Messages in this thread Patch in this message | | | Date | Thu, 27 Aug 2009 12:08:46 +0200 | From | Oleg Nesterov <> | Subject | Re: mmotm 2009-08-24-16-24 uploaded |
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On 08/27, KAMEZAWA Hiroyuki wrote: > > On Thu, 27 Aug 2009 11:34:41 +0200 > Oleg Nesterov <oleg@redhat.com> wrote: > > > On 08/27, KAMEZAWA Hiroyuki wrote: > > > > > > On Thu, 27 Aug 2009 14:44:53 +0900 > > > KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > > > > > > > > > > > In the newest mmotom, my S14nfslock hangs up. (x86-64/Fedora10) > > > > > > > > On Mon, 24 Aug 2009 16:28:30 -0700 > > > > akpm@linux-foundation.org wrote: > > > > > > > > > ptrace-__ptrace_detach-do-__wake_up_parent-if-we-reap-the-tracee.patch > > > > > do_wait-wakeup-optimization-shift-security_task_wait-from-eligible_child-to-wait_consider_task.patch > > > > > > > > bisected. following 2 patches for filtering SIGCHLD cause hang (for my environ). > > > > > > > > > do_wait-wakeup-optimization-change-__wake_up_parent-to-use-filtered-wakeup.patch > > > > > do_wait-wakeup-optimization-change-__wake_up_parent-to-use-filtered-wakeup-selinux_bprm_committed_creds-use-__wake_up_parent.patch > > > > Confused. Which patch causes the hang? They should be applied in reverse order, > > > > do_wait-wakeup-optimization-change-__wake_up_parent-to-use-filtered-wakeup-selinux_bprm_committed_creds-use-__wake_up_parent.patch > > do_wait-wakeup-optimization-change-__wake_up_parent-to-use-filtered-wakeup.patch > > > > > removed S14nfslockd from rc5.d and check it by strace > > > == > > > 2712] fstat(6, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0 > > > [pid 2712] mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fc6f263c000 > > > [pid 2712] dup(6) = 7 > > > [pid 2712] write(6, "2712\n"..., 5) = 5 > > > [pid 2712] close(6) = 0 > > > [pid 2712] munmap(0x7fc6f263c000, 4096) = 0 > > > [pid 2712] clone(Process 2713 attached > > > child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7fc6f2625780) = 2713 > > > [pid 2712] wait4(2713, Process 2712 suspended > > > <unfinished ...> > > > == > > > When process 2713 exits, process 2712 don't wake up. > > > > Hmm, very strange. How can I reproduce? > > > Sorry, I don't know. > > But exited process's, but not caught, p->exit_signal was -1. (confirmed by printk) > (details in another mail)
Ah, I didn't notice "Process 2713 attached" above, I guess you did strace -f.
The child was reaped by strace, because
> Name: rpc.statd > State: S (sleeping) > ... > SigIgn: 0000000000011000
indeed, SIGCHLD is ignored.
OK, I seem to understand what happens. Could you try the patch below?
Oleg.
--- a/kernel/exit.c +++ b/kernel/exit.c @@ -1564,9 +1564,6 @@ static int child_wait_callback(wait_queu child_wait); struct task_struct *p = key; - if (!eligible_child(wo, p)) - return 0; - if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) return 0;
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