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sched: Fix trace_sched_switch(.prev_state)

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[ Upstream commit 8feb053d53194382fcfb68231296fdc220497ea6 ]

Gabriele noted that in case of signal_pending_state(), the tracepoint
sees a stale task-state.

Fixes: fa2c3254d7 ("sched/tracing: Don't re-read p->state when emitting sched_switch event")
Reported-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Peter Zijlstra
2025-03-19 22:23:23 +01:00
committed by Greg Kroah-Hartman
parent e8d0d9ae99
commit 623074162b
1 changed files with 4 additions and 2 deletions
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6
kernel/sched/core.c
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@@ -6517,12 +6517,14 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
* Otherwise marks the task's __state as RUNNING
*/
static bool try_to_block_task(struct rq *rq, struct task_struct *p,
unsigned long task_state)
unsigned long *task_state_p)
{
unsigned long task_state = *task_state_p;
int flags = DEQUEUE_NOCLOCK;
if (signal_pending_state(task_state, p)) {
WRITE_ONCE(p->__state, TASK_RUNNING);
*task_state_p = TASK_RUNNING;
return false;
}
@@ -6656,7 +6658,7 @@ static void __sched notrace __schedule(int sched_mode)
goto picked;
}
} else if (!preempt && prev_state) {
try_to_block_task(rq, prev, prev_state);
try_to_block_task(rq, prev, &prev_state);
switch_count = &prev->nvcsw;
}