linux-kernel - Re: ptrace warning due to "cgroup: get rid of cgroup_freezer_frozen

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Date:   Wed, 08 May 2019 09:10:21 -0400
From:   Qian Cai <cai@....pw>
To:     Roman Gushchin <guro@...com>
Cc:     "oleg@...hat.com" <oleg@...hat.com>,
        "tj@...nel.org" <tj@...nel.org>,
        "lizefan@...wei.com" <lizefan@...wei.com>,
        "hannes@...xchg.org" <hannes@...xchg.org>,
        "cgroups@...r.kernel.org" <cgroups@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: ptrace warning due to "cgroup: get rid of
 cgroup_freezer_frozen_exit()"

On Tue, 2019-05-07 at 21:37 +0000, Roman Gushchin wrote:
> Can you, please, try if the following patch fixes the problem?

It works great.

> --
> 
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 16b72f4f14df..bf2f268f1386 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -2484,9 +2484,6 @@ bool get_signal(struct ksignal *ksig)
>                 sigdelset(&current->pending.signal, SIGKILL);
>                 recalc_sigpending();
>                 current->jobctl &= ~JOBCTL_TRAP_FREEZE;
> -               spin_unlock_irq(&sighand->siglock);
> -               if (unlikely(cgroup_task_frozen(current)))
> -                       cgroup_leave_frozen(true);
>                 goto fatal;
>         }
>  
> @@ -2608,8 +2605,10 @@ bool get_signal(struct ksignal *ksig)
>                         continue;
>                 }
>  
> -               spin_unlock_irq(&sighand->siglock);
>         fatal:
> +               spin_unlock_irq(&sighand->siglock);
> +               if (unlikely(cgroup_task_frozen(current)))
> +                       cgroup_leave_frozen(true);
>  
>                 /*
>                  * Anything else is fatal, maybe with a core dump.