From 8feb053d53194382fcfb68231296fdc220497ea6 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 19 Mar 2025 22:23:23 +0100 Subject: [PATCH] sched: Fix trace_sched_switch(.prev_state) Gabriele noted that in case of signal_pending_state(), the tracepoint sees a stale task-state. Fixes: fa2c3254d7cf ("sched/tracing: Don't re-read p->state when emitting sched_switch event") Reported-by: Gabriele Monaco Signed-off-by: Peter Zijlstra (Intel) Cc: Valentin Schneider --- kernel/sched/core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index cfaca3040b2f..042c978f7c9b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6571,12 +6571,14 @@ 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; } @@ -6713,7 +6715,7 @@ 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; } -- 2.47.3