Messages in this thread | | | Date | Mon, 19 May 2003 14:16:24 +0200 (MEST) | From | mikpe@csd ... | Subject | Re: 2.5.69+bk: oops in apmd after waking up from suspend mode |
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On Wed, 14 May 2003 11:48:13 +0200, Alex Riesen wrote: >I have an old Compaq Armada 1592DT. The thing goes automagically into >suspend mode after being forgotten for a while. And there is this button >to wake it up (the blue one, above the keyboard). > >Last time i tried to wake it up it produced the attached oops. >"Unknown key"s are probable the blue button. >After printing out the oops, the system went back into suspend. > >-alex > >Suspending devices >Suspending device c03219ac >Unable to handle kernel NULL pointer dereference at virtual address 00000090 > printing eip: >c011459f >*pde = 00000000 >Oops: 0000 [#1] >CPU: 0 >EIP: 0060:[<c011459f>] Not tainted >EFLAGS: 00010202 >EIP is at fix_processor_context+0x5f/0x100 >eax: 0000007c ebx: c5f0e000 ecx: 00000002 edx: 00000000 >esi: 00000060 edi: 00000000 ebp: c5f0ff5c esp: c5f0ff54 >ds: 007b es: 007b ss: 0068 >Process kapmd (pid: 4, threadinfo=c5f0e000 task=c5fbc640)
After receiving Alex' .config and gcc version (3.2.3), I've been able to decipher this. current->mm is NULL in the kapmd task. The call
load_LDT(¤t->mm->context); /* This does lldt */
in fix_processor_context() computes the address of context as (current->mm)+0x7c, which is 0x7c. load_LDT_nolock() dereferences 0x7c+0x14 (void *segments = pc->ldt) and the oops follows.
As to _why_ kapmd's current->mm is NULL, I don't know. It isn't when I test APM suspend in 2.5.69-bk. A lot of code dereferences current->mm without checking, so I guess current->mm==NULL is a bug.
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