Messages in this thread | | | Date | Tue, 3 Jun 2008 09:22:28 -0300 | From | "Kevin Winchester" <> | Subject | Re: linux-next: WARNING: at kernel/lockdep.c:2680 check_flags+0x98/0x151() |
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On Tue, Jun 3, 2008 at 5:53 AM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote: > On Mon, 2008-06-02 at 20:47 -0300, Kevin Winchester wrote: >> In next-20080530 and next-20080602 (and possibly earlier - I can't >> remember the linux-next tree before that I tried) I get the following: >> >> [ 12.885153] ------------[ cut here ]------------ >> [ 12.885203] WARNING: at kernel/lockdep.c:2680 check_flags+0x98/0x151() >> [ 12.885248] Pid: 4, comm: watchdog/0 Not tainted >> 2.6.26-rc4-next-20080602 #13 >> [ 12.885292] >> [ 12.885293] Call Trace: >> [ 12.885364] [<ffffffff8022bbd5>] warn_on_slowpath+0x58/0x8a >> [ 12.885410] [<ffffffff804c9cfe>] ? _spin_unlock_irqrestore+0x51/0x6d >> [ 12.885455] [<ffffffff8032ff41>] ? debug_locks_off+0x9/0x3c >> [ 12.885498] [<ffffffff802582dd>] ? ftrace_record_ip+0x1fa/0x272 >> [ 12.885542] [<ffffffff8025278a>] ? watchdog+0xc5/0x1ff >> [ 12.885584] [<ffffffff8020b2c0>] ? mcount_call+0x5/0x35 >> [ 12.885627] [<ffffffff8025278a>] ? watchdog+0xc5/0x1ff >> [ 12.885668] [<ffffffff80247c80>] check_flags+0x98/0x151 >> [ 12.885710] [<ffffffff8024ae72>] lock_acquire+0x4a/0xa9 >> [ 12.885753] [<ffffffff8025278a>] ? watchdog+0xc5/0x1ff >> [ 12.885795] [<ffffffff802526c5>] ? watchdog+0x0/0x1ff >> [ 12.885837] [<ffffffff804c98da>] _read_lock+0x37/0x43 >> [ 12.885879] [<ffffffff8025278a>] watchdog+0xc5/0x1ff >> [ 12.885921] [<ffffffff802526c5>] ? watchdog+0x0/0x1ff >> [ 12.885963] [<ffffffff8023e48b>] kthread+0x4e/0x7b >> [ 12.886005] [<ffffffff8020bf18>] child_rip+0xa/0x12 >> [ 12.886046] [<ffffffff80227d8f>] ? finish_task_switch+0x57/0x92 >> [ 12.886090] [<ffffffff804c9d55>] ? _spin_unlock_irq+0x3b/0x57 >> [ 12.886133] [<ffffffff8020bad3>] ? restore_args+0x0/0x30 >> [ 12.886137] [<ffffffff8023e43d>] ? kthread+0x0/0x7b >> [ 12.886137] [<ffffffff8020bf0e>] ? child_rip+0x0/0x12 >> [ 12.886137] >> [ 12.886137] ---[ end trace 60e7f098a6913839 ]--- >> [ 12.886137] possible reason: unannotated irqs-on. >> [ 12.886137] irq event stamp: 20 >> [ 12.886137] hardirqs last enabled at (19): [<ffffffff80249cc3>] >> trace_hardirqs_on+0xd/0xf >> [ 12.886137] hardirqs last disabled at (20): [<ffffffff80248565>] >> trace_hardirqs_off+0xd/0xf >> [ 12.886137] softirqs last enabled at (0): [<ffffffff80229fef>] >> copy_process+0x2da/0x109e >> [ 12.886137] softirqs last disabled at (0): [<0000000000000000>] 0x0 >> >> Do I understand this correctly that something enabled irqs in a way that >> got around lockdep? I assume the problem is not in watchdog, just that >> the watchdog was the next thing to run that interacted with irqs and >> thus lockdep picked up the situation then? >> >> Is there additional debugging I can do, given some instructions? If the >> cause is readily apparent to anyone, could they let me know (for my own >> interest) why it is apparent so that I can investigate things like this >> further next time? > > > You are correct - someone did sti but failed to call > trace_hardirqs_on(). Frequently its possible to isolate the code from > knowing the last recorded event: > > [ 12.886137] irq event stamp: 20 > [ 12.886137] hardirqs last disabled at (20): [<ffffffff80248565>] trace_hardirqs_off+0xd/0xf > > However your compilation seems to have lost the caller IP: > > void trace_hardirqs_off(void) > { > trace_hardirqs_off_caller(CALLER_ADDR0); > } > EXPORT_SYMBOL(trace_hardirqs_off); > > So that is of little help here. (Not sure how that happened, nor how you > could fix that - perhaps turn on some debugging knobs like build with > debug info etc..) >
Could this be related to CONFIG_CC_OPTIMIZE_INLINING (or whatever it is called now)? I am pretty sure I have that enabled. I will check the rest of my config this evening to see if there is anything else I can turn on/off to help.
> >> This is completely reproducible on every boot - should I try to bisect it? > > That is a possibility yes - if you can find the offending patch it > should be relatively straight forward to find the offending sti. >
Sure - I can try it this evening. Also, is calling sti the only way this could have happened? And is linux-next broken out into a single patch? I wouldn't expect there to be too many calls to sti, so a grep in the patch file might be quicker than bisection.
Thanks,
-- Kevin Winchester
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