Buffer I/O error on dev loop0, logical block 0, lost async page write INFO: task syz-executor4:5324 blocked for more than 120 seconds. Not tainted 4.15.0-rc9+ #278 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor4 D22304 5324 18284 0x00000004 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+0x574/0x720 mm/filemap.c:1273 lock_page include/linux/pagemap.h:483 [inline] write_cache_pages+0xb2b/0x14a0 mm/page-writeback.c:2206 generic_writepages+0xe9/0x150 mm/page-writeback.c:2325 blkdev_writepages+0x1d/0x30 fs/block_dev.c:1939 do_writepages+0xff/0x170 mm/page-writeback.c:2340 __filemap_fdatawrite_range+0x32f/0x460 mm/filemap.c:445 file_write_and_wait_range+0x8a/0x100 mm/filemap.c:753 blkdev_fsync+0x67/0xb0 fs/block_dev.c:623 vfs_fsync_range+0x110/0x260 fs/sync.c:196 generic_write_sync include/linux/fs.h:2685 [inline] blkdev_write_iter+0x2e6/0x3e0 fs/block_dev.c:1895 call_write_iter include/linux/fs.h:1772 [inline] do_iter_readv_writev+0x525/0x7f0 fs/read_write.c:653 do_iter_write+0x154/0x540 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+0x29b/0x3c0 fs/splice.c:1061 do_sendfile+0x5c9/0xe80 fs/read_write.c:1413 SYSC_sendfile64 fs/read_write.c:1468 [inline] SyS_sendfile64+0xbd/0x160 fs/read_write.c:1460 entry_SYSCALL_64_fastpath+0x29/0xa0 RIP: 0033:0x452f19 RSP: 002b:00007fa81c381c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452f19 RDX: 00000000200ddff8 RSI: 0000000000000016 RDI: 0000000000000015 RBP: 00000000000003cb R08: 0000000000000000 R09: 0000000000000000 R10: 0000000100000001 R11: 0000000000000212 R12: 00000000006f4ba8 R13: 00000000ffffffff R14: 00007fa81c3826d4 R15: 0000000000000000 Showing all locks held in the system: 3 locks held by kworker/u4:2/37: #0: ((wq_completion)"writeback"){+.+.}, at: [<000000004066eea8>] process_one_work+0xaaf/0x1b10 kernel/workqueue.c:2084 #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [<000000005f4ea1e7>] process_one_work+0xb01/0x1b10 kernel/workqueue.c:2088 #2: (&type->s_umount_key#27){.+.+}, at: [<000000002d02127f>] trylock_super+0x20/0x100 fs/super.c:395 2 locks held by khungtaskd/747: #0: (rcu_read_lock){....}, at: [<000000008df30969>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<000000008df30969>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<00000000039ee480>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4464 2 locks held by getty/3631: #0: (&tty->ldisc_sem){++++}, at: [<00000000411128b2>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000019a767d9>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3632: #0: (&tty->ldisc_sem){++++}, at: [<00000000411128b2>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000019a767d9>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3633: #0: (&tty->ldisc_sem){++++}, at: [<00000000411128b2>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000019a767d9>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3634: #0: (&tty->ldisc_sem){++++}, at: [<00000000411128b2>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000019a767d9>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3635: #0: (&tty->ldisc_sem){++++}, at: [<00000000411128b2>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000019a767d9>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3636: #0: (&tty->ldisc_sem){++++}, at: [<00000000411128b2>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000019a767d9>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/26547: #0: (&tty->ldisc_sem){++++}, at: [<00000000411128b2>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000019a767d9>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 1 lock held by syz-executor4/5358: #0: (&bdev->bd_mutex){+.+.}, at: [<0000000068f375d9>] __blkdev_get+0x158/0x10e0 fs/block_dev.c:1439 1 lock held by syz-executor0/5332: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000a56134a7>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2145 1 lock held by blkid/5351: #0: (&bdev->bd_mutex){+.+.}, at: [<0000000068f375d9>] __blkdev_get+0x158/0x10e0 fs/block_dev.c:1439 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 747 Comm: khungtaskd Not tainted 4.15.0-rc9+ #278 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+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:541 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