Re: [PATCH][GIT PULL] tracing: Fix compile issue fortrace_sched_wakeup.c

[Ingo Molnar]

* Jason Baron <jbaron@xxxxxxxxxx> wrote:

> On Thu, Oct 21, 2010 at 01:09:25PM +0200, Ingo Molnar wrote:
> > * Ingo Molnar <mingo@xxxxxxx> wrote:
> > 
> > > 
> > > * Jason Baron <jbaron@xxxxxxxxxx> wrote:
> > > 
> > > > [...] Do we always fail after "Testing all events:" is printed? [...]
> > > 
> > > Yes, in all cases i checked. Sometimes it's an oops.
> > 
> > Such as this one:
> > 
> > [    6.724449] Testing event kmalloc_node: OK
> > [    6.744459] Testing event kmem_cache_alloc_node: 
> > [    6.749111] BUG: unable to handle kernel paging request at ffffffff
> > [    6.752000] IP: [<f6425f7c>] 0xf6425f7c
> > [    6.752000] *pde = 01384067 *pte = 00000000 
> > [    6.752000] Oops: 0002 [#1] PREEMPT SMP 
> > [    6.752000] last sysfs file: 
> > [    6.752000] Modules linked in:
> > [    6.752000] 
> > [    6.752000] Pid: 2, comm: kthreadd Not tainted 2.6.36-rc8-tip+ #50831 /
> > [    6.752000] EIP: 0060:[<f6425f7c>] EFLAGS: 00010282 CPU: 0
> > [    6.752000] EIP is at 0xf6425f7c
> > [    6.752000] EAX: ffffffff EBX: c1021c4f ECX: 00000001 EDX: 00000000
> > [    6.752000] ESI: f6425f7c EDI: fffffff4 EBP: f640c000 ESP: f6425ee4
> > [    6.752000]  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
> > [    6.752000] Process kthreadd (pid: 2, ti=f6424000 task=f640c000 task.ti=f6424000)
> > [    6.752000] Stack:
> > [    6.752000]  c1021c4f f640c02c 00800711 00000000 00000000 00000000 f6425f7c f6809880
> > [    6.752000] <0> f6425f7c 00000000 00000000 f6425f7c c1022a54 00000000 00000000 00000000
> > [    6.752000] <0> 00000000 00800711 00000000 00000000 00000000 c101d94a f6809880 c131f3a0
> > [    6.752000] Call Trace:
> > [    6.752000]  [<c1021c4f>] ? copy_process+0xa1/0xd6d
> > [    6.752000]  [<c1022a54>] ? do_fork+0x139/0x2ca
> > [    6.752000]  [<c101d94a>] ? dequeue_task+0xb9/0xc8
> > [    6.752000]  [<c1245597>] ? schedule+0x821/0x84b
> > [    6.752000]  [<c1038079>] ? kthread+0x0/0x68
> > [    6.752000]  [<c1007930>] ? kernel_thread+0x77/0x7f
> > [    6.752000]  [<c1038079>] ? kthread+0x0/0x68
> > [    6.752000]  [<c1002cbc>] ? kernel_thread_helper+0x0/0x10
> > [    6.752000]  [<c1038172>] ? kthreadd+0x91/0xc7
> > [    6.752000]  [<c10380e1>] ? kthreadd+0x0/0xc7
> > [    6.752000]  [<c1002cc2>] ? kernel_thread_helper+0x6/0x10
> > [    6.752000] Code: 98 80 f6 00 c0 40 f6 a9 37 61 f9 11 07 80 00 79 80 03 c1 c0 5f 42 f6 7c 5f 42 f6 30 79 00 c1 00 00 00 00 00 00 00 00 00 00 00 00 <00> 00 00 00 00 00 00 00 00 00 00 00 79 80 03 c1 70 3f 42 f6 00 
> > [    6.752000] EIP: [<f6425f7c>] 0xf6425f7c SS:ESP 0068:f6425ee4
> > [    6.752000] CR2: 00000000ffffffff
> > [    6.752000] ---[ end trace 6000cf675d3eddec ]---
> > 
> > (captured two days ago)
> > 
> > Full bootlog is attached below.
> > 
> > Thanks,
> > 
> > 	Ingo
> > 
> 
> Hi,
> 
> this looks potentially like a separate issue from the 'hang' one - I'm wondering 
> if this was re-produced with the same .config as the 'hang' case? I haven't been 
> able to hit this one yet....

Not the same config, and it's very spurious - i.e. a slightly different -tip version 
with the same config will boot fine. (this suggests some race)

Something very much not good with the fundamental mechanics of jump labels i'm 
afraid. It might be corrupting some memory here, or have some window of 
vulnerability in which an IRQ hits (or so) we will crash.

Thanks,

	Ingo
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