Commit 937c6b27 authored Oct 09, 2019 by Oleg Nesterov Committed by Tejun Heo Oct 11, 2019

cgroup: freezer: call cgroup_enter_frozen() with preemption disabled in ptrace_stop()



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@gmail.com>
Fixes: 76f969e8 ("cgroup: cgroup v2 freezer")
Cc: stable@vger.kernel.org # v5.2+
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

parent 9e208aa0

kernel/signal.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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 {

Admin message