Re: [Kernel Bug] INFO: task hung in cgroup_drain_dying

[Michal Koutný]

On Wed, Jun 10, 2026 at 03:11:41PM +0800, Longxing Li <coregee2000@xxxxxxxxx> wrote:
> sorry for not containing full information in last email. the config[1]
> and report[2] are as follows. CONFIG_PROVE_LOCKING is not enabled in
> our config.

Thanks.

> INFO: task systemd:1 blocked for more than 143 seconds.
>       Not tainted 7.0.6 #1
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:systemd         state:D stack:20616 pid:1     tgid:1     ppid:0
>    task_flags:0x400100 flags:0x00080001
> Call Trace:
>  <TASK>
>  context_switch kernel/sched/core.c:5298 [inline]
>  __schedule+0x1006/0x5f00 kernel/sched/core.c:6911
>  __schedule_loop kernel/sched/core.c:6993 [inline]
>  schedule+0xe7/0x3a0 kernel/sched/core.c:7008
>  cgroup_drain_dying+0x1ed/0x360 kernel/cgroup/cgroup.c:6294
>  cgroup_rmdir+0x38/0x300 kernel/cgroup/cgroup.c:6309
>  kernfs_iop_rmdir+0x10a/0x180 fs/kernfs/dir.c:1311
>  vfs_rmdir fs/namei.c:5344 [inline]
>  vfs_rmdir+0x340/0x860 fs/namei.c:5317
>  filename_rmdir+0x3be/0x510 fs/namei.c:5399
>  __do_sys_rmdir fs/namei.c:5422 [inline]
>  __se_sys_rmdir fs/namei.c:5419 [inline]
>  __x64_sys_rmdir+0x47/0x90 fs/namei.c:5419
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x11b/0xf80 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f

Hm, hm, this kinds fits 93618edf75383 ("cgroup: Defer css percpu_ref
kill on rmdir until cgroup is depopulated") 
which got into stable 7.0.9.
Can you reproduce even with that (or newer) kernel?

Michal

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