Hello, I'm experimenting with bcache within a virtual machine, before using it on a real machine. I compiled the kernel (plain stock 3.18 from kernel.org) myself and I am running a para-virtualized kernel on top of XEN 4.4. When initially running: # make-bcache -C /dev/xvdc the kernel spits out the following: [ 93.748215] ------------[ cut here ]------------ [ 93.748741] kernel BUG at drivers/md/bcache/super.c:1840! [ 93.749163] invalid opcode: 0000 [#1] SMP [ 93.749592] Modules linked in: nfsd auth_rpcgss oid_registry nfs_acl nfs lockd grace fscache sunrpc bridge stp llc loop snd_pcm snd_timer snd soundcore thermal_sys evdev pcspkr joydev ext4 crc16 mbcache jbd2 dm_mod bcache xen_netfront xen_blkfront [ 93.750946] CPU: 2 PID: 2265 Comm: bcache-register Not tainted 3.18.0 #2 [ 93.751492] task: dcab2560 ti: debc6000 task.ti: debc6000 [ 93.751939] EIP: 0061:[<e0ae5510>] EFLAGS: 00010246 CPU: 2 [ 93.752121] EIP is at register_bcache+0x11e0/0x2170 [bcache] [ 93.752121] EAX: c25129c0 EBX: c25d8000 ECX: 0000002f EDX: dfb16e70 [ 93.752121] ESI: 00000000 EDI: 00000008 EBP: debc7f14 ESP: debc7e40 [ 93.752121] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0069 [ 93.752121] CR0: 8005003b CR2: 086922dc CR3: 1e8a8000 CR4: 00000620 [ 93.752121] Stack: [ 93.752121] 00001000 00000008 dcd60580 ffffffff 00000000 debc7e88 c1005f1a 00000022 [ 93.752121] dcd60580 01000100 c2499490 c387d848 00000000 00000000 00000000 dcd27038 [ 93.752121] dcd27028 00000000 00000000 dcd27018 debc7eac c25d8938 00000000 00000000 [ 93.752121] Call Trace: [ 93.752121] [<c1005f1a>] ? xen_batched_set_pte+0x1a/0x160 [ 93.752121] [<c114c8d4>] ? handle_mm_fault+0x524/0xf10 [ 93.752121] [<c116a3b4>] ? __kmalloc+0x94/0x5d0 [ 93.752121] [<e0ae4330>] ? bch_cache_set_alloc+0x4f0/0x4f0 [bcache] [ 93.752121] [<c126ec25>] ? kobj_attr_store+0x15/0x30 [ 93.752121] [<c11e23e5>] ? sysfs_kf_write+0x35/0x50 [ 93.752121] [<c11e23b0>] ? sysfs_kf_bin_read+0xc0/0xc0 [ 93.752121] [<c11e17c7>] ? kernfs_fop_write+0xc7/0x150 [ 93.752121] [<c11e23b0>] ? sysfs_kf_bin_read+0xc0/0xc0 [ 93.752121] [<c11e1700>] ? kernfs_vma_page_mkwrite+0x80/0x80 [ 93.752121] [<c117eb9e>] ? vfs_write+0x9e/0x1e0 [ 93.752121] [<c118f3dc>] ? do_fcntl+0x36c/0x510 [ 93.752121] [<c117f166>] ? SyS_write+0x46/0x90 [ 93.752121] [<c14aa45f>] ? sysenter_do_call+0x12/0x12 [ 93.752121] Code: 0f 85 bf fa ff ff e9 b2 fa ff ff 0f 0b 8b 44 24 6c e8 a5 b9 64 e0 84 c0 0f 85 42 f4 ff ff e9 35 f4 ff ff 90 8d b4 26 00 00 00 00 <0f> 0b 8b bc 24 80 00 00 00 be 0a f0 ae e0 b8 24 54 af e0 e8 d8 [ 93.752121] EIP: [<e0ae5510>] register_bcache+0x11e0/0x2170 [bcache] SS:ESP 0069:debc7e40 [ 93.767489] ---[ end trace bacc83d385d551aa ]--- Running: # bcache-super-show /dev/xvdc then produces: sb.magic ok sb.first_sector 8 [match] sb.csum C645C4895EA701F1 [match] sb.version 