From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vitaly Kuznetsov Subject: Re: Failure to boot HVM guest with more than 32 VCPUS Date: Thu, 13 Aug 2015 11:20:57 +0200 Message-ID: <87oaibee86.fsf@vitty.brq.redhat.com> References: <87mvxwq20c.fsf@vitty.brq.redhat.com> <874mk3fvlw.fsf@vitty.brq.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: (Xudong Hao's message of "Thu, 13 Aug 2015 08:37:24 +0000") List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: "Hao, Xudong" Cc: "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org "Hao, Xudong" writes: > > Attach the Fedora22 log, a different issue. > Here is the crash: [ 6399.814801] xen_netfront: Initialising Xen virtual ethernet driver [ 6399.814838] [drm] Initialized drm 1.1.0 20060810 [ 6399.838500] xen_netfront: can't alloc rx grant refs [ 6399.838504] net eth0: only created 31 queues [ 6399.839930] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 [ 6399.839938] IP: [] netback_changed+0x8eb/0xef0 [xen_netfront] [ 6399.839940] PGD 0 [ 6399.839943] Oops: 0000 [#1] SMP [ 6399.839948] Modules linked in: drm xen_netfront(+) xen_blkfront(+) crc32c_intel ata_generic pata_acpi [ 6399.839955] CPU: 0 PID: 241 Comm: xenwatch Not tainted 4.0.4-301.fc22.x86_64 #1 [ 6399.839957] Hardware name: Xen HVM domU, BIOS 4.6.0-rc 08/13/2015 [ 6399.839959] task: ffff880107ffc590 ti: ffff880107920000 task.ti: ffff880107920000 [ 6399.839963] RIP: 0010:[] [] netback_changed+0x8eb/0xef0 [xen_netfront] [ 6399.839965] RSP: 0000:ffff880107923d68 EFLAGS: 00010202 [ 6399.839966] RAX: 0000000000000000 RBX: ffff8800e6568000 RCX: 0000000000000001 [ 6399.839968] RDX: 00000000000e6568 RSI: ffff8800e65c40f8 RDI: 0000000000003f41 [ 6399.839969] RBP: ffff880107923df8 R08: ffffc90000940000 R09: 0000000000000000 [ 6399.839971] R10: ffffea0003995a00 R11: 0000000000100000 R12: ffff8800e65c4000 [ 6399.839972] R13: ffff8800e65c40f8 R14: ffff8800e6567000 R15: 0000000000044000 [ 6399.839974] FS: 0000000000000000(0000) GS:ffff880109600000(0000) knlGS:0000000000000000 [ 6399.839975] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 6399.839977] CR2: 0000000000000018 CR3: 0000000001c0b000 CR4: 00000000001407f0 [ 6399.839980] Stack: [ 6399.839983] ffff880107923d78 ffff8800e65c1e04 ffff8800e65c1f21 ffff8800eb8b1400 [ 6399.839985] ffff8800e73d8000 ffff8800eb8b1400 0000002107923dec ffff880000000020 [ 6399.839988] 0000000107ffc590 0000004000000001 ffff8800ebb261f1 0000000087ee3bd9 [ 6399.839989] Call Trace: [ 6399.839998] [] xenbus_otherend_changed+0xad/0x120 [ 6399.840014] [] ? prepare_to_wait_event+0x87/0x100 [ 6399.840017] [] ? unregister_xenbus_watch+0x1d0/0x1d0 [ 6399.840021] [] backend_changed+0x13/0x20 [ 6399.840023] [] xenwatch_thread+0x8f/0x150 [ 6399.840026] [] ? wake_atomic_t_function+0x70/0x70 [ 6399.840031] [] kthread+0xd8/0xf0 [ 6399.840035] [] ? kthread_worker_fn+0x180/0x180 [ 6399.840041] [] ret_from_fork+0x58/0x90 [ 6399.840044] [] ? kthread_worker_fn+0x180/0x180 [ 6399.840056] Code: 48 8b 04 f0 48 83 f8 ff 0f 84 e2 04 00 00 48 89 c6 48 b8 ff ff ff ff ff ff ff 3f 48 21 c6 e9 ad fd ff ff 49 8b 44 24 20 4c 89 ee <48> 8b 78 18 e8 fc ee 2c e1 85 c0 0f 88 be fd ff ff 49 8b 44 24 [ 6399.840059] RIP [] netback_changed+0x8eb/0xef0 [xen_netfront] [ 6399.840060] RSP [ 6399.840061] CR2: 0000000000000018 [ 6399.840064] ---[ end trace 790f9d91e3f3059b ]--- The main issue (I suppose) is: [ 6399.838500] xen_netfront: can't alloc rx grant refs it happens when gnttab_alloc_grant_references() fails. As far as I can see it can only happen when gnttab_expand() fails. Do you have anything in your Xen dmesg ('xl dmegs' output on your host)? In case not, can you try increasing you guest's memory to see if the issue goes away? -- Vitaly