Re: 2.6.14 X spinning in the kernel

Badari Pulavarty
2005-11-15T00:52:48Z

On Mon, 2005-11-14 at 16:17 -0800, Andrew Morton wrote:
> Badari Pulavarty <pbadari@us.ibm.com> wrote:
> >
> > My 2-cpu EM64T machine started showing this problem again on 2.6.14.
> > On some reboots, X seems to spin in the kernel forever.
> >
> > sysrq-t output shows nothing.
> >
> > X R running task 0 3607 3589 3903
> > (L-TLB)
> >
> > top shows:
> > 3607 root 25 0 0 0 0 R 99.1 0.0 262:04.69 X
> >
> >
> > So, I wrote a module to do smp_call_function() on all CPUs
> > to show stacks on them. CPU0 seems to be spinning in exit_mmap().
> > I did this multiple times to collect stacks few times.
> >
> > Is this a known issue ?
>
> Nope. Maybe your vma list has a loop in it, in remove_vma()? slab
> debugging would detect that, due to the repeated
> kmem_cache_free(vm_area_cachep, vma);

I compiled the kernel with slab debug and rebooted the machine.
X seems to be spinning again. But this time, it shows completely
different routines (and seems to be switching CPUs) :(
Something weird is happening on my machine..

top:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
3600 root 25 0 0 0 0 R 99.9 0.0 8:29.18 X

CPU0:
ffffffff8053c750 0000000000000000 0000000000000000 0000000000000000
ffff81011c451000 ffffffff8053c788 ffffffff8026de8f
ffffffff8053c7a8
ffffffff80119591 ffffffff8053c7a8
Call Trace: <IRQ> <ffffffff8026de8f>{showacpu+47}
<ffffffff80119591>{smp_call_function_interrupt+81}
<ffffffff8010e968>{call_function_interrupt+132} <EOI>
<ffffffff880fc60a>{:radeon:radeon_freelist_get+122}
<ffffffff880fc69d>{:radeon:radeon_freelist_get+269}
<ffffffff880fc81a>{:radeon:radeon_cp_buffers+314}
<ffffffff880fc6e0>{:radeon:radeon_cp_buffers+0}
<ffffffff80278b32>{drm_ioctl+386} <ffffffff80199f9d>{do_ioctl
+125}
<ffffffff8019a272>{vfs_ioctl+690} <ffffffff8019a2fa>{sys_ioctl
+106}
<ffffffff8010dc9e>{system_call+126}

again,

CPU1:
ffff8100d7f2bf50 0000000000000000 0000000000000000 0000000000000000
ffff81011c451000 ffff8100d7f2bf88 ffffffff8026de8f
ffff8100d7f2bfa8
ffffffff80119591 ffff8100d7f2bfa8
Call Trace: <IRQ> <ffffffff8026de8f>{showacpu+47}
<ffffffff80119591>{smp_call_function_interrupt+81}
<ffffffff8010e968>{call_function_interrupt+132} <EOI>
<ffffffff8021363a>{__delay+10}
<ffffffff8021367a>{__const_udelay+42}
<ffffffff880fc69d>{:radeon:radeon_freelist_get+269}
<ffffffff880fc81a>{:radeon:radeon_cp_buffers+314}
<ffffffff880fc6e0>{:radeon:radeon_cp_buffers+0}
<ffffffff80278b32>{drm_ioctl+386} <ffffffff80199f9d>{do_ioctl
+125}
<ffffffff8019a272>{vfs_ioctl+690} <ffffffff8019a2fa>{sys_ioctl
+106}
<ffffffff8010dc9e>{system_call+126}

Then I tried killing it and ran into..

CPU0:
ffffffff8053c750 0000000000000000 00000000000018ff ffff81011c9a4230
ffff81011c9a4000 ffffffff8053c788 ffffffff8026de8f
ffffffff8053c7a8
ffffffff80119591 ffffffff8053c7a8
Call Trace: <IRQ> <ffffffff8026de8f>{showacpu+47}
<ffffffff80119591>{smp_call_function_interrupt+81}
<ffffffff8010e968>{call_function_interrupt+132} <EOI>
<ffffffff880fa225>{:radeon:radeon_do_wait_for_idle+117}
<ffffffff880fa236>{:radeon:radeon_do_wait_for_idle+134}
<ffffffff880fa590>{:radeon:radeon_do_cp_idle+336}
<ffffffff880fc215>{:radeon:radeon_do_release+85}
<ffffffff88104369>{:radeon:radeon_driver_pretakedown+9}
<ffffffff802783aa>{drm_takedown+74}
<ffffffff80279733>{drm_release+1267}
<ffffffff801a0d01>{destroy_inode+81}
<ffffffff801a26a1>{generic_delete_inode+337}
<ffffffff8019e9f6>{d_free+54} <ffffffff8018655a>{__fput+202}
<ffffffff80186654>{fput+20} <ffffffff80184b8e>{filp_close+110}
<ffffffff80138f62>{put_files_struct+130}
<ffffffff80139945>{do_exit+549}
<ffffffff8012f85d>{try_to_wake_up+1085}
<ffffffff80141682>{recalc_sigpending+18}
<ffffffff80141dc5>{__dequeue_signal+501}
<ffffffff8013a42d>{do_group_exit+237}
<ffffffff80143f6b>{get_signal_to_deliver+1419}
<ffffffff8010d09d>{do_signal+125}
<ffffffff803b84a9>{__up+25}
<ffffffff803bad7b>{.text.lock.kernel_lock+32}
<ffffffff80199fa5>{do_ioctl+133} <ffffffff8019a272>{vfs_ioctl
+690}
<ffffffff8010dd27>{sysret_signal+28}
<ffffffff8010d800>{do_notify_resume+48}
<ffffffff8010e00f>{ptregscall_common+103}

Thanks,
Badari