake_up+0x170/0x170
> [ 1714.960735]  [<c13caff2>] wait_for_completion+0x12/0x20
> [ 1714.960735]  [<c1075ad7>] rcu_barrier_sched+0x47/0x50
>                              ^^^^^^^^^^^^^^^^^
> [ 1714.960735]  [<c104d3c0>] ? alloc_pid+0x370/0x370
> [ 1714.960735]  [<c10ce74a>] deactivate_locked_super+0x3a/0x60
> [ 1714.960735]  [<c10ce948>] deactivate_super+0x48/0x70
> [ 1714.960735]  [<c10e7427>] mntput_no_expire+0x87/0xe0
> [ 1714.960735]  [<c10e7800>] sys_umount+0x60/0x320
> [ 1714.960735]  [<c10b231a>] ? remove_vma+0x3a/0x50
> [ 1714.960735]  [<c10b3b22>] ? do_munmap+0x212/0x2f0
> [ 1714.960735]  [<c10e7ad9>] sys_oldumount+0x19/0x20
> [ 1714.960735]  [<c13cce10>] sysenter_do_call+0x12/0x26
> 
> Bruno

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  reply	other threads:[~2011-04-27 22:05 UTC|newest]

Thread overview: 88+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-24 18:21 2.6.39-rc4+: Kernel leaking memory during FS scanning, regression? Bruno Prémont
2011-04-24 21:59 ` Bruno Prémont
2011-04-25  2:42   ` KOSAKI Motohiro
2011-04-25  7:47     ` Mike Frysinger
2011-04-25  9:17       ` Bruno Prémont
2011-04-25  9:25         ` Pekka Enberg
2011-04-25 10:34           ` Bruno Prémont
2011-04-25 11:41             ` Bruno Prémont
2011-04-25 11:47               ` Pekka Enberg
2011-04-25 12:11                 ` Bruno Prémont
2011-04-25 12:14                 ` Tetsuo Handa
2011-04-25 12:21                   ` Tetsuo Handa
2011-04-25 15:22         ` Linus Torvalds
2011-04-25 16:04           ` Bruno Prémont
2011-04-25 16:31             ` Linus Torvalds
2011-04-25 17:00               ` Bruno Prémont
2011-04-25 17:10                 ` Linus Torvalds
2011-04-25 17:20                   ` Linus Torvalds
2011-04-25 18:36                   ` Bruno Prémont
2011-04-25 19:16                     ` Paul E. McKenney
2011-04-25 21:10                       ` Bruno Prémont
2011-04-25 21:26                         ` Paul E. McKenney
2011-04-25 21:30                         ` Linus Torvalds
2011-04-25 21:49                           ` Paul E. McKenney
2011-04-26  6:19                             ` Bruno Prémont
2011-04-26 11:27                               ` Paul E. McKenney
2011-04-26 16:38                                 ` Bruno Prémont
2011-04-26 17:09                                   ` Bruno Prémont
2011-04-26 17:18                                     ` Linus Torvalds
2011-04-26 22:28                                       ` Thomas Gleixner
2011-04-27  6:15                                         ` Bruno Prémont
2011-04-27 18:41                                           ` Bruno Prémont
2011-04-27 19:16                                             ` Pádraig Brady
2011-04-27 19:34                                               ` Bruno Prémont
2011-04-27 22:05                                                 ` Paul E. McKenney [this message]
2011-04-27 20:40                                             ` Bruno Prémont
2011-04-27 22:07                                               ` Paul E. McKenney
2011-04-28  6:10                                                 ` Bruno Prémont
2011-04-27 22:06                                             ` Thomas Gleixner
2011-04-27 22:27                                               ` Paul E. McKenney
2011-04-27 22:32                                                 ` Thomas Gleixner
2011-04-27 22:59                                                   ` Paul E. McKenney
2011-04-27 23:28                                                   ` Linus Torvalds
2011-04-27 23:46                                                     ` Linus Torvalds
2011-04-28  9:09                                               ` Thomas Gleixner
2011-04-28  9:17                                                 ` Sedat Dilek
2011-04-28  9:40                                                   ` Thomas Gleixner
2011-04-28 10:12                                                     ` Mike Galbraith
2011-04-28  9:45                                                 ` Sedat Dilek
2011-04-28 10:26                                                   ` Paul E. McKenney
2011-04-28 13:30                                                     ` Mike Galbraith
2011-04-28 15:28                                                       ` Sedat Dilek
2011-04-28 15:44                                                         ` Sedat Dilek
2011-04-28 15:48                                                         ` Linus Torvalds
2011-04-28 18:49                                                         ` Thomas Gleixner
2011-04-28 20:23                                                           ` Bruno Prémont
2011-04-28 20:29                                                             ` Thomas Gleixner
2011-04-28 20:44                                                               ` Bruno Prémont
2011-04-28 21:04                                                                 ` Thomas Gleixner
2011-04-28 21:51                                                                   ` john stultz
2011-04-28 22:02                                                                     ` Thomas Gleixner
2011-04-28 23:06                                                                       ` Sedat Dilek
2011-04-28 23:35                                                                         ` Sedat Dilek
2011-04-29  0:42                                                                           ` Paul E. McKenney
2011-04-29  9:34                                                                             ` Thomas Gleixner
2011-04-29  7:55                                                                       ` Sedat Dilek
2011-04-29 18:09                                                                       ` Mike Frysinger
2011-04-29 18:26                                                                         ` Thomas Gleixner
2011-04-29 19:31                                                                       ` Bruno Prémont
2011-04-29 20:10                                                                         ` Thomas Gleixner
2011-04-29 20:14                                                                           ` Bruno Prémont
2011-04-30  9:14                                                                             ` Sedat Dilek
2011-04-28 20:41                                                           ` Sedat Dilek
2011-04-28 19:22                                                         ` Mike Galbraith
2011-04-27 21:55                                         ` Paul E. McKenney
2011-04-28  6:22                                           ` Bruno Prémont
2011-04-28 10:26                                             ` Paul E. McKenney
2011-04-26 17:12                                   ` Linus Torvalds
2011-04-26 18:50                                     ` Paul E. McKenney
2011-04-26 19:17                                       ` Sedat Dilek
2011-04-27 22:02                                         ` Paul E. McKenney
2011-04-25 22:08                         ` Mike Frysinger
2011-04-25 17:29                 ` Paul E. McKenney
2011-04-25 18:13                   ` Sedat Dilek
2011-04-25 18:28                     ` Paul E. McKenney
2011-04-25 17:26               ` Paul E. McKenney
2011-04-27 10:28               ` Catalin Marinas
2011-04-25 17:51           ` Pekka Enberg

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