Messages in this thread | | | Date | Mon, 23 Nov 2009 09:36:23 +0100 | From | Nick Piggin <> | Subject | Re: Zombie process when ptracing |
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On Fri, Nov 20, 2009 at 02:29:30AM +0100, Oleg Nesterov wrote: > Hi, > > On 11/19, Nick Piggin wrote: > > > > Running recent git kernel, I have a process stuck in Z state > > > > bash ? 0000000000000000 0 3188 3187 0x00000000 > > ffff88012e24fec8 0000000000000046 0000000000000000 0000000000000012 > > ffff88012e24fec8 ffff88012e24e000 ffff88012e24ffd8 ffff88012e24e000 > > 000000000000efc8 ffff88012e24e000 ffff88012ea82090 ffff88012ff78640 > > Call Trace: > > [<ffffffff8124baee>] ? proc_clear_tty+0x5e/0x70 > > [<ffffffff810587a8>] ? exit_ptrace+0xb8/0x140 > > [<ffffffff8105126a>] do_exit+0x58a/0x7c0 > > [<ffffffff810514dd>] do_group_exit+0x3d/0xb0 > > [<ffffffff81051562>] sys_exit_group+0x12/0x20 > > [<ffffffff8100b3eb>] system_call_fastpath+0x16/0x1b > > > > This was after stracing a few test programs. > > > > It also seems to have lost job control (^C) at the same time. > > This can happen if the tracer (strace) itself hangs, zombies > should go away once the tracer is killed. Or its ->real_parent > is stopped or hangs... > > (I assume you didn't strace /sbin/init)
No, I straced something else, and all straces seemed to be killed but bash remained. I was running a script that in turn launched another process, so I ran it via strace -ff bash ./script.sh
> But, > > > Hmm, and the kernel just paniced with an nmi lockup while I was > > trying to get more info. > > this probably means we have a kernel bug ;)
Hmm sorry that seemed like it _may_ have been an unrelated issue (with the ssh connection).
> If you see a zombie again, could you look at its /ptoc/pid/status?
OK, any other hints if I see it again?
> And of course, which programs did you trace and how? It would be > great if we can reproduce the problem.
At this stage I have not reproduced it, and I can't share the program which was being straced. If it does happen again and I cannot distil a simple test case, I will ask permission to distribute it.
Thanks, Nick
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