From fdf756f7127185eeffe00e918e66dfee797f3625 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 30 Sep 2022 16:39:46 +0200
Subject: [PATCH] sched: Fix more TASK_state comparisons
Boris reported hung_task splats after commit 5aec788aeb8e ("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: 5aec788aeb8e ("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>
---
kernel/hung_task.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 3a15169ba2f88..c71889f3f3fc2 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -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:
--
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