Messages in this thread | | | Date | Thu, 1 Jun 2006 15:02:50 -0700 | From | Andrew Morton <> | Subject | Re: 2.6.17-rc5-mm1 |
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Chuck Ebbert <76306.1226@compuserve.com> wrote: > > In-Reply-To: <447DD4D3.3060205@free.fr> > > On Wed, 31 May 2006 19:39:31 +0200, Laurent Riffard wrote: > > > pktcdvd: writer pktcdvd0 mapped to hdc > > BUG: unable to handle kernel NULL pointer dereference at virtual address 00000084 > > printing eip: > > c01118f1 > > *pde = 00000000 > > Oops: 0000 [#1] > > last sysfs file: /block/pktcdvd0/removable > > Modules linked in: pktcdvd lp parport_pc parport snd_pcm_oss snd_mixer_oss snd_ens1371 gameport snd_rawmidi snd_seq_device snd_ac97_codec snd_ac97_bus snd_pcm snd_timer snd_page_alloc snd soundcore af_packet floppy ide_cd cdrom loop aes dm_crypt nl > > CPU: 0 > > EIP: 0060:[<c01118f1>] Not tainted VLI > > EFLAGS: 00010006 (2.6.17-rc5-mm1 #11) > > EIP is at do_page_fault+0xb4/0x5bc > > eax: d6750084 ebx: d6750000 ecx: 0000007b edx: 00000000 > > esi: d6758000 edi: c011183d ebp: d675007c esp: d6750044 > > ds: 007b es: 007b ss: 0068 > > Process (pid: 0, threadinfo=d674f000 task=d657c000) > > Stack: 00000000 d6750084 00000000 00000049 00000084 00000000 00001e2e 02001120 > > 00000027 00000022 00000055 d6750000 d6758000 c011183d d67500f0 c010340d > > d6750000 0000007b 00000000 d6758000 c011183d d67500f0 d67500f8 0000007b > > Call Trace: > > [<c010340d>] error_code+0x39/0x40 > > Code: 00 00 c0 81 0f 84 12 02 00 00 e9 1c 05 00 00 8b 45 cc f7 40 30 00 02 02 00 74 06 e8 68 af 01 00 fb f7 43 14 ff ff ff ef 8b 55 d0 <8b> b2 84 00 00 00 0f 85 e5 01 00 00 85 f6 0f 84 dd 01 00 00 8d > > EIP: [<c01118f1>] do_page_fault+0xb4/0x5bc SS:ESP 0068:d6750044 > > arch/i386/mm/fault.c::do_page_fault(): > > 12: f7 40 30 00 02 02 00 testl $0x20200,0x30(%eax) > 19: 74 06 je 21 <_EIP+0x21> > if (regs->eflags & (X86_EFLAGS_IF|VM_MASK)) > > 1b: e8 68 af 01 00 call 1af88 <_EIP+0x1af88> > 20: fb sti > local_irq_enable(); > > local_irq_enable() should only be doing an sti; your code has an extra > function call. Do you have any extra patches applied?
This is all the lockdep stuff - it adds instrumentation to local_irq_foo().
> 21: f7 43 14 ff ff ff ef testl $0xefffffff,0x14(%ebx) > if (in_atomic()... > > 28: 8b 55 d0 mov 0xffffffd0(%ebp),%edx > Get tsk from local storage and put it in edx. > > 00000000 <_EIP>: > 0: 8b b2 84 00 00 00 mov 0x84(%edx),%esi <===== > mm = tsk->mm; > > tsk was zero here, implying that current was 0 when the page fault happened. > > > 6: 0f 85 e5 01 00 00 jne 1f1 <_EIP+0x1f1> > c: 85 f6 test %esi,%esi > e: 0f 84 dd 01 00 00 je 1f1 <_EIP+0x1f1> > > > > Andrew, should we add debug code to the fault handler to test for current == 0?
`current == 0' implies a scrogged thread_info. I'm not sure what debugging we could usefully add to the pagefault handler to detect that. Apart from getting a good backtrace. Which the x86_64 guys have broken.
Laurent, please disable CONFIG_STACK_UNWIND and try again - that way we should be able to see whereabouts the thread-info got corrupted.
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