[CRIU] hang when restoring container with zombies

[Pavel Emelyanov]

On 07/17/2015 06:36 PM, Tycho Andersen wrote:
> Hi all,
> 
> I'm experiencing a hang when restoring a process with zombies; the
> zombies exit, but the parent process (in this case the container's
> init) isn't getting the SIGCHLD, so it just gets stuck waiting for
> zombies_inprogress. The parent process' /proc/pid/status is below, and
> it doesn't seem to be blocking SIGCHLD and there are no pending
> signals. I stuck a printf in the sigchld_handler in the restorer blob,
> and it does get called for sid helpers, but not for the zombie
> processes.
> 
> Does anyone have any ideas about what's going wrong? I have no idea
> why the signal would be blocked.

Maybe it's not blocked but merged with another (previous) sigchild?

> Tycho
> 
> 
> Name: systemd
> State:  S (sleeping)
> Tgid: 5773
> Ngid: 0
> Pid:  5773
> PPid: 5770
> TracerPid:  5771
> Uid:  0 0 0 0
> Gid:  0 0 0 0
> FDSize: 1024
> Groups: 0 
> VmPeak:    46440 kB
> VmSize:    34536 kB
> VmLck:         0 kB
> VmPin:         0 kB
> VmHWM:      3476 kB
> VmRSS:       924 kB
> VmData:      740 kB
> VmStk:       136 kB
> VmExe:      1260 kB
> VmLib:      3468 kB
> VmPTE:        88 kB
> VmSwap:        0 kB
> Threads:  1
> SigQ: 6/7723
> SigPnd: 0000000000000000
> ShdPnd: 0000000000000000
> SigBlk: fffffffe7ffafeff
> SigIgn: 0000000000001000
> SigCgt: 00000001800104ec
> CapInh: 0000000000000000
> CapPrm: 0000003fffffffff
> CapEff: 0000003fffffffff
> CapBnd: 0000003fffffffff
> Seccomp:  0
> Cpus_allowed: f
> Cpus_allowed_list:  0-3
> Mems_allowed: 00000000,00000001
> Mems_allowed_list:  0
> voluntary_ctxt_switches:  48
> nonvoluntary_ctxt_switches: 11
> 
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