Messages in this thread Patch in this message | | | Date | Fri, 7 Oct 2022 15:58:03 +0200 | From | Marco Elver <> | Subject | Re: [PATCH] perf: Fix missing SIGTRAPs |
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On Fri, Oct 07, 2022 at 03:09PM +0200, Peter Zijlstra wrote: > On Fri, Oct 07, 2022 at 11:37:34AM +0200, Marco Elver wrote: > > > That worked. In addition I had to disable the ctx->task != current check > > if we're in task_work, because presumably the event might have already > > been disabled/moved?? > > Uhmmm... uhhh... damn. (wall-time was significantly longer) > > Does this help?
No unfortunately - still see:
[ 82.300827] ------------[ cut here ]------------ [ 82.301680] WARNING: CPU: 0 PID: 976 at kernel/events/core.c:6466 perf_sigtrap+0x60/0x70 [ 82.303069] Modules linked in: [ 82.303524] CPU: 0 PID: 976 Comm: missed_breakpoi Not tainted 6.0.0-rc3-00017-g1472d7e42f41-dirty #68 [ 82.304825] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-4 04/01/2014 [ 82.306204] RIP: 0010:perf_sigtrap+0x60/0x70 [ 82.306858] Code: e6 59 fa ff 48 8b 93 50 01 00 00 8b b3 d8 00 00 00 48 8b bb 30 04 00 00 e8 dd cf e8 ff 5b 5d e9 c6 59 fa ff e8 c1 59 fa ff 90 <0f> 0b 90 5b 5d e9 b6 59 fa ff 66 0f 1f 44 00 00 e8 ab 59 fa ff bf [ 82.309515] RSP: 0000:ffffa52041cbbee0 EFLAGS: 00010293 [ 82.310295] RAX: 0000000000000000 RBX: ffff902fc966a228 RCX: ffffffffa761a53f [ 82.311336] RDX: ffff902fca39c340 RSI: 0000000000000000 RDI: ffff902fc966a228 [ 82.312376] RBP: ffff902fca39c340 R08: 0000000000000001 R09: 0000000000000001 [ 82.313412] R10: 00000000ffffffff R11: 00000000ffffffff R12: ffff902fca39cbf0 [ 82.314456] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 82.315561] FS: 00007fbae0636700(0000) GS:ffff9032efc00000(0000) knlGS:0000000000000000 [ 82.316815] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 82.317708] CR2: 000000001082d318 CR3: 0000000109430002 CR4: 0000000000770ef0 [ 82.318839] DR0: 00000000008aca98 DR1: 00000000008acb38 DR2: 00000000008acae8 [ 82.319955] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 [ 82.321068] PKRU: 55555554 [ 82.321505] Call Trace: [ 82.321913] <TASK> [ 82.322267] perf_pending_task+0x7d/0xa0 [ 82.322900] task_work_run+0x73/0xc0 [ 82.323476] exit_to_user_mode_prepare+0x19d/0x1a0 [ 82.324209] irqentry_exit_to_user_mode+0x6/0x30 [ 82.324887] asm_sysvec_call_function_single+0x16/0x20 [ 82.325623] RIP: 0033:0x27d10b [ 82.326092] Code: 43 08 48 8d 04 80 48 c1 e0 04 48 8d 0d 5e f9 62 00 48 01 c8 48 83 c0 08 b9 01 00 00 00 66 90 48 8b 10 48 39 ca 75 f8 88 48 41 <f0> 48 ff 40 08 48 8b 50 10 48 39 ca 75 f7 88 48 43 f0 48 ff 40 18 [ 82.328696] RSP: 002b:00007fbae0635a60 EFLAGS: 00000246 [ 82.329470] RAX: 00000000008acaa8 RBX: 000024073fc007d0 RCX: 0000000000001add [ 82.330521] RDX: 0000000000001add RSI: 0000000000000070 RDI: 0000000000000007 [ 82.331557] RBP: 00007fbae0635a70 R08: 00007fbae0636700 R09: 00007fbae0636700 [ 82.332593] R10: 00007fbae06369d0 R11: 0000000000000202 R12: 00007fbae06369d0 [ 82.333630] R13: 00007ffe8139de16 R14: 00007fbae0636d1c R15: 00007fbae0635a80 [ 82.334713] </TASK> [ 82.335093] irq event stamp: 546455 [ 82.335657] hardirqs last enabled at (546465): [<ffffffffa7513ef6>] __up_console_sem+0x66/0x70 [ 82.337032] hardirqs last disabled at (546476): [<ffffffffa7513edb>] __up_console_sem+0x4b/0x70 [ 82.338414] softirqs last enabled at (546084): [<ffffffffa8c0034f>] __do_softirq+0x34f/0x4d5 [ 82.339769] softirqs last disabled at (546079): [<ffffffffa7493821>] __irq_exit_rcu+0xb1/0x120 [ 82.341128] ---[ end trace 0000000000000000 ]---
I now have this on top:
diff --git a/kernel/events/core.c b/kernel/events/core.c index 9319af6013f1..7de83c42d312 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2285,9 +2285,10 @@ event_sched_out(struct perf_event *event, */ local_dec(&event->ctx->nr_pending); } else { - WARN_ON_ONCE(event->pending_work); - event->pending_work = 1; - task_work_add(current, &event->pending_task, TWA_RESUME); + if (!event->pending_work) { + event->pending_work = 1; + task_work_add(current, &event->pending_task, TWA_RESUME); + } } } @@ -6466,7 +6467,8 @@ static void perf_sigtrap(struct perf_event *event) return; /* - * perf_pending_irq() can race with the task exiting. + * Both perf_pending_task() and perf_pending_irq() can race with the + * task exiting. */ if (current->flags & PF_EXITING) return; @@ -6495,8 +6497,8 @@ static void __perf_pending_irq(struct perf_event *event) if (cpu == smp_processor_id()) { if (event->pending_sigtrap) { event->pending_sigtrap = 0; - local_dec(&event->ctx->nr_pending); perf_sigtrap(event); + local_dec(&event->ctx->nr_pending); } if (event->pending_disable) { event->pending_disable = 0; @@ -6563,16 +6565,18 @@ static void perf_pending_task(struct callback_head *head) * If we 'fail' here, that's OK, it means recursion is already disabled * and we won't recurse 'further'. */ + preempt_disable_notrace(); rctx = perf_swevent_get_recursion_context(); if (event->pending_work) { event->pending_work = 0; - local_dec(&event->ctx->nr_pending); perf_sigtrap(event); + local_dec(&event->ctx->nr_pending); } if (rctx >= 0) perf_swevent_put_recursion_context(rctx); + preempt_enable_notrace(); } #ifdef CONFIG_GUEST_PERF_EVENTS I'm throwing more WARN_ON()s at it to see what's going on...
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