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[79.181.91.42]) by smtp.gmail.com with ESMTPSA id i62sm22519634qke.52.2019.07.24.23.02.44 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 24 Jul 2019 23:02:50 -0700 (PDT) Date: Thu, 25 Jul 2019 02:02:41 -0400 From: "Michael S. Tsirkin" To: Jason Gunthorpe 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, jasowang@redhat.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 Subject: Re: WARNING in __mmdrop Message-ID: <20190725015402-mutt-send-email-mst@kernel.org> References: <0000000000008dd6bb058e006938@google.com> <000000000000964b0d058e1a0483@google.com> <20190721044615-mutt-send-email-mst@kernel.org> <20190722141152.GA13711@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190722141152.GA13711@ziepe.ca> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Jul 22, 2019 at 11:11:52AM -0300, Jason Gunthorpe wrote: > On Sun, Jul 21, 2019 at 06:02:52AM -0400, 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: > > This stuff looks quite similar to the hmm_mirror use model and other > places in the kernel. I'm still hoping we can share this code a bit more. Right. I think hmm is something we should look at. -- MST