Re: kernel panics with uvideo, savecores and coredumps

[Christoph Egger <Christoph_Egger%gmx.de@localhost>]

Christoph Egger wrote:
> Christoph Egger wrote:
>> Hi,
>>
>> I can reproduce kernel panics when two
>> programs (mplayer and ekiga) *simultanously*
>> try to access my webcam.
>>
>>
>> In ddb I do "call dumpsys" or "sync" and reboot
>> blindly (I'm in X when the panic happens).
>>
>> On reboot, savecore prints things like
>>
>> panic: kmem_poison_check  x != y  (where x and y are numbers)

More details on this panic:

panic: kmem_poison_check: 0xffff80004e98e1a0: 0x50 != 0x1a

db{1}> bt
breakpoint() at netbsd:breakpoint+0x5
panic() at netbsd:pani+0x260
kmem_poison_check() at netbsd:kmem_poison_check+0x82
kmem_alloc() at netbsd:kmem_alloc+0x58
amap_alloc() at netbsd:amap_alloc+0x111
amap_copy() at netbsd:amap_copy+0x34a
uvM_fault_internal() at netbsd:uvm_fault_internal+0xe53
trap() at netbsd:trap+0x817
trap (number 1191182377)
0x3830303220332e31:
db{1}> mach cpu 0
using cpu 0
db{1}> bt
x86_stihlt() at netbsd:x86_stihlt+0x6
idle_loop() at netbsd:idle_loop+0x18e
db{1}>

>> or
>>
>> panic: extent_alloc_subregion: bad size
>>
>> To debug a crash dump I following the instructions from:
>> http://www.netbsd.org/docs/kernel/#debugging_a_kernel_crash_dump
>>
>> But I always get backtraces from ddb instead the one from the panic.
>>
>> Using ps ax -M netbsd.x.core results in a segfault
>> in kvm_getproc2() in libkvm.
> 
> The crash happens in lib/libkvm/kvm_proc.c , line 566:
> 
> kp2p->p_forw = kl[0].l_forw;
> 
> The kl pointer is NULL. kvm_getlwps() in line 560
> returns NULL and there's no NULL-pointer check.
> nlwps passed to kvm_getlwps() is 1.
> 
> 
> Christoph