FYI, we noticed the following commit: commit: 8eea81e0903fcde1c28044ea66acc4c5c578f553 ("scsi: enable IO scheduling for scsi-mq") https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git blk-mq-legacy-sched.1 in testcase: boot on test machine: qemu-system-i386 -enable-kvm -cpu Haswell,+smep,+smap -m 360M caused below changes: +------------------------------------------------+------------+------------+ | | 4fecac6753 | 8eea81e090 | +------------------------------------------------+------------+------------+ | boot_successes | 0 | 0 | | boot_failures | 8 | 8 | | IP-Config:Auto-configuration_of_network_failed | 8 | | | BUG:unable_to_handle_kernel | 0 | 8 | | Oops | 0 | 8 | | EIP_is_at_remove_element | 0 | 8 | | calltrace:scsi_debug_init | 0 | 8 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 8 | +------------------------------------------------+------------+------------+ [ 4.082237] blk-mq: sq sched init failed [ 4.082967] scsi 0:0:0:0: Direct-Access Linux scsi_debug 0186 PQ: 0 ANSI: 7 [ 4.088634] scsi 0:0:0:0: Attached scsi generic sg0 type 0 [ 4.090968] BUG: unable to handle kernel paging request at f20bc5d2 [ 4.091900] IP: [<41177b90>] remove_element+0x1c/0x97 [ 4.092706] *pde = 00000000 [ 4.093139] Oops: 0000 [#1] SMP [ 4.093566] Modules linked in: [ 4.094013] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.9.0-rc1-00159-g8eea81e #1 [ 4.095017] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 4.096210] task: 40320000 task.stack: 4031a000 [ 4.096822] EIP: 0060:[<41177b90>] EFLAGS: 00210246 CPU: 0 [ 4.097566] EIP is at remove_element+0x1c/0x97 [ 4.098267] EAX: 303a303a EBX: 30746566 ECX: 00000000 EDX: 00000000 [ 4.099113] ESI: 4dbacba0 EDI: 4b624454 EBP: 4031bcd0 ESP: 4031bcc0 [ 4.100090] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 [ 4.100814] CR0: 80050033 CR2: f20bc5d2 CR3: 02325000 CR4: 000406d0 [ 4.101671] Stack: [ 4.101960] 00000000 4dbacba0 00000000 4b624454 4031bce0 41177c4e 4b624454 4b624000 [ 4.104688] 4031bce8 414218a6 4031bcf8 41426009 41f17760 00000000 4031bd10 41448e06 [ 4.105815] 00000000 00000001 4dbaac14 4b620000 4031bd1c 41448caa 4b6203d8 4031bd24 [ 4.106867] Call Trace: [ 4.107180] [<41177c4e>] mempool_destroy+0x43/0x5e [ 4.107821] [<414218a6>] blk_exit_rl+0x2a/0x2c [ 4.108459] [<41426009>] blk_release_queue+0x6a/0x10a [ 4.109184] [<41448e06>] kobject_release+0xb3/0xda [ 4.109854] [<41448caa>] kobject_put+0x8a/0x8f [ 4.110464] [<4141e46e>] blk_put_queue+0x12/0x14 [ 4.114154] [<415998ab>] scsi_device_dev_release_usercontext+0xb1/0x10c [ 4.115065] [<4196369b>] ? _raw_spin_lock_irqsave+0x40/0x49 [ 4.115843] [<415997fa>] ? scsi_device_dev_release+0x1a/0x1a [ 4.116607] [<41087993>] execute_in_process_context+0x35/0x87 [ 4.117394] [<415997f8>] scsi_device_dev_release+0x18/0x1a [ 4.118154] [<415467d8>] device_release+0x6e/0xd6 [ 4.118820] [<41448e06>] kobject_release+0xb3/0xda [ 4.119480] [<41448caa>] kobject_put+0x8a/0x8f [ 4.120100] [<415468f6>] put_device+0x2a/0x2c [ 4.120705] [<4159ab6b>] __scsi_remove_device+0x116/0x11a [ 4.121445] [<41598cff>] scsi_forget_host+0x5c/0x6b [ 4.122128] [<4158b9e1>] scsi_remove_host+0xa1/0x13e [ 4.122816] [<415c6c23>] sdebug_driver_remove+0x4b/0x87 [ 4.123539] [<4154b3c4>] driver_probe_device+0x274/0x457 [ 4.126619] [<4154b7ca>] __device_attach_driver+0xe9/0xf5 [ 4.127293] [<41549520>] bus_for_each_drv+0x8f/0x9c [ 4.127924] [<4154b0b4>] __device_attach+0xbc/0x117 [ 4.128610] [<4154b6e1>] ? driver_allows_async_probing+0x37/0x37 [ 4.129429] [<4154b963>] device_initial_probe+0x12/0x14 [ 4.130150] [<4154a5ec>] bus_probe_device+0x5b/0xb3 [ 4.130828] [<415484fd>] device_add+0x62d/0x7ac [ 4.131453] [<410c535f>] ? __raw_spin_lock_init+0x2b/0x4e [ 4.132207] [<41548693>] device_register+0x17/0x1a [ 4.132873] [<415ce07a>] sdebug_add_adapter+0x12a/0x189 [ 4.133590] [<4228ed72>] scsi_debug_init+0x868/0x8fc [ 4.134272] [<4144a67c>] ? kobject_uevent+0xa/0xc [ 4.134930] [<4154be67>] ? driver_register+0x14a/0x163 [ 4.135641] [<4159a0e3>] ? scsi_register_driver+0x14/0x16 [ 4.136388] [<4228e50a>] ? init_ch_module+0xfe/0xfe [ 4.137058] [<41000542>] do_one_initcall+0xa3/0x19d [ 4.137731] [<42241500>] ? do_early_param+0x8c/0xab [ 4.138407] [<4108f593>] ? parse_args+0x347/0x3f5 [ 4.139067] [<422420c1>] kernel_init_freeable+0x1a4/0x267 [ 4.139811] [<419550aa>] ? rest_init+0x134/0x134 [ 4.140448] [<419550b7>] kernel_init+0xd/0x15a [ 4.141067] [<4196370b>] ret_from_fork+0x1b/0x30 [ 4.141715] Code: 2c 8b 45 f0 ff 53 34 8d 65 f4 5b 5e 5f 5d c3 55 89 e5 57 56 53 51 3e 8d 74 26 00 89 c6 8b 40 28 8b 4e 24 8d 59 ff 31 c9 89 5e 24 <8b> 04 98 89 df c1 ef 1f 89 fa 89 45 f0 b8 54 d3 f6 41 e8 a3 37 [ 4.145368] EIP: [<41177b90>] [ 4.145771] remove_element+0x1c/0x97 [ 4.146361] SS:ESP 0068:4031bcc0 [ 4.146819] CR2: 00000000f20bc5d2 [ 4.147281] ---[ end trace 521bb1a6e38aae0f ]--- [ 4.147912] Kernel panic - not syncing: Fatal exception [ 4.148688] Kernel Offset: disabled Elapsed time: 20 To reproduce: git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git cd lkp-tests bin/lkp qemu -k <bzImage> job-script # job-script is attached in this email Thanks, Ying Huang