Re: [PATCH] cgroup: freezer: call cgroup_enter_frozen() with preemption disabled in ptrace_stop()
From: Tejun Heo
Date: Fri Oct 11 2019 - 12:52:20 EST
On Wed, Oct 09, 2019 at 05:02:30PM +0200, Oleg Nesterov wrote:
> ptrace_stop() does preempt_enable_no_resched() to avoid the preemption,
> but after that cgroup_enter_frozen() does spin_lock/unlock and this adds
> another preemption point.
> Reported-and-tested-by: Bruce Ashfield <bruce.ashfield@xxxxxxxxx>
> Fixes: 76f969e8948d ("cgroup: cgroup v2 freezer")
> Cc: stable@xxxxxxxxxxxxxxx # v5.2+
> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Applied to cgroup/for-5.4-fixes.