Re: Processes hang in an unkillable state

From: Oleg Nesterov
Date: Tue Apr 12 2011 - 14:28:47 EST


On 04/12, AmÃrico Wang wrote:
>
> 2011/4/12 Robert ÅwiÄcki <robert@xxxxxxxxxxx>:
> > Hi, while fuzzing Linux system calls (32bit fuzzer, 64bi linux
> > kernel), it happens after some time (10-20mins) that some processes
> > enter a state which makes them un-killable. They are either in R or D
> > state.
> >
> > # strace ps wwuax
> > ...
> > ...
> > open("/proc/450/cmdline", O_RDONLY) Â Â = 6
> > read(6, Â- Â Â Â Â Â Â hangs....
> >
> > # kill -9 450
> > # kill -9 450 (no ESRCH)
> >
> > More data in the attachment - I'll keep it in the kdb session for
> > further examination.
>
> http://marc.info/?t0260440100004
>
> Hmm, it must be stuck at
>
> lib/rwsem.c
>
> /* wait to be given the lock */
> for (;;) {
> if (!waiter.task)
> break;
> schedule();
> set_task_state(tsk, TASK_UNINTERRUPTIBLE);
> }
>
> don't know why it still can't acquire the ->mmap_sem...
>
> Cc'ing Oleg...

I seem to understand...

Please wait a bit, I need to recheck.

Oleg.

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