Buffer I/O error on dev loop1, logical block 0, async page read INFO: task syz-executor6:16392 blocked for more than 120 seconds. Not tainted 4.14.0+ #100 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor6 D23448 16392 3311 0x20020004 Call Trace: context_switch kernel/sched/core.c:2799 [inline] __schedule+0x8eb/0x2060 kernel/sched/core.c:3375 schedule+0xf5/0x430 kernel/sched/core.c:3434 io_schedule+0x1c/0x70 kernel/sched/core.c:5042 wait_on_page_bit_common mm/filemap.c:1100 [inline] __lock_page+0x585/0x740 mm/filemap.c:1273 lock_page include/linux/pagemap.h:483 [inline] pagecache_get_page+0x672/0xba0 mm/filemap.c:1554 grab_cache_page_write_begin+0x6c/0xa0 mm/filemap.c:3089 block_write_begin+0xa6/0x2e0 fs/buffer.c:2092 blkdev_write_begin+0x3c/0x50 fs/block_dev.c:584 generic_perform_write+0x28f/0x600 mm/filemap.c:3139 __generic_file_write_iter+0x366/0x5b0 mm/filemap.c:3264 blkdev_write_iter+0x207/0x3e0 fs/block_dev.c:1893 call_write_iter include/linux/fs.h:1772 [inline] do_iter_readv_writev+0x531/0x7f0 fs/read_write.c:653 do_iter_write+0x15a/0x540 fs/read_write.c:932 vfs_iter_write+0x77/0xb0 fs/read_write.c:945 iter_file_splice_write+0x7db/0xf30 fs/splice.c:749 do_splice_from fs/splice.c:851 [inline] direct_splice_actor+0x125/0x180 fs/splice.c:1018 splice_direct_to_actor+0x2c1/0x820 fs/splice.c:973 do_splice_direct+0x2a7/0x3d0 fs/splice.c:1061 do_sendfile+0x5d5/0xe90 fs/read_write.c:1413 C_SYSC_sendfile fs/read_write.c:1489 [inline] compat_SyS_sendfile+0xea/0x1a0 fs/read_write.c:1478 do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline] do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389 entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:125 RIP: 0023:0xf7fc2c79 RSP: 002b:00000000f779d01c EFLAGS: 00000296 ORIG_RAX: 00000000000000bb RAX: ffffffffffffffda RBX: 0000000000000019 RCX: 000000000000001a RDX: 0000000020f92ff8 RSI: 00000000fffffffe RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 3 locks held by kworker/u4:1/21: #0: ((wq_completion)"writeback"){+.+.}, at: [] __write_once_size include/linux/compiler.h:207 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [] atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [] atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [] set_work_data kernel/workqueue.c:618 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:645 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [] process_one_work+0xad4/0x1be0 kernel/workqueue.c:2083 #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [] process_one_work+0xb2f/0x1be0 kernel/workqueue.c:2087 #2: (&type->s_umount_key#31){.+.+}, at: [] trylock_super+0x20/0x100 fs/super.c:396 2 locks held by khungtaskd/668: #0: (rcu_read_lock){....}, at: [] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4554 2 locks held by getty/3017: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3018: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3019: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3020: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3021: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3022: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3023: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 1 lock held by blkid/16387: #0: (&bdev->bd_mutex){+.+.}, at: [] blkdev_put+0x2a/0x4f0 fs/block_dev.c:1793 1 lock held by syz-executor0/16400: #0: (&bdev->bd_mutex){+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2145 1 lock held by syz-executor0/16407: #0: (&bdev->bd_mutex){+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2145 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 668 Comm: khungtaskd Not tainted 4.14.0+ #100 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x122/0x180 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline] check_hung_task kernel/hung_task.c:132 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline] watchdog+0x90c/0xd60 kernel/hung_task.c:249 kthread+0x37a/0x440 kernel/kthread.c:238 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:437 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54