INFO: task syz-executor0:8210 blocked for more than 120 seconds. Not tainted 4.17.0-rc6+ #68 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor0 D23672 8210 4459 0x00000004 Call Trace: context_switch kernel/sched/core.c:2859 [inline] __schedule+0x801/0x1e30 kernel/sched/core.c:3501 schedule+0xef/0x430 kernel/sched/core.c:3545 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3603 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xe38/0x17f0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 __fdget_pos+0x1a9/0x1e0 fs/file.c:766 fdget_pos include/linux/file.h:67 [inline] ksys_write+0x77/0x250 fs/read_write.c:593 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x455a09 RSP: 002b:00007f0b00977c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f0b009786d4 RCX: 0000000000455a09 RDX: 0000000000000801 RSI: 0000000020000280 RDI: 0000000000000013 RBP: 000000000072bf50 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000780 R14: 00000000006ff4a0 R15: 0000000000000001 Showing all locks held in the system: 2 locks held by kworker/u4:1/22: #0: 00000000f8af561d ((wq_completion)"writeback"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 00000000f8af561d ((wq_completion)"writeback"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000f8af561d ((wq_completion)"writeback"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000f8af561d ((wq_completion)"writeback"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 00000000f8af561d ((wq_completion)"writeback"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 00000000f8af561d ((wq_completion)"writeback"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 00000000f8af561d ((wq_completion)"writeback"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: 000000004f017173 ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 2 locks held by khungtaskd/892: #0: 00000000f44c2e11 (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000f44c2e11 (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 00000000481a6cf1 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by getty/4386: #0: 0000000026062d2b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000064593f78 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4387: #0: 00000000ff7ce6bd (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000576d5e0c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4388: #0: 00000000812b4308 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000f9cddd52 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4389: #0: 000000004343d8c2 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000a144f4e1 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4390: #0: 000000000d382667 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000008363c63b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4391: #0: 000000009431eec4 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000286270ce (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4392: #0: 00000000be6bfbe8 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000038ae735f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 1 lock held by syz-executor0/8210: #0: 000000002d5167b8 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1a9/0x1e0 fs/file.c:766 1 lock held by syz-executor0/8212: #0: 000000002d5167b8 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1a9/0x1e0 fs/file.c:766 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 892 Comm: khungtaskd Not tainted 4.17.0-rc6+ #68 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x151/0x192 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+0xc10/0xf60 kernel/hung_task.c:249 kthread+0x345/0x410 kernel/kthread.c:240 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 8144 Comm: syz-executor0 Not tainted 4.17.0-rc6+ #68 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:lookup_bh_lru fs/buffer.c:1256 [inline] RIP: 0010:__find_get_block+0x18c/0xe50 fs/buffer.c:1283 RSP: 0018:ffff8801b724ef38 EFLAGS: 00000046 RAX: 0000000000040000 RBX: ffff8801bab4adc8 RCX: ffffc90001ed0000 RDX: 0000000000040000 RSI: ffffffff81cfe58c RDI: 0000000000000005 RBP: ffff8801b724f0c8 R08: ffff8801b6cc6100 R09: fffff94000c0ed13 R10: fffff94000c0ed13 R11: ffffea000607689f R12: 0000000000000008 R13: dffffc0000000000 R14: 0000000000000008 R15: 00000000000301af FS: 00007f0b00999700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000001b44a9000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __getblk_slow fs/buffer.c:1032 [inline] __getblk_gfp+0x2a1/0xaf0 fs/buffer.c:1313 __bread_gfp+0x2d/0x310 fs/buffer.c:1347 sb_bread include/linux/buffer_head.h:309 [inline] __fat_write_inode+0x33f/0xb40 fs/fat/inode.c:845 fat_write_inode+0x97/0x180 fs/fat/inode.c:894 write_inode fs/fs-writeback.c:1183 [inline] __writeback_single_inode+0xf18/0x15c0 fs/fs-writeback.c:1382 writeback_single_inode+0x364/0x510 fs/fs-writeback.c:1436 sync_inode fs/fs-writeback.c:2470 [inline] sync_inode_metadata+0x10b/0x160 fs/fs-writeback.c:2490 __generic_file_fsync+0x16f/0x200 fs/libfs.c:988 generic_file_fsync+0x77/0x120 fs/libfs.c:1018 fat_file_fsync+0x77/0x180 fs/fat/file.c:165 vfs_fsync_range+0x140/0x220 fs/sync.c:197 generic_write_sync include/linux/fs.h:2689 [inline] generic_file_write_iter+0x5f1/0x850 mm/filemap.c:3296 call_write_iter include/linux/fs.h:1784 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x64d/0x960 fs/read_write.c:487 vfs_write+0x1f8/0x560 fs/read_write.c:549 ksys_write+0xf9/0x250 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x455a09 RSP: 002b:00007f0b00998c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f0b009996d4 RCX: 0000000000455a09 RDX: 00000000ffffff43 RSI: 0000000020000180 RDI: 0000000000000013 RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000784 R14: 00000000006ff500 R15: 0000000000000000 Code: 0f 84 44 01 00 00 e8 74 5b a9 ff 45 89 e6 48 c7 c0 a0 90 02 00 65 4a 8b 1c f0 48 89 9d 90 fe ff ff 48 85 db 74 c0 e8 54 5b a9 ff <48> 8d 7b 18 48 89 f8 48 c1 e8 03 42 80 3c 28 00 0f 85 fe 0a 00 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.006 msecs