Hello,
The following program creates processes deadlocked in snd_seq_pool_done:
https://gist.githubusercontent.com/dvyukov/97efc9cb6d63b1b2c7b737b82cc8b0d6/...
After few seconds I get:
# ps afxu | grep a.out root 8660 2.0 0.0 0 0 pts/0 Zl 16:27 0:00 [a.out] <defunct>
# kill -9 8660
# cat /proc/8660/status Name: a.out State: Z (zombie) Tgid: 8660 Ngid: 0 Pid: 8660 PPid: 1 TracerPid: 0 Uid: 0 0 0 0 Gid: 0 0 0 0 FDSize: 0 Groups: 0 NStgid: 8660 NSpid: 8660 NSpgid: 8660 NSsid: 2971 Threads: 2 SigQ: 1/3304 SigPnd: 0000000000000000 ShdPnd: 0000000000000100 SigBlk: 0000000000000000 SigIgn: 0000000180000000 SigCgt: 0000000000000440 CapInh: 0000000000000000 CapPrm: 0000003fffffffff CapEff: 0000003fffffffff CapBnd: 0000003fffffffff CapAmb: 0000000000000000 NoNewPrivs: 0 Seccomp: 0 Cpus_allowed: f Cpus_allowed_list: 0-3 Mems_allowed: 00000000,00000001 Mems_allowed_list: 0 voluntary_ctxt_switches: 12 nonvoluntary_ctxt_switches: 0
# cat /proc/8660/task/*/stack [<ffffffff835406db>] snd_seq_pool_done+0x31b/0x620 sound/core/seq/seq_memory.c:436 [<ffffffff8353a11e>] snd_seq_ioctl_set_client_pool+0x1ae/0x600 sound/core/seq/seq_clientmgr.c:1836 [<ffffffff835382ba>] snd_seq_ioctl+0x2da/0x4d0 sound/core/seq/seq_clientmgr.c:2130 [<ffffffff81aced2f>] vfs_ioctl fs/ioctl.c:45 [inline] [<ffffffff81aced2f>] do_vfs_ioctl+0x1bf/0x1790 fs/ioctl.c:685 [<ffffffff81ad038f>] SYSC_ioctl fs/ioctl.c:700 [inline] [<ffffffff81ad038f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691 [<ffffffff8457dc41>] entry_SYSCALL_64_fastpath+0x1f/0xc2