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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 3790EC76188 for ; Tue, 23 Jul 2019 05:49:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 16C2A2229A for ; Tue, 23 Jul 2019 05:49:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726710AbfGWFtE (ORCPT ); Tue, 23 Jul 2019 01:49:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54676 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725788AbfGWFtE (ORCPT ); Tue, 23 Jul 2019 01:49:04 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8462F3083339; Tue, 23 Jul 2019 05:49:03 +0000 (UTC) Received: from [10.72.12.26] (ovpn-12-26.pek2.redhat.com [10.72.12.26]) by smtp.corp.redhat.com (Postfix) with ESMTP id 07AAE5B684; Tue, 23 Jul 2019 05:48:52 +0000 (UTC) Subject: Re: WARNING in __mmdrop To: "Michael S. Tsirkin" Cc: syzbot , aarcange@redhat.com, akpm@linux-foundation.org, christian@brauner.io, davem@davemloft.net, ebiederm@xmission.com, elena.reshetova@intel.com, guro@fb.com, hch@infradead.org, james.bottomley@hansenpartnership.com, jglisse@redhat.com, keescook@chromium.org, ldv@altlinux.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-parisc@vger.kernel.org, luto@amacapital.net, mhocko@suse.com, mingo@kernel.org, namit@vmware.com, peterz@infradead.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk, wad@chromium.org References: <0000000000008dd6bb058e006938@google.com> <000000000000964b0d058e1a0483@google.com> <20190721044615-mutt-send-email-mst@kernel.org> <75c43998-3a1c-676f-99ff-3d04663c3fcc@redhat.com> <20190722035657-mutt-send-email-mst@kernel.org> <20190723010156-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: <124be1a2-1c53-8e65-0f06-ee2294710822@redhat.com> Date: Tue, 23 Jul 2019 13:48:52 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190723010156-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Tue, 23 Jul 2019 05:49:03 +0000 (UTC) Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On 2019/7/23 下午1:02, Michael S. Tsirkin wrote: > On Tue, Jul 23, 2019 at 11:55:28AM +0800, Jason Wang wrote: >> On 2019/7/22 下午4:02, Michael S. Tsirkin wrote: >>> On Mon, Jul 22, 2019 at 01:21:59PM +0800, Jason Wang wrote: >>>> On 2019/7/21 下午6:02, Michael S. Tsirkin wrote: >>>>> On Sat, Jul 20, 2019 at 03:08:00AM -0700, syzbot wrote: >>>>>> syzbot has bisected this bug to: >>>>>> >>>>>> commit 7f466032dc9e5a61217f22ea34b2df932786bbfc >>>>>> Author: Jason Wang >>>>>> Date: Fri May 24 08:12:18 2019 +0000 >>>>>> >>>>>> vhost: access vq metadata through kernel virtual address >>>>>> >>>>>> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=149a8a20600000 >>>>>> start commit: 6d21a41b Add linux-next specific files for 20190718 >>>>>> git tree: linux-next >>>>>> final crash: https://syzkaller.appspot.com/x/report.txt?x=169a8a20600000 >>>>>> console output: https://syzkaller.appspot.com/x/log.txt?x=129a8a20600000 >>>>>> kernel config: https://syzkaller.appspot.com/x/.config?x=3430a151e1452331 >>>>>> dashboard link: https://syzkaller.appspot.com/bug?extid=e58112d71f77113ddb7b >>>>>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10139e68600000 >>>>>> >>>>>> Reported-by: syzbot+e58112d71f77113ddb7b@syzkaller.appspotmail.com >>>>>> Fixes: 7f466032dc9e ("vhost: access vq metadata through kernel virtual >>>>>> address") >>>>>> >>>>>> For information about bisection process see: https://goo.gl/tpsmEJ#bisection >>>>> OK I poked at this for a bit, I see several things that >>>>> we need to fix, though I'm not yet sure it's the reason for >>>>> the failures: >>>>> >>>>> >>>>> 1. mmu_notifier_register shouldn't be called from vhost_vring_set_num_addr >>>>> That's just a bad hack, >>>> This is used to avoid holding lock when checking whether the addresses are >>>> overlapped. Otherwise we need to take spinlock for each invalidation request >>>> even if it was the va range that is not interested for us. This will be very >>>> slow e.g during guest boot. >>> KVM seems to do exactly that. >>> I tried and guest does not seem to boot any slower. >>> Do you observe any slowdown? >> >> Yes I do. >> >> >>> Now I took a hard look at the uaddr hackery it really makes >>> me nervious. So I think for this release we want something >>> safe, and optimizations on top. As an alternative revert the >>> optimization and try again for next merge window. >> >> Will post a series of fixes, let me know if you're ok with that. >> >> Thanks > I'd prefer you to take a hard look at the patch I posted > which makes code cleaner, I did. But it looks to me a series that is only about 60 lines of code can fix all the issues we found without reverting the uaddr optimization. > and ad optimizations on top. > But other ways could be ok too. I'm waiting for the test result from syzbot and will post. Let's see if you are OK with that. Thanks >>> 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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 83C4EC76188 for ; Tue, 23 Jul 2019 05:49:16 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 593892229A for ; Tue, 23 Jul 2019 05:49:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="dBOHbPZR" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 593892229A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=kIT4Y8TYmP87LxZqDlDffN3Dkil9mENmY8LY1RAbV9g=; b=dBOHbPZRJEx28z7bR6xGkr2qk FRFgFAAq8B/D/PEra7pdOXze78zzVCRt8lO2HhjwiJ5P1z/YIUQLhgLp17YCTuK+Qmru80mcHWAFv lBacfWLJsYfq3tJA1e4iiclvqMTiAWywC/jlh9P5b9ZbGTtO8A/80S5HMxalnQJ+317Npw9LBm5bE tygw8H6OTm4exFpGBAW2MWHnWTKMFheS6IxLUO0eK6Mrf14UGTMJ1XF9RSztTi9LX417nWlJrKOZq GZky8u01ZSiIyN/8syL69VoEnczCRupvchxU5JWksz3xvRzJ+yh74YAJm1Et6SyXymIephr7S2n7e ZzDIp2mvw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hpnfg-0001cM-Km; Tue, 23 Jul 2019 05:49:08 +0000 Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hpnfc-0001bZ-0Y for linux-arm-kernel@lists.infradead.org; Tue, 23 Jul 2019 05:49:06 +0000 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8462F3083339; Tue, 23 Jul 2019 05:49:03 +0000 (UTC) Received: from [10.72.12.26] (ovpn-12-26.pek2.redhat.com [10.72.12.26]) by smtp.corp.redhat.com (Postfix) with ESMTP id 07AAE5B684; Tue, 23 Jul 2019 05:48:52 +0000 (UTC) Subject: Re: WARNING in __mmdrop To: "Michael S. Tsirkin" References: <0000000000008dd6bb058e006938@google.com> <000000000000964b0d058e1a0483@google.com> <20190721044615-mutt-send-email-mst@kernel.org> <75c43998-3a1c-676f-99ff-3d04663c3fcc@redhat.com> <20190722035657-mutt-send-email-mst@kernel.org> <20190723010156-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: <124be1a2-1c53-8e65-0f06-ee2294710822@redhat.com> Date: Tue, 23 Jul 2019 13:48:52 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190723010156-mutt-send-email-mst@kernel.org> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Tue, 23 Jul 2019 05:49:03 +0000 (UTC) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190722_224904_618538_7FCAE6BB X-CRM114-Status: GOOD ( 18.21 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mhocko@suse.com, peterz@infradead.org, ldv@altlinux.org, james.bottomley@hansenpartnership.com, linux-mm@kvack.org, namit@vmware.com, mingo@kernel.org, elena.reshetova@intel.com, keescook@chromium.org, aarcange@redhat.com, davem@davemloft.net, hch@infradead.org, christian@brauner.io, syzbot , syzkaller-bugs@googlegroups.com, jglisse@redhat.com, viro@zeniv.linux.org.uk, linux-arm-kernel@lists.infradead.org, wad@chromium.org, linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org, luto@amacapital.net, ebiederm@xmission.com, akpm@linux-foundation.org, guro@fb.com Content-Transfer-Encoding: base64 Content-Type: text/plain; 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