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From:   Roman Gushchin <guro@fb.com>
To:     Oleg Nesterov <oleg@redhat.com>
CC:     Bruce Ashfield <bruce.ashfield@gmail.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "tj@kernel.org" <tj@kernel.org>,
        "Richard Purdie" <richard.purdie@linuxfoundation.org>
Subject: Re: ptrace/strace and freezer oddities and v5.2+ kernels
Thread-Topic: ptrace/strace and freezer oddities and v5.2+ kernels
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Date:   Tue, 8 Oct 2019 17:27:10 +0000
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On Tue, Oct 08, 2019 at 02:36:01PM +0200, Oleg Nesterov wrote:
> On 10/08, Bruce Ashfield wrote:
> >
> > So I've been looking through the config delta's and late last night, I =
was
> > able to move the runtime back to a failed 4 minute state by adding the
> > CONFIG_PREEMPT settings that we have by default in our reference
> > kernel.

Ah, yeah, I don't have CONFIG_PREEMPT on any of my machines.
Good catch, Bruce!

>=20
> Aha... Can you try the patch below?
>=20
> Oleg.
>=20
> --- x/kernel/signal.c
> +++ x/kernel/signal.c
> @@ -2205,8 +2205,8 @@ static void ptrace_stop(int exit_code, int why, int=
 clear_code, kernel_siginfo_t
>  		 */
>  		preempt_disable();
>  		read_unlock(&tasklist_lock);
> -		preempt_enable_no_resched();
>  		cgroup_enter_frozen();
> +		preempt_enable_no_resched();
>  		freezable_schedule();
>  		cgroup_leave_frozen(true);
>  	} else {
>=20

That was fast! Thank you, Oleg!