Date:	Fri, 9 May 2008 08:31:24 +0100 (BST)
From:	Hugh Dickins <hugh@...itas.com>
To:	Theodore Tso <tytso@....EDU>
cc:	Glauber Costa <gcosta@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org
Subject: Re: Possible regression?  2.6.26-rc1: T61s failure after suspend/resume

On Thu, 8 May 2008, Theodore Tso wrote:
> On Thu, May 08, 2008 at 10:48:57PM +0100, Hugh Dickins wrote:
> > It's such a good signature, but I've failed to make progress with it.
> > Ted, please try doing the same (and check your logs for existing
> > segfault messages): let's see if you get the same number ;)
> > though I've no idea what it'd tell us.
> 
> I cant say see any such segfaults.  The only ones in my logs are
> these, and they seem to be correlated to right after a system boot:
> 
> May  5 09:35:02 closure kernel: [ 2249.245926] hald-addon-keyb[8631]: segfault at fffffffd ip b7e827bc sp bffcf1a8 error 4 in libc-2.6.1.so[b7e15000+144000]
> May  5 09:35:02 closure kernel: [ 2249.252562] hald-addon-keyb[8630]: segfault at fffffffd ip b7dcf7bc sp bf81b9d8 error 4 in libc-2.6.1.so[b7d62000+144000]

I've grown accustomed to having a hal-whatever segfault just after startup
on the T43p, and pay no attention to those: I agree yours above are in
that category, and of no relevance to our -rc1 concerns.

Yours may indeed have nothing to do with mine: the absence of (interesting)
segfault in the logs doesn't let me draw any conclusion.  If you can
get through a successful make -j3 kernel build after resume, without
X in the way, then I shall conclude yours is not mine.  But for now
I'll assume I'm on my own and plug away at it somehow.

> 
> I did find this, but it was from an attempt to do a bisect (see
> below).  In this case the system lasted half-way through the boot
> sequence (although not before the X server started) before it crashed.
> I'm beginning to think that "git bisecting" in the middle of the merge
> window just doesn't work well because some people aren't adequately
> checking to make sure the their patch series are "git bisectable" in
> terms of being bootable between arbitrary patches in their series.

I'm actually impressed by how well people generally keep to that
discipline; I see the problem as more that when there's such a
quantity of changes flowing in, the chance of one bug interfering
with the hunt for another bug goes up and up.

> So what I plan to do when I have a spare 10-15 hours is to fetch the git
> id's from patch-2.6.25-git*.id, which should hopefully represent
> somewhat more likely-to-bootable git bisection points, and try to do a
> git bisect using those points to see if the resulting kernels are a
> bit more likely to last long enough so I can test for this particular
> regression.

Good luck: doesn't sound like so much fun that I'd want to do the same!

Hugh

> 
>        	       	    	      	- Ted
> 
> P.S.  The "-numa" is due to a mistake that crept in via one of the
> patch trees (and which set -LOCALVERSION in the top-level Makefile; it
> got reverted later.)
> 
> 
> [    2.097917] 
> [    2.097919] =================================
> [    2.098059] [ INFO: inconsistent lock state ]
> [    2.098136] 2.6.25-numa-04462-g10c993a #23
> [    2.098209] ---------------------------------
> [    2.098284] inconsistent {in-hardirq-W} -> {hardirq-on-W} usage.
> [    2.098359] swapper/0 [HC0[0]:SC0[0]:HE1:SE1] takes:
> [    2.098434]  (&rq->rq_lock_key){++..}, at: [sched_clock_idle_wakeup_event+67/116] sched_clock_idle_wakeup_event+0x43/0x74
> [    2.098753] {in-hardirq-W} state was registered at:
> [    2.098833]   [__lock_acquire+1023/2834] __lock_acquire+0x3ff/0xb12
> [    2.099082]   [lock_acquire+106/144] lock_acquire+0x6a/0x90
> [    2.099329]   [_spin_lock+28/73] _spin_lock+0x1c/0x49
> [    2.099590]   [scheduler_tick+67/443] scheduler_tick+0x43/0x1bb
> [    2.099836]   [update_process_times+61/73] update_process_times+0x3d/0x49
> [    2.100083]   [tick_periodic+102/114] tick_periodic+0x66/0x72
> [    2.100327]   [tick_handle_periodic+25/106] tick_handle_periodic+0x19/0x6a
> [    2.100574]   [timer_interrupt+72/115] timer_interrupt+0x48/0x73
> [    2.100822]   [handle_IRQ_event+26/79] handle_IRQ_event+0x1a/0x4f
> [    2.101064]   [handle_level_irq+127/202] handle_level_irq+0x7f/0xca
> [    2.101316]   [do_IRQ+169/210] do_IRQ+0xa9/0xd2
> [    2.101563]   [<ffffffff>] 0xffffffff
> [    2.101806] irq event stamp: 1772935
> [    2.101883] hardirqs last  enabled at (1772935): [native_sched_clock+231/255] native_sched_clock+0xe7/0xff
> [    2.102091] hardirqs last disabled at (1772934): [native_sched_clock+109/255] native_sched_clock+0x6d/0xff
> [    2.102298] softirqs last  enabled at (1772496): [__do_softirq+249/255] __do_softirq+0xf9/0xff
> [    2.102501] softirqs last disabled at (1772491): [do_softirq+113/206] do_softirq+0x71/0xce
> [    2.102708] 
> [    2.102709] other info that might help us debug this:
> [    2.102850] no locks held by swapper/0.
> [    2.102923] 
> [    2.102924] stack backtrace:
> [    2.103067] Pid: 0, comm: swapper Not tainted 2.6.25-numa-04462-g10c993a #23
> [    2.103145]  [print_usage_bug+263/276] print_usage_bug+0x107/0x114
> [    2.103278]  [mark_lock+491/924] mark_lock+0x1eb/0x39c
> [    2.103417]  [__lock_acquire+1140/2834] __lock_acquire+0x474/0xb12
> [    2.103547]  [restore_nocheck+18/21] ? restore_nocheck+0x12/0x15
> [    2.103740]  [native_sched_clock+231/255] ? native_sched_clock+0xe7/0xff
> [    2.103929]  [lock_acquire+106/144] lock_acquire+0x6a/0x90
> [    2.104065]  [sched_clock_idle_wakeup_event+67/116] ? sched_clock_idle_wakeup_event+0x43/0x74
> [    2.104255]  [_spin_lock+28/73] _spin_lock+0x1c/0x49
> [    2.104392]  [sched_clock_idle_wakeup_event+67/116] ? sched_clock_idle_wakeup_event+0x43/0x74
> [    2.104582]  [sched_clock_idle_wakeup_event+67/116] sched_clock_idle_wakeup_event+0x43/0x74
> [    2.104715]  [<f886c3b3>] acpi_idle_enter_simple+0x19a/0x21b [processor]
> [    2.104858]  [<f886bfa5>] acpi_idle_enter_bm+0xbe/0x332 [processor]
> [    2.104999]  [cpuidle_idle_call+99/143] cpuidle_idle_call+0x63/0x8f
> [    2.105135]  [cpuidle_idle_call+0/143] ? cpuidle_idle_call+0x0/0x8f
> [    2.105330]  [cpu_idle+182/214] cpu_idle+0xb6/0xd6
> [    2.105463]  [rest_init+73/75] rest_init+0x49/0x4b
> [    2.105596]  =======================
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