Hi, I know this isn't a valid use case or generally sane thing to do, but we have a bug (link, with details, below) filed for a panic against a detach-disk/attach-disk sequence of an ext4 mounted vd device on a rhel kernel. The same sequence leads to the following BUG on an upstream kernel (3.7.0-rc5+ SMP x86_64 GNU/Linux): [ 75.114951] BUG: unable to handle kernel NULL pointer dereference at 0000000000000090 [ 75.114957] IP: [<ffffffff8136ae35>] virtio_check_driver_offered_feature+0x5/0x50 [ 75.114986] PGD 117b99067 PUD 114daa067 PMD 0 [ 75.114992] Oops: 0000 [#1] SMP [ 75.115006] Modules linked in: be2iscsi iscsi_boot_sysfs bnx2i fcoe libfcoe libfc cnic uio lockd cxgb4i cxgb4 scsi_transport_fc cxgb3i scsi_tgt libcxgbi cxgb3 8021q garp stp llc mdio ib_iser rdma_cm ib_cm iw_cm ib_sa ib_mad ib_core ib_addr iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi snd_hda_intel snd_hda_codec snd_hwdep snd_seq snd_seq_device snd_pcm joydev snd_timer snd microcode soundcore pcspkr virtio_net virtio_balloon 9pnet_virtio 9pnet snd_page_alloc i2c_piix4 i2c_core uinput sunrpc floppy [ 75.115042] CPU 0 [ 75.115047] Pid: 1264, comm: blkid Not tainted 3.7.0-rc5+ #149 Bochs Bochs [ 75.115049] RIP: 0010:[<ffffffff8136ae35>] [<ffffffff8136ae35>] virtio_check_driver_offered_feature+0x5/0x50 [ 75.115055] RSP: 0018:ffff880118c6bde0 EFLAGS: 00010286 [ 75.115055] RAX: ffff880117838000 RBX: ffff88011ac28680 RCX: 0000000000000000 [ 75.115058] RDX: 0000000000005331 RSI: 0000000000000007 RDI: 0000000000000000 [ 75.115058] RBP: ffff880118c6be18 R08: 0000000000005331 R09: 000000000000101d [ 75.115060] R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000101d [ 75.115060] R13: 0000000000005331 R14: 0000000000000000 R15: 0000000000000000 [ 75.115063] FS: 00007fb5ccf80740(0000) GS:ffff88011fc00000(0000) knlGS:0000000000000000 [ 75.115064] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 75.115066] CR2: 0000000000000090 CR3: 000000011786b000 CR4: 00000000000006f0 [ 75.115073] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 75.115077] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 75.115079] Process blkid (pid: 1264, threadinfo ffff880118c6a000, task ffff880115a3c530) [ 75.115080] Stack: [ 75.115081] ffffffff813d0bfb ffff880118c6bf58 0000000000005331 00000000ffffffe7 [ 75.115084] 0000000000000000 ffff88011ac28680 ffff88011ab5d000 ffff880118c6be78 [ 75.115087] ffffffff812bd1be ffff880115a85180 ffff88011ac28680 ffff880118c6bee8 [ 75.115090] Call Trace: [ 75.115101] [<ffffffff813d0bfb>] ? virtblk_ioctl+0x4b/0x90 [ 75.115118] [<ffffffff812bd1be>] blkdev_ioctl+0xde/0x830 [ 75.115130] [<ffffffff8118b406>] ? cp_new_stat+0x116/0x130 [ 75.115140] [<ffffffff811bc940>] block_ioctl+0x40/0x50 [ 75.115146] [<ffffffff81197ac8>] do_vfs_ioctl+0x98/0x550 [ 75.115149] [<ffffffff81198011>] sys_ioctl+0x91/0xb0 [ 75.115162] [<ffffffff810db086>] ? __audit_syscall_exit+0x3d6/0x410 [ 75.115175] [<ffffffff81625519>] system_call_fastpath+0x16/0x1b [ 75.115176] Code: 4c 8b 60 18 ff 50 10 83 c8 80 48 89 df 0f b6 f0 41 ff d4 eb cb 90 0f 1f 44 00 00 55 48 89 e5 e8 d2 18 05 00 5d c3 0f 1f 44 00 00 <48> 8b 87 90 00 00 00 55 48 89 e5 8b 88 80 00 00 00 85 c9 74 26 [ 75.115203] RIP [<ffffffff8136ae35>] virtio_check_driver_offered_feature+0x5/0x50 [ 75.115206] RSP <ffff880118c6bde0> [ 75.115207] CR2: 0000000000000090 [ 75.115247] ---[ end trace f2226e229a762cf5 ]--- I suppose it's not a critical issue, but I'm reporting in the event that there are any thoughts on improved error handling in this scenario. Thanks. (Please CC me on replies). Brian * - https://bugzilla.redhat.com/show_bug.cgi?id=867280 _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