0 [cache device] dev.label (empty) dev.uuid 2e549ac6-b553-430e-8d79-9914bc4b067d dev.sectors_per_block 1 dev.sectors_per_bucket 1024 dev.cache.first_sector 1024 dev.cache.cache_sectors 203776 dev.cache.total_sectors 204800 dev.cache.ordered no dev.cache.discard no dev.cache.pos 0 dev.cache.replacement 0 [lru] cset.uuid 0f1049f1-fa57-4593-8e8d-e1cdab17a847 The backing device worked fine. # make-bcache -B /dev/xvdd produced at the next boot: [ 2.733692] bcache: register_bdev() registered backing device xvdd However, I get other OOPses when I reboot with my unregistered xvdc caching device: [ 2.467772] ------------[ cut here ]------------ [ 2.467825] kernel BUG at drivers/md/bcache/super.c:1840! [ 2.467849] invalid opcode: 0000 [#1] SMP [ 2.467874] Modules linked in: bcache xen_netfront xen_blkfront [ 2.467909] CPU: 0 PID: 110 Comm: bcache-register Not tainted 3.18.0 #2 [ 2.467951] task: dcac4560 ti: dcace000 task.ti: dcace000 [ 2.468008] EIP: 0061:[<e0af1510>] EFLAGS: 00010246 CPU: 0 [ 2.468062] EIP is at register_bcache+0x11e0/0x2170 [bcache] [ 2.468086] EAX: c24e5ea0 EBX: c25d6000 ECX: 00000055 EDX: dfaf6e70 [ 2.468111] ESI: 00000000 EDI: 00000008 EBP: dcacff14 ESP: dcacfe40 [ 2.468137] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0069 [ 2.468173] CR0: 8005003b CR2: b75eb017 CR3: 025dc000 CR4: 00000620 [ 2.468207] Stack: [ 2.468231] 00001000 00000008 dfb24000 c25e83d8 00000037 c25e83d8 dcacfec0 c114b5c9 [ 2.468289] de1f0dc0 01000100 de32a350 dfb6fd00 00000000 00000000 00000000 dcb88038 [ 2.468348] dcb88028 00000000 00000000 dcb88018 08070000 c25d6938 00000000 00000000 [ 2.468387] Call Trace: [ 2.468417] [<c114b5c9>] ? do_read_fault.isra.69+0x2f9/0x340 [ 2.468453] [<c114cbc7>] ? handle_mm_fault+0x817/0xf10 [ 2.468482] [<c116a3b4>] ? __kmalloc+0x94/0x5d0 [ 2.468510] [<e0af0330>] ? bch_cache_set_alloc+0x4f0/0x4f0 [bcache] [ 2.468543] [<c126ec25>] ? kobj_attr_store+0x15/0x30 [ 2.468573] [<c11e23e5>] ? sysfs_kf_write+0x35/0x50 [ 2.468602] [<c11e23b0>] ? sysfs_kf_bin_read+0xc0/0xc0 [ 2.468637] [<c11e17c7>] ? kernfs_fop_write+0xc7/0x150 [ 2.468664] [<c11e23b0>] ? sysfs_kf_bin_read+0xc0/0xc0 [ 2.468691] [<c11e1700>] ? kernfs_vma_page_mkwrite+0x80/0x80 [ 2.468721] [<c117eb9e>] ? vfs_write+0x9e/0x1e0 [ 2.468746] [<c117f166>] ? SyS_write+0x46/0x90 [ 2.468773] [<c14aa549>] ? syscall_call+0x7/0x7 [ 2.468793] Code: 0f 85 bf fa ff ff e9 b2 fa ff ff 0f 0b 8b 44 24 6c e8 a5 f9 63 e0 84 c0 0f 85 42 f4 ff ff e9 35 f4 ff ff 90 8d b4 26 00 00 00 00 <0f> 0b 8b bc 24 80 00 00 00 be 0a b0 af e0 b8 24 14 b0 e0 e8 d8 [ 2.470510] EIP: [<e0af1510>] register_bcache+0x11e0/0x2170 [bcache] SS:ESP 0069:dcacfe40 [ 2.471290] ---[ end trace e787c07ea8fae3da ]--- How can I assist you into nailing down this bug? Thanks, Raphael -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
