Messages in this thread | | | Date | Thu, 17 Aug 2006 03:06:28 +0159 | From | Jiri Slaby <> | Subject | Re: workqueue lockdep bug. |
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Andrew Morton wrote: > On Mon, 14 Aug 2006 14:33:19 -0400 > Dave Jones <davej@redhat.com> wrote: > >> Andrew, >> I merged the workqueue changes from -mm into the Fedora-devel kernel to >> kill off those billion cpufreq lockdep warnings. The bug has now mutated >> into this: >> >> (Trimmed version of log from >> https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=202223) >> > > I don't get it.
Let me extend the output a little bit:
clock = mutex_lock(cpu_add_remove_lock) wqlock = mutex_lock(workqueue_mutex) slock = mutex_lock(cpu_chain.rwsem) similar for cunlock, wqunlock, sunlock.
The number after colon is linenumber, where the mutex_XXX lies. Prints are _after_ mutex_lock and _before_ mutex_unlock calls.
So here it comes:
[ 30.947289] clock: 268 [ 30.947340] Disabling non-boot CPUs ... [ 30.947392] slock: 334 [ 30.964622] wqlock: 689 [ 30.964659] sunlock: 336
Isn't this strange for validator (lock1-lock2-unlock1 + (below)lock1-unlock2-unlock1)?
[ 30.966762] Breaking affinity for irq 0 [ 30.968116] CPU 1 is now offline [ 30.968155] lockdep: not fixing up alternatives. [ 30.968200] [ 30.968201] ======================================================= [ 30.968269] [ INFO: possible circular locking dependency detected ] [ 30.968307] 2.6.18-rc4-mm1-bug #11 [ 30.968342] -------------------------------------------------------
>> > Breaking affinity for irq 185 >> > Breaking affinity for irq 193 >> > Breaking affinity for irq 209 >> > CPU 1 is now offline >> > lockdep: not fixing up alternatives. >> > >> > ======================================================= >> > [ INFO: possible circular locking dependency detected ] >> > 2.6.17-1.2548.fc6 #1 >> > ------------------------------------------------------- >> > pm-hibernate/4335 is trying to acquire lock: >> > ((cpu_chain).rwsem){..--}, at: [<c0430fa4>] >> blocking_notifier_call_chain+0x11/0x2d >> > >> > but task is already holding lock: >> > (workqueue_mutex){--..}, at: [<c0612820>] mutex_lock+0x21/0x24 >> > >> > which lock already depends on the new lock. >> > >> > >> > the existing dependency chain (in reverse order) is: >> > >> > -> #1 (workqueue_mutex){--..}: >> > [<c043c08e>] lock_acquire+0x4b/0x6d >> > [<c06126b1>] __mutex_lock_slowpath+0xbc/0x20a >> > [<c0612820>] mutex_lock+0x21/0x24 >> > [<c0433c25>] workqueue_cpu_callback+0xfd/0x1ee >> > [<c0614ef5>] notifier_call_chain+0x20/0x31 >> > [<c0430fb0>] blocking_notifier_call_chain+0x1d/0x2d >> > [<c043f4c5>] _cpu_down+0x47/0x1c4 >> > [<c043f805>] disable_nonboot_cpus+0x9b/0x11a >> > [<c0445b32>] prepare_processes+0xe/0x41 >> > [<c0445d87>] pm_suspend_disk+0x9/0xf3 >> > [<c0444e12>] enter_state+0x54/0x1b7 >> > [<c0444ffb>] state_store+0x86/0x9c >> > [<c04a9f88>] subsys_attr_store+0x20/0x25 >> > [<c04aa08c>] sysfs_write_file+0xab/0xd1 >> > [<c04732cb>] vfs_write+0xab/0x157 >> > [<c0473910>] sys_write+0x3b/0x60 >> > [<c0403faf>] syscall_call+0x7/0xb > > cpu_add_remove_lock -> cpu_chain.rwsem -> workqueue_mutex > >> > -> #0 ((cpu_chain).rwsem){..--}: >> > [<c043c08e>] lock_acquire+0x4b/0x6d >> > [<c04390a0>] down_read+0x2d/0x40 >> > [<c0430fa4>] blocking_notifier_call_chain+0x11/0x2d >> > [<c043f5aa>] _cpu_down+0x12c/0x1c4 >> > [<c043f805>] disable_nonboot_cpus+0x9b/0x11a >> > [<c0445b32>] prepare_processes+0xe/0x41 >> > [<c0445d87>] pm_suspend_disk+0x9/0xf3 >> > [<c0444e12>] enter_state+0x54/0x1b7 >> > [<c0444ffb>] state_store+0x86/0x9c >> > [<c04a9f88>] subsys_attr_store+0x20/0x25 >> > [<c04aa08c>] sysfs_write_file+0xab/0xd1 >> > [<c04732cb>] vfs_write+0xab/0x157 >> > [<c0473910>] sys_write+0x3b/0x60 >> > [<c0403faf>] syscall_call+0x7/0xb > > cpu_add_remove_lock -> cpu_chain.rwsem > >> > other info that might help us debug this: >> > >> > 2 locks held by pm-hibernate/4335: >> > #0: (cpu_add_remove_lock){--..}, at: [<c0612820>] >> mutex_lock+0x21/0x24 >> > #1: (workqueue_mutex){--..}, at: [<c0612820>] mutex_lock+0x21/0x24 >> > >> > stack backtrace: >> > [<c04051ee>] show_trace_log_lvl+0x58/0x159 >> > [<c04057ea>] show_trace+0xd/0x10 >> > [<c0405903>] dump_stack+0x19/0x1b >> > [<c043b176>] print_circular_bug_tail+0x59/0x64 >> > [<c043b98e>] __lock_acquire+0x80d/0x99c >> > [<c043c08e>] lock_acquire+0x4b/0x6d >> > [<c04390a0>] down_read+0x2d/0x40 >> > [<c0430fa4>] blocking_notifier_call_chain+0x11/0x2d >> > [<c043f5aa>] _cpu_down+0x12c/0x1c4 >> > [<c043f805>] disable_nonboot_cpus+0x9b/0x11a >> > [<c0445b32>] prepare_processes+0xe/0x41 >> > [<c0445d87>] pm_suspend_disk+0x9/0xf3 >> > [<c0444e12>] enter_state+0x54/0x1b7 >> > [<c0444ffb>] state_store+0x86/0x9c >> > [<c04a9f88>] subsys_attr_store+0x20/0x25 >> > [<c04aa08c>] sysfs_write_file+0xab/0xd1 >> > [<c04732cb>] vfs_write+0xab/0x157 >> > [<c0473910>] sys_write+0x3b/0x60 >> > [<c0403faf>] syscall_call+0x7/0xb
[ 30.981176] [<c0170514>] sys_write+0x47/0x6e [ 30.981249] [<c01031fb>] syscall_call+0x7/0xb [ 30.981322] ======================= [ 30.981378] slock: 334
The one, that failed.
[ 30.981882] wqunlock: 702 [ 30.981939] sunlock: 336 [ 30.981996] CPU1 is down [ 30.982036] cunlock: 309 [ 30.982075] Stopping tasks: ============ [ 31.149008] ==================|
> cpu_add_remove_lock -> cpu_chain.rwsem > > I don't see anywhere where this process took workqueue_mutex.
Hope this helps?
regards, -- http://www.fi.muni.cz/~xslaby/ Jiri Slaby faculty of informatics, masaryk university, brno, cz e-mail: jirislaby gmail com, gpg pubkey fingerprint: B674 9967 0407 CE62 ACC8 22A0 32CC 55C3 39D4 7A7E
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