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

[Steven Rostedt]

On Sat, 2010-10-23 at 22:02 +0200, Ingo Molnar wrote:
> * Jason Baron <jbaron@xxxxxxxxxx> wrote:
> 
> > > 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)
> > 
> > if possible, can you post that .config?
> 
> I just reproduced it again with tip-1128a72 - config and full bootlog attached.
> 
> The crash picture tends to vary - sometimes it crashes in fork, sometimes in the 
> timer interrupt. Here's the current one:
> 
> [   15.384483] Running tests on trace events:
> [   15.388580] Testing event kfree_skb: 
> [   15.392381] BUG: unable to handle kernel NULL pointer dereference at (null)
> [   15.395408] IP: [<(null)>] (null)

Interesting, the jump was to NULL. I'm thinking it hit a trace point and
jumped to a NULL address. I guess there's some strange race here. Is a
cache flush missing somewhere. I'll look more into this on Monday.

-- Steve


> [   15.395408] *pde = 00000000 
> [   15.395408] Oops: 0000 [#1] SMP 
> [   15.395408] last sysfs file: 
> [   15.395408] 
> [   15.395408] Pid: 2, comm: kthreadd Not tainted 2.6.36-tip-03573-g1128a72-dirty #51926 A8N-E/System Product Name
> [   15.395408] EIP: 0060:[<00000000>] EFLAGS: 00010086 CPU: 0
> [   15.395408] EIP is at 0x0
> [   15.395408] EAX: c1049bb5 EBX: 00000286 ECX: 00000000 EDX: 00000000
> [   15.395408] ESI: 00000000 EDI: f5cd96e0 EBP: 00000063 ESP: f6449f24
> [   15.395408]  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
> [   15.395408] Process kthreadd (pid: 2, ti=f6448000 task=f64443d0 task.ti=f6448000)
> [   15.395408] Stack:
> [   15.395408]  c104d4e6 00800711 00000000 00000000 00000000 00000001 f6a09b00 f64443d0
> [   15.395408]  c188a238 c1dffb00 c1f1f200 00000000 c1049c53 b3420a74 00800711 c1061a4b
> [   15.395408]  f6449fc0 f6449f7c c102ea40 00000000 00000000 00000000 00000000 00000000
> [   15.395408] Call Trace:
> [   15.395408]  [<c104d4e6>] ? do_fork+0x205/0x2aa
> [   15.395408]  [<c1049c53>] ? dequeue_task+0x97/0xa6
> [   15.395408]  [<c1061a4b>] ? kthread+0x0/0x68
> [   15.395408]  [<c102ea40>] ? kernel_thread+0x77/0x7f
> [   15.395408]  [<c1061a4b>] ? kthread+0x0/0x68
> [   15.395408]  [<c10299c0>] ? kernel_thread_helper+0x0/0x10
> [   15.395408]  [<c1061b40>] ? kthreadd+0x8d/0xbf
> [   15.395408]  [<c1061ab3>] ? kthreadd+0x0/0xbf
> [   15.395408]  [<c10299c6>] ? kernel_thread_helper+0x6/0x10
> [   15.395408] Code:  Bad EIP value.
> [   15.395408] EIP: [<00000000>] 0x0 SS:ESP 0068:f6449f24
> [   15.395408] CR2: 0000000000000000
> [   15.395408] ---[ end trace 105d75af79111d22 ]---
> 
> (One possibility would be kernel text corruption perhaps.)
> 
> Thanks,
> 
> 	Ingo


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