Messages in this thread | | | Date | Thu, 24 Sep 2009 18:13:19 +0200 | From | Michal Schmidt <> | Subject | Re: BUG: sleeping function called from invalid context at kernel/mutex.c:280 |
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Dne Thu, 24 Sep 2009 17:29:52 +0200 Martin Schwidefsky napsal(a): > On Thu, 24 Sep 2009 15:33:19 +0200 > Michal Schmidt <mschmidt@redhat.com> wrote: > > I've just noticed the same in the latest git. > > sysdev_resume() runs with IRQs disabled, but clocksource_resume() > > uses a mutex. Hmm, in 2.6.30 it used to be spinlock. This was > > changed to mutex by: > > > > commit 75c5158f70c065b9704b924503d96e8297838f79 > > Author: Martin Schwidefsky <schwidefsky@de.ibm.com> > > Date: Fri Aug 14 15:47:30 2009 +0200 > > > > timekeeping: Update clocksource with stop_machine > > > > update_wall_time calls change_clocksource HZ times per second to > > check if a new clock source is available. In close to 100% of > > all calls there is no new clock. Replace the tick based check by an > > update done with stop_machine. > > Hmm, the spinlock to mutex conversion is necessary to make it possible > to use stop_machine to install the new clocksource. At the same time > clocksource_resume is called early in the resume cycle with interrupts > disabled and may not take a mutex. Question is: does it have to? There > shouldn't be any processes running that can change the list of > installed clocksources. Can you test if this patch fixes the problem? > > -- > Subject: [PATCH] clocksource: resume clocksource without taking the > clocksource mutex > > From: Martin Schwidefsky <schwidefsky@de.ibm.com> > > git commit 75c5158f70c065b9 converted the clocksource spinlock to a > mutex. This causes the following BUG: > > BUG: sleeping function called from invalid context at > kernel/mutex.c:280 in_atomic(): 0, irqs_disabled(): 1, pid: 2473, > name: pm-suspend 2 locks held by pm-suspend/2473: > #0: (&buffer->mutex){......}, at: [<ffffffff8115ab13>] > sysfs_write_file+0x3c/0x137 > #1: (pm_mutex){......}, at: [<ffffffff810865b5>] > enter_state+0x39/0x130 Pid: 2473, comm: pm-suspend Not tainted 2.6.31 > #1 Call Trace: > [<ffffffff810792f0>] ? __debug_show_held_locks+0x22/0x24 > [<ffffffff8104a2ef>] __might_sleep+0x107/0x10b > [<ffffffff8141fca9>] mutex_lock_nested+0x25/0x43 > [<ffffffff81073537>] clocksource_resume+0x1c/0x60 > [<ffffffff81072902>] timekeeping_resume+0x1e/0x1c8 > [<ffffffff812aee62>] __sysdev_resume+0x25/0xcf > [<ffffffff812aef79>] sysdev_resume+0x6d/0xae > [<ffffffff810864f8>] suspend_devices_and_enter+0x12b/0x1af > [<ffffffff8108665b>] enter_state+0xdf/0x130 > [<ffffffff81085dc3>] state_store+0xb6/0xd3 > [<ffffffff81204c73>] kobj_attr_store+0x17/0x19 > [<ffffffff8115abd2>] sysfs_write_file+0xfb/0x137 > [<ffffffff811057d2>] vfs_write+0xae/0x10b > [<ffffffff81208392>] ? __up_read+0x1a/0x7f > [<ffffffff811058ef>] sys_write+0x4a/0x6e > [<ffffffff81011b82>] system_call_fastpath+0x16/0x1b > > clocksource_resume is called early in the resume process, there > is only one cpu, no processes are running and the interrupts are > disabled. It is therefore possible to resume the clocksources > without taking the clocksource mutex. > > Reported-by: Xiaotian Feng <xtfeng@gmail.com> > Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Yes, this fixes the problem. Tested-by: Michal Schmidt <mschmidt@redhat.com>
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