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 EFF34C4360C for ; Thu, 1 Apr 2021 10:56:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CA3B5610E9 for ; Thu, 1 Apr 2021 10:56:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234082AbhDAKzb (ORCPT ); Thu, 1 Apr 2021 06:55:31 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:44745 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234062AbhDAKyS (ORCPT ); Thu, 1 Apr 2021 06:54:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617274420; 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=AeIuul5ZcJWK6eSi1peQ3Q3v2fRek8mT72TwlcJLzZg=; b=Lzcd2AeKwcPSJj8NaoIQD3UMXlomRjbiGtw/iQEt5iVFfvqk3d6znMcdOLJCIAQyYdTV+U +c/gbTLzGu53XCPMSvKKf/9jMvJKeVJYtQMI2PUDu/+7+LbpmWq5co6TVfsEfHIAxgnVDT lsb/L9V4IHjGEUtg7IBF12z41eEaUhE= 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-356-JYIJMMwvPASGaTacegJYRw-1; Thu, 01 Apr 2021 06:53:38 -0400 X-MC-Unique: JYIJMMwvPASGaTacegJYRw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 13AE483DD34; Thu, 1 Apr 2021 10:53:37 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.195.76]) by smtp.corp.redhat.com (Postfix) with SMTP id 9297117B15; Thu, 1 Apr 2021 10:53:31 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Thu, 1 Apr 2021 12:53:36 +0200 (CEST) Date: Thu, 1 Apr 2021 12:53:26 +0200 From: Oleg Nesterov To: Hillf Danton Cc: Namhyung Kim , Song Liu , Peter Zijlstra , syzbot , Srikar Dronamraju , Greg KH , linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] possible deadlock in register_for_each_vma Message-ID: <20210401105305.GA18680@redhat.com> References: <00000000000030aca605be6e0102@google.com> <20210327042150.7460-1-hdanton@sina.com> <20210328025217.7312-1-hdanton@sina.com> <20210401092907.1098-1-hdanton@sina.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210401092907.1098-1-hdanton@sina.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/01, Hillf Danton wrote: > > If I dont misread it, the lockdep chain will likely evolve from > > event_mutex -> uprobe.register_rwsem -> dup_mmap_sem -> mm.mmap_lock -> > event_mutex > to > dup_mmap_sem -> mm.mmap_lock -> dup_mmap_sem > > after this patch as both uprobe_register() and uprobe_unregister() would take > dup_mmap_sem. Hmm, please correct me, but I don't think so. I think mmap_lock -> dup_mmap_sem is not possible. Oleg.