From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12C5FC433F5 for ; Thu, 9 Sep 2021 06:10:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DCCB261158 for ; Thu, 9 Sep 2021 06:10:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352200AbhIIGL7 (ORCPT ); Thu, 9 Sep 2021 02:11:59 -0400 Received: from out30-132.freemail.mail.aliyun.com ([115.124.30.132]:38754 "EHLO out30-132.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231438AbhIIGL5 (ORCPT ); Thu, 9 Sep 2021 02:11:57 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R141e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04394;MF=yun.wang@linux.alibaba.com;NM=1;PH=DS;RN=19;SR=0;TI=SMTPD_---0UnlsHEw_1631167844; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0UnlsHEw_1631167844) by smtp.aliyun-inc.com(127.0.0.1); Thu, 09 Sep 2021 14:10:46 +0800 Subject: Re: [RFC PATCH] perf: fix panic by mark recursion inside perf_log_throttle From: =?UTF-8?B?546L6LSH?= To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , "open list:PERFORMANCE EVENTS SUBSYSTEM" , "open list:PERFORMANCE EVENTS SUBSYSTEM" , "open list:BPF (Safe dynamic programs and tools)" , "open list:BPF (Safe dynamic programs and tools)" References: Message-ID: <83859259-7597-460f-bc9b-487e4efa8ab7@linux.alibaba.com> Date: Thu, 9 Sep 2021 14:10:44 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Reported-by: Abaci On 2021/9/9 上午11:13, 王贇 wrote: > When running with ftrace function enabled, we observed panic > as below: > > traps: PANIC: double fault, error_code: 0x0 > [snip] > RIP: 0010:perf_swevent_get_recursion_context+0x0/0x70 > [snip] > Call Trace: > > perf_trace_buf_alloc+0x26/0xd0 > perf_ftrace_function_call+0x18f/0x2e0 > kernelmode_fixup_or_oops+0x5/0x120 > __bad_area_nosemaphore+0x1b8/0x280 > do_user_addr_fault+0x410/0x920 > exc_page_fault+0x92/0x300 > asm_exc_page_fault+0x1e/0x30 > RIP: 0010:__get_user_nocheck_8+0x6/0x13 > perf_callchain_user+0x266/0x2f0 > get_perf_callchain+0x194/0x210 > perf_callchain+0xa3/0xc0 > perf_prepare_sample+0xa5/0xa60 > perf_event_output_forward+0x7b/0x1b0 > __perf_event_overflow+0x67/0x120 > perf_swevent_overflow+0xcb/0x110 > perf_swevent_event+0xb0/0xf0 > perf_tp_event+0x292/0x410 > perf_trace_run_bpf_submit+0x87/0xc0 > perf_trace_lock_acquire+0x12b/0x170 > lock_acquire+0x1bf/0x2e0 > perf_output_begin+0x70/0x4b0 > perf_log_throttle+0xe2/0x1a0 > perf_event_nmi_handler+0x30/0x50 > nmi_handle+0xba/0x2a0 > default_do_nmi+0x45/0xf0 > exc_nmi+0x155/0x170 > end_repeat_nmi+0x16/0x55 > > According to the trace we know the story is like this, the NMI > triggered perf IRQ throttling and call perf_log_throttle(), > which triggered the swevent overflow, and the overflow process > do perf_callchain_user() which triggered a user PF, and the PF > process triggered perf ftrace which finally lead into a suspected > stack overflow. > > This patch marking the context as recursion during perf_log_throttle() > , so no more swevent during the process and no more panic. > > Signed-off-by: Michael Wang > --- > kernel/events/core.c | 14 +++++++++----- > 1 file changed, 9 insertions(+), 5 deletions(-) > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 744e872..6063443 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -8716,6 +8716,7 @@ static void perf_log_throttle(struct perf_event *event, int enable) > struct perf_output_handle handle; > struct perf_sample_data sample; > int ret; > + int rctx; > > struct { > struct perf_event_header header; > @@ -8738,14 +8739,17 @@ static void perf_log_throttle(struct perf_event *event, int enable) > > perf_event_header__init_id(&throttle_event.header, &sample, event); > > + rctx = perf_swevent_get_recursion_context(); > ret = perf_output_begin(&handle, &sample, event, > throttle_event.header.size); > - if (ret) > - return; > + if (!ret) { > + perf_output_put(&handle, throttle_event); > + perf_event__output_id_sample(event, &handle, &sample); > + perf_output_end(&handle); > + } > > - perf_output_put(&handle, throttle_event); > - perf_event__output_id_sample(event, &handle, &sample); > - perf_output_end(&handle); > + if (rctx >= 0) > + perf_swevent_put_recursion_context(rctx); > } > > /* >