FYI, we noticed the following commit: commit: 0dc51b77973dcff6cc596b1547160e891504de4e ("Shrink rwsem by one pointer") git://git.infradead.org/users/willy/linux-dax.git waiter-diet in testcase: boot on test machine: qemu-system-x86_64 -enable-kvm -m 320M caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +--------------------------------------------------+------------+------------+ | | 1b1bc42c16 | 0dc51b7797 | +--------------------------------------------------+------------+------------+ | boot_successes | 6 | 0 | | boot_failures | 0 | 7 | | INFO:task_blocked_for_more_than#seconds | 0 | 7 | | Kernel_panic-not_syncing:hung_task:blocked_tasks | 0 | 7 | +--------------------------------------------------+------------+------------+ [ 242.897873] INFO: task swapper/0:1 blocked for more than 120 seconds. [ 242.901991] Not tainted 4.10.0-rc5-00368-g0dc51b7 #1 [ 242.902995] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 242.904392] swapper/0 D13200 1 0 0x00000000 [ 242.905486] Call Trace: [ 242.905949] __schedule+0x6f1/0x8b0 [ 242.906569] ? _raw_spin_unlock_irq+0x2c/0x50 [ 242.907335] schedule+0x28/0x40 [ 242.907899] ? rwsem_down_write_failed+0x36f/0x450 [ 242.908702] rwsem_down_write_failed+0x374/0x450 [ 242.909514] ? rwsem_down_write_failed+0x58/0x450 [ 242.910322] ? do_early_param+0x8f/0x8f [ 242.910974] call_rwsem_down_write_failed+0x17/0x30 [ 242.911773] down_write+0x5f/0x80 [ 242.912368] ? crypto_larval_kill+0x19/0x80 [ 242.913083] crypto_larval_kill+0x19/0x80 [ 242.913830] crypto_wait_for_test+0x65/0x80 [ 242.914565] crypto_register_alg+0x53/0x60 [ 242.915367] ? trace_event_define_fields_mpx_new_bounds_table+0x29/0x29 [ 242.916489] aes_init+0x10/0x12 [ 242.917057] do_one_initcall+0x9a/0x169 [ 242.917701] ? do_early_param+0x8f/0x8f [ 242.918394] kernel_init_freeable+0x1e0/0x26f [ 242.919146] ? rest_init+0x140/0x140 [ 242.919752] kernel_init+0xe/0xf0 [ 242.920343] ret_from_fork+0x31/0x40 [ 242.920956] [ 242.920956] Showing all locks held in the system: [ 242.922023] 1 lock held by swapper/0/1: [ 242.922676] #0: (crypto_alg_sem){+.+.+.}, at: [<ffffffff812cbb99>] crypto_larval_kill+0x19/0x80 [ 242.924232] 2 locks held by khungtaskd/16: [ 242.925094] #0: (rcu_read_lock){......}, at: [<ffffffff8115b4f1>] watchdog+0x91/0x5f0 [ 242.926412] #1: (tasklist_lock){.+.+..}, at: [<ffffffff8110deaa>] debug_show_all_locks+0x4a/0x170 [ 242.927780] [ 242.928053] ============================================= [ 242.928053] [ 242.929041] NMI backtrace for cpu 0 [ 242.929668] CPU: 0 PID: 16 Comm: khungtaskd Not tainted 4.10.0-rc5-00368-g0dc51b7 #1 [ 242.930812] Call Trace: [ 242.931207] dump_stack+0x86/0xc1 [ 242.931727] nmi_cpu_backtrace+0xde/0xf0 [ 242.932348] ? irq_force_complete_move+0x180/0x180 [ 242.933277] nmi_trigger_cpumask_backtrace+0xd4/0x170 [ 242.934090] arch_trigger_cpumask_backtrace+0x19/0x20 [ 242.934915] watchdog+0x45d/0x5f0 [ 242.935473] ? watchdog+0x91/0x5f0 [ 242.936033] kthread+0x125/0x130 [ 242.936542] ? hung_task_panic+0x20/0x20 [ 242.937543] ? __kthread_bind_mask+0x70/0x70 [ 242.938219] ret_from_fork+0x31/0x40 [ 242.938826] Kernel panic - not syncing: hung_task: blocked tasks [ 242.939753] CPU: 0 PID: 16 Comm: khungtaskd Not tainted 4.10.0-rc5-00368-g0dc51b7 #1 [ 242.940979] Call Trace: [ 242.941536] dump_stack+0x86/0xc1 [ 242.942071] panic+0xda/0x21e [ 242.942540] watchdog+0x469/0x5f0 [ 242.943068] ? watchdog+0x91/0x5f0 [ 242.943601] kthread+0x125/0x130 [ 242.944116] ? hung_task_panic+0x20/0x20 [ 242.944750] ? __kthread_bind_mask+0x70/0x70 [ 242.945448] ret_from_fork+0x31/0x40 [ 242.946291] Kernel Offset: disabled Elapsed time: 250 initrds=( /osimage/yocto/yocto-tiny-i386-2016-04-22.cgz /lkp/scheduled/vm-lkp-nhm-dp2-yocto-ia32-12/boot-1-yocto-tiny-i386-2016-04-22.cgz-0dc51b77973dcff6cc596b1547160e891504de4e-20170213-77446-geazk3-0.cgz /lkp/lkp/lkp-i386.cgz /osimage/deps/debian-x86_64-2016-08-31.cgz/run-ipconfig.i386_2016-09-03.cgz ) cat "${initrds[@]}" > /fs/sda1/initrd-vm-lkp-nhm-dp2-yocto-ia32-12 kvm=( qemu-system-x86_64 -enable-kvm -kernel /pkg/linux/x86_64-randconfig-u0-02112140/gcc-6/0dc51b77973dcff6cc596b1547160e891504de4e/vmlinuz-4.10.0-rc5-00368-g0dc51b7 -initrd /fs/sda1/initrd-vm-lkp-nhm-dp2-yocto-ia32-12 -m 320 -smp 1 -device e1000,netdev=net0 -netdev user,id=net0 -boot order=nc -no-reboot -watchdog i6300esb -watchdog-action debug -rtc base=localtime -pidfile /dev/shm/kboot/pid-vm-lkp-nhm-dp2-yocto-ia32-12 -serial file:/dev/shm/kboot/vm-lkp-nhm-dp2-yocto-ia32-12/serial -serial file:/dev/shm/kboot/vm-lkp-nhm-dp2-yocto-ia32-12/kmsg -daemonize -display none -monitor null ) append=( ip=::::vm-lkp-nhm-dp2-yocto-ia32-12::dhcp root=/dev/ram0 user=lkp job=/lkp/scheduled/vm-lkp-nhm-dp2-yocto-ia32-12/boot-1-yocto-tiny-i386-2016-04-22.cgz-0dc51b77973dcff6cc596b1547160e891504de4e-20170213-77446-geazk3-0.yaml 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, Kernel Test Robot