FYI, we noticed the following commit: https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git blk-dio commit 9f9093afaff2c4d247e5bc7d25ec0574e3f8d12b ("blk-mq: private O_DIRECT implementation") in testcase: boot on test machine: 2 threads qemu-system-x86_64 -enable-kvm -cpu Haswell,+smep,+smap with 2G memory caused below changes: +-------------------------------------------------------+------------+------------+ | | 0e06f5c0de | 9f9093afaf | +-------------------------------------------------------+------------+------------+ | boot_successes | 136 | 62 | | boot_failures | 0 | 73 | | BUG:unable_to_handle_kernel | 0 | 49 | | Oops | 0 | 49 | | RIP:blk_update_request | 0 | 32 | | Kernel_panic-not_syncing:Fatal_exception_in_interrupt | 0 | 73 | | RIP:__blk_recalc_rq_segments | 0 | 19 | | backtrace:vfs_read | 0 | 16 | | backtrace:SyS_read | 0 | 16 | | backtrace:vfs_llseek | 0 | 2 | | backtrace:SyS_lseek | 0 | 4 | | kernel_BUG_at_block/blk-mq.c | 0 | 22 | | invalid_opcode:#[##]SMP | 0 | 22 | | RIP:blk_mq_end_request | 0 | 22 | | general_protection_fault:#[##]SMP | 0 | 2 | | backtrace:SyS_newfstat | 0 | 2 | | backtrace:SyS_ioctl | 0 | 3 | +-------------------------------------------------------+------------+------------+ Starting Copy rules generated while the root was ro... Starting LSB: MD array assembly... [ 11.626304] ------------[ cut here ]------------ [ 11.628118] kernel BUG at block/blk-mq.c:365! [ 11.632175] invalid opcode: 0000 [#1] SMP [ 11.637668] Modules linked in: [ 11.639205] CPU: 0 PID: 2175 Comm: mdadm Not tainted 4.7.0-03200-g9f9093a #1 [ 11.643243] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 11.650426] task: ffff88007eae0dc0 ti: ffff88007f814000 task.ti: ffff88007f814000 [ 11.655392] RIP: 0010:[] [] blk_mq_end_request+0x1e/0x5c [ 11.665009] RSP: 0000:ffff880078803f20 EFLAGS: 00010002 [ 11.666863] RAX: 0000000000000001 RBX: ffff88007fab0000 RCX: 0000000000000000 [ 11.672882] RDX: ffff88007f7b6000 RSI: 0000000000000000 RDI: 0000000000000000 [ 11.674849] RBP: ffff880078803f30 R08: ffff88005c2d6e18 R09: 0000000000000000 [ 11.683957] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 11.685930] R13: ffff88007fab0000 R14: ffffffff81ea9f36 R15: 0000000000000000 [ 11.687896] FS: 00007f2286125700(0000) GS:ffff880078800000(0000) knlGS:0000000000000000 [ 11.690695] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 11.712461] CR2: 0000000001623d88 CR3: 000000007eca6000 CR4: 00000000000406f0 [ 11.714451] Stack: [ 11.715542] ffff88007fab0010 ffffffff814c9b0e ffff880078803f40 ffffffff815cc751 [ 11.718637] ffff880078803f50 ffffffff814c9b21 ffff880078803f88 ffffffff8116c346 [ 11.739752] 0000000000000000 0000000000000000 0000000000000001 0000000000000001 [ 11.742821] Call Trace: [ 11.743980] [ 11.744418] [] ? __blk_mq_end_request+0x44/0x44 [ 11.746998] [] virtblk_request_done+0x5e/0x60 [ 11.748775] [] __blk_mq_complete_request_remote+0x13/0x15 [ 11.750755] [] flush_smp_call_function_queue+0xcd/0x13e [ 11.765696] [] generic_smp_call_function_single_interrupt+0x13/0x4a [ 11.768446] [] smp_call_function_single_interrupt+0x27/0x35 [ 11.771070] [] call_function_single_interrupt+0x8c/0xa0 [ 11.772982] [ 11.773415] Code: 48 83 c4 28 5b 41 5c 41 5d 41 5e 5d c3 0f 1f 44 00 00 55 48 89 e5 41 54 53 8b 57 58 48 89 fb 41 89 f4 e8 cc 7c ff ff 84 c0 74 02 <0f> 0b 48 89 df e8 cd 7f ff ff 48 8b 83 98 01 00 00 48 85 c0 74 [ 11.799220] RIP [] blk_mq_end_request+0x1e/0x5c [ 11.801131] RSP [ 11.802469] ---[ end trace 58ac7b630a6d0c87 ]--- [ 11.804084] Kernel panic - not syncing: Fatal exception in interrupt FYI, raw QEMU command line is: qemu-system-x86_64 -enable-kvm -cpu Haswell,+smep,+smap -kernel /pkg/linux/x86_64-lkp/gcc-6/9f9093afaff2c4d247e5bc7d25ec0574e3f8d12b/vmlinuz-4.7.0-03200-g9f9093a -append 'ip=::::vm-kbuild-2G-3::dhcp root=/dev/ram0 user=lkp job=/lkp/scheduled/vm-kbuild-2G-3/boot-1-debian-x86_64-2015-02-07.cgz-9f9093afaff2c4d247e5bc7d25ec0574e3f8d12b-20160731-116574-1tj3h35-63.yaml ARCH=x86_64 kconfig=x86_64-lkp branch=linux-devel/devel-hourly-2016073021 commit=9f9093afaff2c4d247e5bc7d25ec0574e3f8d12b BOOT_IMAGE=/pkg/linux/x86_64-lkp/gcc-6/9f9093afaff2c4d247e5bc7d25ec0574e3f8d12b/vmlinuz-4.7.0-03200-g9f9093a max_uptime=600 RESULT_ROOT=/result/boot/1/vm-kbuild-2G/debian-x86_64-2015-02-07.cgz/x86_64-lkp/gcc-6/9f9093afaff2c4d247e5bc7d25ec0574e3f8d12b/63 LKP_SERVER=inn debug apic=debug sysrq_always_enabled rcupdate.rcu_cpu_stall_timeout=100 panic=-1 softlockup_panic=1 nmi_watchdog=panic oops=panic load_ramdisk=2 prompt_ramdisk=0 systemd.log_level=err ignore_loglevel earlyprintk=ttyS0,115200 console=ttyS0,115200 console=tty0 vga=normal rw' -initrd /fs/sdc1/initrd-vm-kbuild-2G-3 -m 2048 -smp 2 -device e1000,netdev=net0 -netdev user,id=net0,hostfwd=tcp::23018-:22 -boot order=nc -no-reboot -watchdog i6300esb -watchdog-action debug -rtc base=localtime -drive file=/fs/sdc1/disk0-vm-kbuild-2G-3,media=disk,if=virtio -drive file=/fs/sdc1/disk1-vm-kbuild-2G-3,media=disk,if=virtio -drive file=/fs/sdc1/disk2-vm-kbuild-2G-3,media=disk,if=virtio -drive file=/fs/sdc1/disk3-vm-kbuild-2G-3,media=disk,if=virtio -drive file=/fs/sdc1/disk4-vm-kbuild-2G-3,media=disk,if=virtio -drive file=/fs/sdc1/disk5-vm-kbuild-2G-3,media=disk,if=virtio -drive file=/fs/sdc1/disk6-vm-kbuild-2G-3,media=disk,if=virtio -pidfile /dev/shm/kboot/pid-vm-kbuild-2G-3 -serial file:/dev/shm/kboot/serial-vm-kbuild-2G-3 -daemonize -display none -monitor null Thanks, Xiaolong