INFO: task syz-executor0:19869 blocked for more than 140 seconds. Not tainted 4.19.0-next-20181031+ #102 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor0 D19736 19869 5750 0x80000006 Call Trace: context_switch kernel/sched/core.c:2831 [inline] __schedule+0x8cf/0x21d0 kernel/sched/core.c:3472 schedule+0xfe/0x460 kernel/sched/core.c:3516 __rwsem_down_write_failed_common+0xc9a/0x15e0 kernel/locking/rwsem-xadd.c:577 rwsem_down_write_failed+0xe/0x10 kernel/locking/rwsem-xadd.c:606 call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:117 __down_write arch/x86/include/asm/rwsem.h:142 [inline] down_write+0xa5/0x130 kernel/locking/rwsem.c:72 deactivate_super+0x2b3/0x320 fs/super.c:358 cleanup_mnt+0xbf/0x160 fs/namespace.c:1049 __cleanup_mnt+0x16/0x20 fs/namespace.c:1056 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x1ad1/0x26d0 kernel/exit.c:867 do_group_exit+0x177/0x440 kernel/exit.c:970 get_signal+0x8a8/0x1970 kernel/signal.c:2517 do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816 exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457569 Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f758dc42cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000072bf08 RCX: 0000000000457569 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000072bf08 RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000072bf0c R13: 00007fff04b8bc6f R14: 00007f758dc439c0 R15: 0000000000000000 Showing all locks held in the system: 3 locks held by kworker/u4:4/285: 1 lock held by khungtaskd/1009: #0: 00000000416c8c1c (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x424 kernel/locking/lockdep.c:4379 1 lock held by rsyslogd/5538: #0: 0000000030b1e0c2 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 2 locks held by getty/5629: #0: 00000000e2539c8a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000037deff9a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5630: #0: 00000000684ce06d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000009b330456 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5631: #0: 000000000cb2e036 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000c0feb34e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5632: #0: 00000000683dc058 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000603e59bb (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5633: #0: 00000000b879bb60 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000044160ea3 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5634: #0: 000000005be698db (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000ae079052 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5635: #0: 000000009156a5b4 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000219cf52e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 1 lock held by syz-executor0/19869: #0: 00000000205f2dfa (&fc->fs_type->s_umount_key#49){++++}, at: deactivate_super+0x2b3/0x320 fs/super.c:358 2 locks held by syz-executor0/23957: #0: 00000000064d3648 (br_ioctl_mutex){+.+.}, at: sock_ioctl+0x2b5/0x690 net/socket.c:1040 #1: 000000002aabcc4a (rtnl_mutex){+.+.}, at: rtnl_lock+0x17/0x20 net/core/rtnetlink.c:77 1 lock held by syz-executor0/23958: #0: 00000000064d3648 (br_ioctl_mutex){+.+.}, at: sock_ioctl+0x2b5/0x690 net/socket.c:1040 1 lock held by syz-executor3/23962: #0: 00000000064d3648 (br_ioctl_mutex){+.+.}, at: sock_ioctl+0x2b5/0x690 net/socket.c:1040 1 lock held by syz-executor3/23963: #0: 00000000064d3648 (br_ioctl_mutex){+.+.}, at: sock_ioctl+0x2b5/0x690 net/socket.c:1040 1 lock held by syz-executor5/23967: #0: 00000000064d3648 (br_ioctl_mutex){+.+.}, at: sock_ioctl+0x2b5/0x690 net/socket.c:1040 1 lock held by syz-executor5/23968: #0: 00000000064d3648 (br_ioctl_mutex){+.+.}, at: sock_ioctl+0x2b5/0x690 net/socket.c:1040 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1009 Comm: khungtaskd Not tainted 4.19.0-next-20181031+ #102 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+0x244/0x39d lib/dump_stack.c:113 nmi_cpu_backtrace.cold.2+0x5c/0xa1 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1e8/0x22a 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:144 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xb4c/0x1060 kernel/hung_task.c:289 kthread+0x35a/0x440 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 0 to CPUs 1: INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 2.417 msecs NMI backtrace for cpu 1 CPU: 1 PID: 285 Comm: kworker/u4:4 Not tainted 4.19.0-next-20181031+ #102 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: writeback wb_workfn (flush-7:0) RIP: 0010:rcu_dynticks_curr_cpu_in_eqs+0x10d/0x170 kernel/rcu/tree.c:289 Code: e9 03 0f b6 14 11 84 d2 74 05 80 fa 03 7e 3a 48 ba 00 00 00 00 00 fc ff df 41 89 45 c0 d1 e8 83 f0 01 48 c7 04 13 00 00 00 00 <83> e0 01 48 8b 75 d8 65 48 33 34 25 28 00 00 00 75 45 48 83 c4 68 RSP: 0018:ffff8801d96edbd8 EFLAGS: 00000202 RAX: 00000000000515d0 RBX: 1ffff1003b2ddb7c RCX: 1ffff1003b2ddb80 RDX: dffffc0000000000 RSI: 0000000000000004 RDI: ffff8801d96edc00 RBP: ffff8801d96edc60 R08: ffffed003b5e5b68 R09: ffffed003b5e5b67 R10: ffffed003b5e5b67 R11: ffff8801daf2db3b R12: ffff8801daf2da80 R13: ffff8801d96edc40 R14: ffff8801daf2db38 R15: 1ffff1003b2ddc8d FS: 0000000000000000(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f4500e49000 CR3: 00000001bc2e5000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_is_watching+0x10/0x30 kernel/rcu/tree.c:906 rcu_read_lock include/linux/rcupdate.h:608 [inline] find_get_entry+0xce5/0x1120 mm/filemap.c:1412 pagecache_get_page+0x12f/0xf00 mm/filemap.c:1518 find_or_create_page include/linux/pagemap.h:322 [inline] grow_dev_page fs/buffer.c:947 [inline] grow_buffers fs/buffer.c:1029 [inline] __getblk_slow fs/buffer.c:1062 [inline] __getblk_gfp+0x4ca/0x1030 fs/buffer.c:1351 __bread_gfp+0x2d/0x310 fs/buffer.c:1385 sb_bread include/linux/buffer_head.h:307 [inline] __fat_write_inode+0x347/0xb60 fs/fat/inode.c:860 fat_write_inode+0x97/0x180 fs/fat/inode.c:909 write_inode fs/fs-writeback.c:1176 [inline] __writeback_single_inode+0xf4a/0x1650 fs/fs-writeback.c:1375 writeback_sb_inodes+0x71f/0x1210 fs/fs-writeback.c:1580 __writeback_inodes_wb+0x1b9/0x340 fs/fs-writeback.c:1649 wb_writeback+0xa64/0xfb0 fs/fs-writeback.c:1758 wb_check_old_data_flush fs/fs-writeback.c:1860 [inline] wb_do_writeback fs/fs-writeback.c:1913 [inline] wb_workfn+0xffe/0x1780 fs/fs-writeback.c:1942 process_one_work+0xc8b/0x1c40 kernel/workqueue.c:2153 worker_thread+0x17f/0x1390 kernel/workqueue.c:2296 kthread+0x35a/0x440 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 kobject: 'rx-0' (00000000ad616c33): kobject_cleanup, parent 000000001f901462 kobject: 'loop2' (00000000a618d19c): kobject_uevent_env kobject: 'rx-0' (00000000ad616c33): auto cleanup 'remove' event kobject: 'loop2' (00000000a618d19c): fill_kobj_path: path = '/devices/virtual/block/loop2' kobject: 'rx-0' (00000000ad616c33): kobject_uevent_env