From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753130AbbCWMYx (ORCPT ); Mon, 23 Mar 2015 08:24:53 -0400 Received: from terminus.zytor.com ([198.137.202.10]:41375 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752527AbbCWMYq (ORCPT ); Mon, 23 Mar 2015 08:24:46 -0400 Date: Mon, 23 Mar 2015 05:23:53 -0700 From: tip-bot for Peter Zijlstra Message-ID: Cc: acme@kernel.org, tglx@linutronix.de, paulus@samba.org, peterz@infradead.org, linux-kernel@vger.kernel.org, mingo@kernel.org, jolsa@redhat.com, hpa@zytor.com, stable@vger.kernel.org, rostedt@goodmis.org, vincent.weaver@maine.edu Reply-To: stable@vger.kernel.org, vincent.weaver@maine.edu, rostedt@goodmis.org, jolsa@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, mingo@kernel.org, acme@kernel.org, tglx@linutronix.de, paulus@samba.org, peterz@infradead.org In-Reply-To: <20150219170311.GH21418@twins.programming.kicks-ass.net> References: <20150219170311.GH21418@twins.programming.kicks-ass.net> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] perf: Fix irq_work 'tail' recursion Git-Commit-ID: d525211f9d1be8b523ec7633f080f2116f5ea536 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: d525211f9d1be8b523ec7633f080f2116f5ea536 Gitweb: http://git.kernel.org/tip/d525211f9d1be8b523ec7633f080f2116f5ea536 Author: Peter Zijlstra AuthorDate: Thu, 19 Feb 2015 18:03:11 +0100 Committer: Ingo Molnar CommitDate: Mon, 23 Mar 2015 10:46:32 +0100 perf: Fix irq_work 'tail' recursion Vince reported a watchdog lockup like: [] perf_tp_event+0xc4/0x210 [] perf_trace_lock+0x12a/0x160 [] lock_release+0x130/0x260 [] _raw_spin_unlock_irqrestore+0x24/0x40 [] do_send_sig_info+0x5d/0x80 [] send_sigio_to_task+0x12f/0x1a0 [] send_sigio+0xae/0x100 [] kill_fasync+0x97/0xf0 [] perf_event_wakeup+0xd4/0xf0 [] perf_pending_event+0x33/0x60 [] irq_work_run_list+0x4c/0x80 [] irq_work_run+0x18/0x40 [] smp_trace_irq_work_interrupt+0x3f/0xc0 [] trace_irq_work_interrupt+0x6d/0x80 Which is caused by an irq_work generating new irq_work and therefore not allowing forward progress. This happens because processing the perf irq_work triggers another perf event (tracepoint stuff) which in turn generates an irq_work ad infinitum. Avoid this by raising the recursion counter in the irq_work -- which effectively disables all software events (including tracepoints) from actually triggering again. Reported-by: Vince Weaver Tested-by: Vince Weaver Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Paul Mackerras Cc: Steven Rostedt Cc: Link: http://lkml.kernel.org/r/20150219170311.GH21418@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- kernel/events/core.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/kernel/events/core.c b/kernel/events/core.c index 453ef61..2fabc06 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4574,6 +4574,13 @@ static void perf_pending_event(struct irq_work *entry) { struct perf_event *event = container_of(entry, struct perf_event, pending); + int rctx; + + rctx = perf_swevent_get_recursion_context(); + /* + * If we 'fail' here, that's OK, it means recursion is already disabled + * and we won't recurse 'further'. + */ if (event->pending_disable) { event->pending_disable = 0; @@ -4584,6 +4591,9 @@ static void perf_pending_event(struct irq_work *entry) event->pending_wakeup = 0; perf_event_wakeup(event); } + + if (rctx >= 0) + perf_swevent_put_recursion_context(rctx); } /*