Commit fdf756f7 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

sched: Fix more TASK_state comparisons 



Boris reported hung_task splats after commit 5aec788a ("sched: Fix
TASK_state comparisons"). Upon closer consideration of that change it
doesn't only exclude TASK_KILLABLE, but also TASK_IDLE.

Update the comment to reflect this fact and add an additional
TASK_NOLOAD test to exclude them.

Additionally, remove the TASK_FREEZABLE early exit from
check_hung_task(), a freezable task is not a frozen task.

Fixes: 5aec788a ("sched: Fix TASK_state comparisons")
Reported-by: default avatarBorislav Petkov <bp@alien8.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: default avatarBorislav Petkov <bp@alien8.de>
parent 5aec788a

kernel/hung_task.c

+7 −3
Original line number Diff line number Diff line
@@ -95,7 +95,7 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout) 
	 * Ensure the task is not frozen.

	 * Also, skip vfork and any other user process that freezer should skip.

	 */

	if (unlikely(READ_ONCE(t->__state) & (TASK_FREEZABLE | TASK_FROZEN)))

	if (unlikely(READ_ONCE(t->__state) & TASK_FROZEN))

		return;



	/*
@@ -200,10 +200,14 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) 
				goto unlock;

			last_break = jiffies;

		}

		/* skip the TASK_KILLABLE tasks -- these can be killed */

		/*

		 * skip the TASK_KILLABLE tasks -- these can be killed

		 * skip the TASK_IDLE tasks -- those are genuinely idle

		 */

		state = READ_ONCE(t->__state);

		if ((state & TASK_UNINTERRUPTIBLE) &&

		    !(state & TASK_WAKEKILL))

		    !(state & TASK_WAKEKILL) &&

		    !(state & TASK_NOLOAD))

			check_hung_task(t, timeout);

	}

 unlock: