bcache causes a Kernel Bug when adding a new cache device

[jackywang]

Ubuntu 16.04 on virtualbox 5.0.20. VirtualBoxAddition is installed.

The issue happens on both out-of-box 4.4.0 kernel and the later-installed 4.4.11 kernel. 100% re-producible. The same issue applies to both virtual hard drive (/dev/sdb) and file-base block device (/dev/loop2) I created within Ubuntu.

On Arch Linux on virtual box 5.0.20, without VirtualBoxAddition installed, this issue is reproducible too on kernel 4.5.4.

$ sudo make-bcache -C /dev/sdb

The error shows (through dmesg):

[ 47.616016] ------------[ cut here ]------------
[ 47.616035] kernel BUG at /home/kernel/COD/linux/drivers/md/bcache/super.c:1822!
[ 47.616051] invalid opcode: 0000 [#1] SMP
[ 47.616063] Modules linked in: vboxsf(OE) ppdev vboxvideo(OE) ttm drm_kms_helper input_leds joydev drm serio_raw lpc_ich fb_sys_fops syscopyarea i2c_piix4 sysfillrect sysimgblt 8250_fintek parport_pc vboxguest(OE) parport mac_hid ib_iser rdma_cm iw_cm ib_cm ib_sa ib_mad ib_core ib_addr iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi autofs4 btrfs raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 multipath linear bcache raid0 hid_generic usbhid hid crct10dif_pclmul crc32_pclmul aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd psmouse fjes ahci libahci pata_acpi video
[ 47.616255] CPU: 2 PID: 1247 Comm: bcache-register Tainted: G OE 4.4.11-040411-generic #201605182255
[ 47.616277] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[ 47.616295] task: ffff880035140000 ti: ffff880076840000 task.ti: ffff880076840000
[ 47.616311] RIP: 0010:[<ffffffffc0134086>] [<ffffffffc0134086>] cache_alloc.isra.20+0x646/0x670 [bcache]
[ 47.616340] RSP: 0018:ffff880076843d10 EFLAGS: 00010246
[ 47.616352] RAX: ffff880079528c60 RBX: ffff8800796a0000 RCX: 00000000000005d2
[ 47.616367] RDX: 00000000000005d1 RSI: 0000000000000000 RDI: 0000000000019d40
[ 47.616382] RBP: ffff880076843d28 R08: ffff88007fd19d40 R09: ffff88007d001d00
[ 47.616398] R10: ffff880079528c60 R11: ffff88007b590958 R12: 0000000000000000
[ 47.616413] R13: 0000000000000010 R14: ffff88007c3c4000 R15: ffff8800796a0000
[ 47.616428] FS: 00007ff8ffa10700(0000) GS:ffff88007fd00000(0000) knlGS:0000000000000000
[ 47.616445] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 47.616458] CR2: 00007ff8ff4c1d30 CR3: 0000000077f70000 CR4: 00000000000406e0
[ 47.616476] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 47.616491] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 47.616506] Stack:
[ 47.616511] ffffea0001e880c0 ffff88007cc28680 0000000000000000 ffff880076843dd0
[ 47.616531] ffffffffc01373e3 ffff880076843d58 ffffffff811c8de5 000000007fd61025
[ 47.616551] 00007ff8ff4cf000 ffff88007b590958 ffff8800796a0008 0000000000000009
[ 47.616570] Call Trace:
[ 47.616585] [<ffffffffc01373e3>] register_bcache+0x2b3/0x1140 [bcache]
[ 47.616626] [<ffffffff811c8de5>] ? page_add_file_rmap+0x25/0x60
[ 47.617074] [<ffffffff8118b7b9>] ? unlock_page+0x69/0x70
[ 47.617516] [<ffffffff813d25ef>] kobj_attr_store+0xf/0x20
[ 47.617946] [<ffffffff81289147>] sysfs_kf_write+0x37/0x40
[ 47.618353] [<ffffffff8128855d>] kernfs_fop_write+0x11d/0x170
[ 47.618755] [<ffffffff81209a27>] __vfs_write+0x37/0x110
[ 47.619149] [<ffffffff8137a238>] ? apparmor_file_permission+0x18/0x20
[ 47.619543] [<ffffffff8133aead>] ? security_file_permission+0x3d/0xc0
[ 47.619922] [<ffffffff810c8f12>] ? percpu_down_read+0x12/0x50
[ 47.620290] [<ffffffff8120a139>] vfs_write+0xa9/0x1a0
[ 47.620648] [<ffffffff8120adf5>] SyS_write+0x55/0xc0
[ 47.621021] [<ffffffff81808332>] entry_SYSCALL_64_fastpath+0x16/0x71
[ 47.621362] Code: 6a fd ff ff e9 4d fd ff ff be c0 00 40 02 4c 89 e7 e8 cf 61 0b c1 48 85 c0 48 89 83 f0 0a 00 00 0f 85 96 fd ff ff e9 79 fd ff ff <0f> 0b 0f 0b 0f 0b bf 40 00 00 00 e8 9a 90 09 c1 48 85 c0 48 89
[ 47.622456] RIP [<ffffffffc0134086>] cache_alloc.isra.20+0x646/0x670 [bcache]
[ 47.622812] RSP <ffff880076843d10>
[ 47.623177] ---[ end trace 19bcd02731ac9be1 ]---

[Frank Mehnert]

Cannot reproduce with Ubuntu 16.04 / 32-bit. VBox.log file please. At the moment I'm not convinced that this is a VirtualBox bug at all.

[aeichner]

Can't reproduce either, please reopen if still relevant attaching at least a VBox.log from the affected VM.