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Fri, 01 Nov 2019 18:52:39 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id xA1Iminu114420; Fri, 1 Nov 2019 18:52:39 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3030.oracle.com with ESMTP id 2w0qdwtd52-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 01 Nov 2019 18:52:39 +0000 Received: from abhmp0001.oracle.com (abhmp0001.oracle.com [141.146.116.7]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id xA1Iqanl023242; Fri, 1 Nov 2019 18:52:37 GMT Received: from bostrovs-us.us.oracle.com (/10.152.32.65) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 01 Nov 2019 11:52:36 -0700 Subject: Re: [PATCH v2 09/15] xen/gntdev: use mmu_range_notifier_insert To: Jason Gunthorpe Cc: "linux-mm@kvack.org" , Jerome Glisse , Ralph Campbell , John Hubbard , "Felix.Kuehling@amd.com" , "linux-rdma@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , "amd-gfx@lists.freedesktop.org" , Alex Deucher , Ben Skeggs , =?UTF-8?Q?Christian_K=c3=b6nig?= , David Zhou , Dennis Dalessandro , Juergen Gross , Mike Marciniszyn , Oleksandr Andrushchenko , Petr Cvek , Stefano Stabellini , "nouveau@lists.freedesktop.org" , "xen-devel@lists.xenproject.org" , Christoph Hellwig References: <20191028201032.6352-1-jgg@ziepe.ca> <20191028201032.6352-10-jgg@ziepe.ca> <0355257f-6a3a-cdcd-d206-aec3df97dded@oracle.com> <20191101174824.GP22766@mellanox.com> From: Boris Ostrovsky Openpgp: preference=signencrypt Autocrypt: addr=boris.ostrovsky@oracle.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20191101174824.GP22766@mellanox.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9428 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=2 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1911010171 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9428 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1911010171 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 11/1/19 1:48 PM, Jason Gunthorpe wrote: > On Wed, Oct 30, 2019 at 12:55:37PM -0400, Boris Ostrovsky wrote: >> On 10/28/19 4:10 PM, Jason Gunthorpe wrote: >>> From: Jason Gunthorpe >>> >>> gntdev simply wants to monitor a specific VMA for any notifier events, >>> this can be done straightforwardly using mmu_range_notifier_insert() over >>> the VMA's VA range. >>> >>> The notifier should be attached until the original VMA is destroyed. >>> >>> It is unclear if any of this is even sane, but at least a lot of duplicate >>> code is removed. >> I didn't have a chance to look at the patch itself yet but as a heads-up >> --- it crashes dom0. > Thanks Boris. I spent a bit of time and got a VM running with a xen > 4.9 hypervisor and a kernel with this patch series. It a ubuntu bionic > VM with the distro's xen stuff. > > Can you give some guidance how you made it crash? It crashes trying to dereference mrn->ops->invalidate in mn_itree_invalidate() when a guest exits. I don't think you've initialized notifier ops. I don't see you using gntdev_mmu_ops anywhere. -boris > I see the VM > autoloaded gntdev: > > Module Size Used by > xen_gntdev 24576 2 > xen_evtchn 16384 1 > xenfs 16384 1 > xen_privcmd 24576 16 xenfs > > And lsof says several xen processes have the chardev open: > > xenstored 819 root 13u CHR 10,53 0t0 19595 /dev/xen/gntdev > xenconsol 857 root 8u CHR 10,53 0t0 19595 /dev/xen/gntdev > xenconsol 857 860 root 8u CHR 10,53 0t0 19595 /dev/xen/gntdev > > But no crashing.. > > However, I wasn't able to get my usual debug kernel .config to boot > with the xen hypervisor, it crashes on early boot with: > > (XEN) Dom0 has maximum 8 VCPUs > (XEN) Scrubbing Free RAM on 1 nodes using 8 CPUs > (XEN) .done. > (XEN) Initial low memory virq threshold set at 0x1000 pages. > (XEN) Std. Loglevel: All > (XEN) Guest Loglevel: All > (XEN) *** Serial input -> DOM0 (type 'CTRL-a' three times to switch input to Xen) > (XEN) Freed 468kB init memory > (XEN) d0v0 Unhandled page fault fault/trap [#14, ec=0002] > (XEN) Pagetable walk from fffffbfff0480fbe: > (XEN) L4[0x1f7] = 0000000000000000 ffffffffffffffff > (XEN) domain_crash_sync called from entry.S: fault at ffff82d080348a06 entry.o#create_bounce_frame+0x135/0x15f > (XEN) Domain 0 (vcpu#0) crashed on cpu#0: > (XEN) ----[ Xen-4.9.2 x86_64 debug=n Not tainted ]---- > (XEN) CPU: 0 > (XEN) RIP: e033:[] > (XEN) RFLAGS: 0000000000000296 EM: 1 CONTEXT: pv guest (d0v0) > (XEN) rax: fffffbfff0480fbe rbx: 0000000000000000 rcx: 00000000c0000101 > (XEN) rdx: 00000000ffffffff rsi: ffffffff84026000 rdi: ffffffff82cb4a20 > (XEN) rbp: ffffffff82407ff8 rsp: ffffffff82407da0 r8: 0000000000000000 > (XEN) r9: 0000000000000000 r10: 0000000000000000 r11: 0000000000000000 > (XEN) r12: 0000000000000000 r13: 1ffffffff0480fbe r14: 0000000000000000 > (XEN) r15: 0000000000000000 cr0: 000000008005003b cr4: 00000000003506e0 > (XEN) cr3: 0000000034027000 cr2: fffffbfff0480fbe > (XEN) fsb: 0000000000000000 gsb: ffffffff82b61000 gss: 0000000000000000 > (XEN) ds: 0000 es: 0000 fs: 0000 gs: 0000 ss: e02b cs: e033 > > Which is surely some .config issue, but I didn't figure out what. > > Jason