[CRIU] hang when restoring container with zombies

[Tycho Andersen]

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.

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