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sched: Fix more TASK_state comparisons 

Boris reported hung_task splats after commit 5aec788aeb ("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: 5aec788aeb ("sched: Fix TASK_state comparisons")
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Borislav Petkov <bp@alien8.de>
This commit is contained in:
Peter Zijlstra 2022-09-30 16:39:46 +02:00
parent 5aec788aeb
commit fdf756f712
1 changed files with 7 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
kernel/hung_task.c
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@ -95,7 +95,7 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
* Ensure the task is not frozen. * Ensure the task is not frozen.
* Also, skip vfork and any other user process that freezer should skip. * 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; return;
/* /*
@ -200,10 +200,14 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
goto unlock; goto unlock;
last_break = jiffies; 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); state = READ_ONCE(t->__state);
if ((state & TASK_UNINTERRUPTIBLE) && if ((state & TASK_UNINTERRUPTIBLE) &&
!(state & TASK_WAKEKILL)) !(state & TASK_WAKEKILL) &&
!(state & TASK_NOLOAD))
check_hung_task(t, timeout); check_hung_task(t, timeout);
} }
unlock: unlock: