From 486ff5ad49bc50315bcaf6d45f04a33ef0a45ced Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Mon, 2 Jun 2025 21:51:05 -0700 Subject: perf/core: Fix invalid wait context in ctx_sched_in() Lockdep found a bug in the event scheduling when a pinned event was failed and wakes up the threads in the ring buffer like below. It seems it should not grab a wait-queue lock under perf-context lock. Let's do it with irq_work. [ 39.913691] ============================= [ 39.914157] [ BUG: Invalid wait context ] [ 39.914623] 6.15.0-next-20250530-next-2025053 #1 Not tainted [ 39.915271] ----------------------------- [ 39.915731] repro/837 is trying to lock: [ 39.916191] ffff88801acfabd8 (&event->waitq){....}-{3:3}, at: __wake_up+0x26/0x60 [ 39.917182] other info that might help us debug this: [ 39.917761] context-{5:5} [ 39.918079] 4 locks held by repro/837: [ 39.918530] #0: ffffffff8725cd00 (rcu_read_lock){....}-{1:3}, at: __perf_event_task_sched_in+0xd1/0xbc0 [ 39.919612] #1: ffff88806ca3c6f8 (&cpuctx_lock){....}-{2:2}, at: __perf_event_task_sched_in+0x1a7/0xbc0 [ 39.920748] #2: ffff88800d91fc18 (&ctx->lock){....}-{2:2}, at: __perf_event_task_sched_in+0x1f9/0xbc0 [ 39.921819] #3: ffffffff8725cd00 (rcu_read_lock){....}-{1:3}, at: perf_event_wakeup+0x6c/0x470 Fixes: f4b07fd62d4d ("perf/core: Use POLLHUP for a pinned event in error") Closes: https://lore.kernel.org/lkml/aD2w50VDvGIH95Pf@ly-workstation Reported-by: "Lai, Yi" Signed-off-by: Namhyung Kim Signed-off-by: Peter Zijlstra (Intel) Tested-by: "Lai, Yi" Link: https://patch.msgid.link/20250603045105.1731451-1-namhyung@kernel.org --- kernel/events/core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index ac70d68217b6..4f86d22f281a 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4138,7 +4138,8 @@ static int merge_sched_in(struct perf_event *event, void *data) if (*perf_event_fasync(event)) event->pending_kill = POLL_ERR; - perf_event_wakeup(event); + event->pending_wakeup = 1; + irq_work_queue(&event->pending_irq); } else { struct perf_cpu_pmu_context *cpc = this_cpc(event->pmu_ctx->pmu); -- cgit v1.2.3