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=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 50F89C433B4 for ; Tue, 6 Apr 2021 17:23:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 223786139E for ; Tue, 6 Apr 2021 17:23:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346875AbhDFRXo (ORCPT ); Tue, 6 Apr 2021 13:23:44 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:38727 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232593AbhDFRXm (ORCPT ); Tue, 6 Apr 2021 13:23:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617729813; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=kRqtUNrfsS+HN0qfeBVlZNBL6W5/ImsXWPSzbVRKt/s=; b=RO4IpaVKqPxsFdb7Wx/Yi0Y76KDQ7oRpyPP5ID4Kt7VhSqFKNEwBg29t7BCxu1fAZsiTvk Zh81qSwPIWiC3WBnn1h6ef5angQooYzyCBYocoSKqP4QoaNU2B0Ev/HnqBfNnsbeHs9RO5 OPHqCRiANgI8YGr4U1e3Iv5SWPZBrkg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-299-KqAku7wLMu2Mn_cMrPZxxQ-1; Tue, 06 Apr 2021 13:23:29 -0400 X-MC-Unique: KqAku7wLMu2Mn_cMrPZxxQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B1D3E1007468; Tue, 6 Apr 2021 17:23:27 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.192.43]) by smtp.corp.redhat.com (Postfix) with SMTP id 4F74410016DB; Tue, 6 Apr 2021 17:23:24 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 6 Apr 2021 19:23:27 +0200 (CEST) Date: Tue, 6 Apr 2021 19:23:23 +0200 From: Oleg Nesterov To: Hillf Danton , Song Liu , Peter Zijlstra Cc: Namhyung Kim , syzbot , Srikar Dronamraju , Greg KH , linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: perf_mmap_close() -> put_event() -> event.destroy() can deadlock Message-ID: <20210406172322.GA13270@redhat.com> References: <00000000000030aca605be6e0102@google.com> <20210327042150.7460-1-hdanton@sina.com> <20210328025217.7312-1-hdanton@sina.com> <20210401092907.1098-1-hdanton@sina.com> <20210402074636.1270-1-hdanton@sina.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210402074636.1270-1-hdanton@sina.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Song, Peter, please take a look. On 04/02, Hillf Danton wrote: > > On Thu, 1 Apr 2021 12:53:26 Oleg Nesterov wrote: > > > >Hmm, please correct me, but I don't think so. I think mmap_lock -> dup_mmap_sem > >is not possible. > > > Given perf_trace_destroy() in the report, it is a couple of steps in the > subsequent call chain that it likely takes to reach uprobe_unregister(). > > perf_trace_destroy() > perf_trace_event_unreg(p_event) > tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL); > trace_uprobe_register() Well, this is not possible, perf_trace_destroy() is only used by perf_tracepoint pmu. But you are right anyway, event.destroy == perf_uprobe_destroy can lead to uprobe_unregister(). Thanks. ------------------------------------------------------------------------------- So. perf_mmap_close() does put_event(event) with mm->mmap_lock held. This can deadlock if event->destroy == perf_uprobe_destroy: perf_trace_event_close/unreg takes dup_mmap_sem. perf_mmap_close() was added by 9bb5d40cd93c9 ("perf: Fix mmap() accounting hole") and this commit doesn't look right anyway, I'll write another email. However, it seems that this particular problem was added later by 33ea4b24277b0 ("perf/core: Implement the 'perf_uprobe' PMU"). Oleg.