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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 D9472C432C3 for ; Wed, 20 Nov 2019 17:33:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A4DE020730 for ; Wed, 20 Nov 2019 17:33:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="jI9SwzAl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728452AbfKTRdU (ORCPT ); Wed, 20 Nov 2019 12:33:20 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:37469 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728072AbfKTRdU (ORCPT ); Wed, 20 Nov 2019 12:33:20 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574271199; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8nR1ThSYkPSj6EKFsdnP0qYjK76PkXaOodYqjHyh+W0=; b=jI9SwzAl31T4SgOtx+le6OomISUgEos1uLtZ6tgzDUOL6qlyXfTt2HuQI35906rbok/K4n hXH0eykZqQ98YqWA8USOcAI7ngfyOELKEHLSiART44mHkr7RqnhnFkb0Qu0ZZBpQ3nuSEY Ru0a9CaUDbyg8XO2COTOOXHtbdz+LhE= 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-147-t-OIAHNFMFmrkkvPBSjsMQ-1; Wed, 20 Nov 2019 12:33:18 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B82708018A3; Wed, 20 Nov 2019 17:33:15 +0000 (UTC) Received: from suzdal.zaitcev.lan (ovpn-117-3.phx2.redhat.com [10.3.117.3]) by smtp.corp.redhat.com (Postfix) with ESMTP id D86D42AAB4; Wed, 20 Nov 2019 17:33:14 +0000 (UTC) Date: Wed, 20 Nov 2019 11:33:14 -0600 From: Pete Zaitcev To: Alan Stern Cc: syzbot , arnd@arndb.de, , , , , Kernel development list , USB list , , , , zaitcev@redhat.com Subject: Re: possible deadlock in mon_bin_vma_fault Message-ID: <20191120113314.761fce32@suzdal.zaitcev.lan> In-Reply-To: References: <0000000000002da08e0597c5efbd@google.com> Organization: Red Hat, Inc. MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-MC-Unique: t-OIAHNFMFmrkkvPBSjsMQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 20 Nov 2019 11:14:05 -0500 (EST) Alan Stern wrote: > As it happens, I spent a little time investigating this bug report just > yesterday. It seems to me that the easiest fix would be to disallow > resizing the buffer while it is mapped by any users. (Besides, > allowing that seems like a bad idea in any case.) >=20 > Pete, does that seem reasonable to you? Actually, please hold on a little, I think to think more about this. The deadlock is between mon_bin_read and mon_bin_vma_fault. To disallow resizing isn't going to fix _that_. -- Pete