INFO: task syz-executor.5:2074 blocked for more than 140 seconds. Not tainted 4.9.205-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D25336 2074 1 0x00000004 0000000000000087 ffff8801ce944740 0000000000000000 ffff8801db71ffc0 ffff8801da6b2f80 ffff8801db71ffd8 ffff8801b36276a8 ffffffff8280a6ae 0000000000000246 ffffffff831f2ae8 00ff8801ce944fe8 ffff8801db7208b0 Call Trace: [<00000000a0609b27>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000f0c4cd8b>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<0000000092590ee6>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<0000000092590ee6>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<0000000040047ecd>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 [<00000000b1cde2fd>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1424 [<0000000006d76375>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1579 [<00000000a4dbd7f4>] do_dentry_open+0x422/0xd20 fs/open.c:791 [<000000001b3c6cd8>] vfs_open+0x105/0x230 fs/open.c:904 [<00000000abc55fb0>] do_last fs/namei.c:3457 [inline] [<00000000abc55fb0>] path_openat+0xbf5/0x2f60 fs/namei.c:3581 [<0000000024a8a047>] do_filp_open+0x1a1/0x280 fs/namei.c:3615 [<00000000f39f63b8>] do_sys_open+0x2f0/0x610 fs/open.c:1097 [<000000006ed0e37a>] SYSC_open fs/open.c:1115 [inline] [<000000006ed0e37a>] SyS_open+0x2d/0x40 fs/open.c:1110 [<00000000828992c6>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<00000000316f3aa5>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Showing all locks held in the system: 2 locks held by khungtaskd/24: #0: (rcu_read_lock){......}, at: [<000000001a71fdb1>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<000000001a71fdb1>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<00000000c15e8efd>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 2 locks held by getty/2021: #0: (&tty->ldisc_sem){++++++}, at: [<000000005dd88613>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+...}, at: [<00000000277dc9b3>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.5/2074: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000040047ecd>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 1 lock held by syz-executor.3/2076: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000040047ecd>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.4/2079: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000040047ecd>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000000fd7f04b>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.1/2081: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000040047ecd>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000000fd7f04b>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.2/7651: #0: (loop_index_mutex){+.+.+.}, at: [<00000000364458d8>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<00000000b0ba772e>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1988 1 lock held by syz-executor.2/7674: #0: (loop_index_mutex){+.+.+.}, at: [<00000000364458d8>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 1 lock held by syz-executor.2/7677: #0: (loop_index_mutex){+.+.+.}, at: [<00000000364458d8>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 1 lock held by syz-executor.2/7678: #0: (loop_index_mutex){+.+.+.}, at: [<00000000364458d8>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 1 lock held by syz-executor.2/7679: #0: (loop_index_mutex){+.+.+.}, at: [<00000000364458d8>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 2 locks held by syz-executor.0/7663: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<00000000d0496548>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<000000000578d1eb>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by blkid/7662: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000040047ecd>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000000fd7f04b>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by blkid/7667: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000040047ecd>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000000fd7f04b>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by blkid/7673: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000040047ecd>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000000fd7f04b>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.205-syzkaller #0 ffff8801d98d7cc8 ffffffff81b55e6b 0000000000000001 0000000000000000 0000000000000001 ffffffff8109a001 dffffc0000000000 ffff8801d98d7d00 ffffffff81b6110c 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<00000000eddaeb44>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000eddaeb44>] dump_stack+0xcb/0x130 lib/dump_stack.c:56 [<00000000f1d2ce7a>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<0000000042f6dbf6>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000e5e5e8cd>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<000000007bc164ed>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<000000007bc164ed>] check_hung_task kernel/hung_task.c:126 [inline] [<000000007bc164ed>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<000000007bc164ed>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<00000000a579f705>] kthread+0x278/0x310 kernel/kthread.c:211 [<000000004d5dfc98>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 7695 Comm: init Not tainted 4.9.205-syzkaller #0 task: 00000000d4f202cb task.stack: 00000000daeb042d RIP: 0010:[] c [<0000000068154408>] io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:414 RSP: 0018:ffff8801c717f580 EFLAGS: 00000002 RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000 RDX: 00000000000003fd RSI: ffffffff81d75b61 RDI: ffffffff84b66d98 RBP: ffff8801c717f590 R08: ffffffff8403bac0 R09: ffffffff82a56c40 R10: ffffffff83c77e00 R11: 0000000000000001 R12: ffffffff84b66d60 R13: 0000000000000020 R14: fffffbfff096cdf3 R15: fffffbfff096cdb5 FS: 00007f58aa8167a0(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f58a9f29a30 CR3: 00000001d816e000 CR4: 00000000001606b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: ffffffff84b66d60c 000000000000270fc ffff8801c717f5e0c ffffffff81d77e04c ffff8801c717f618c ffffffff84b66da8c ffffffff84b66f9ac ffffffff841d5603c ffffffff84b66d60c 0000000000000020c dffffc0000000000c 0000000000000020c Call Trace: [<00000000085a5f49>] serial_in drivers/tty/serial/8250/8250.h:111 [inline] [<00000000085a5f49>] wait_for_xmitr+0x94/0x1e0 drivers/tty/serial/8250/8250_port.c:1997 [<0000000031317b8a>] serial8250_console_putchar+0x20/0x60 drivers/tty/serial/8250/8250_port.c:3103 [<0000000003c90cf9>] uart_console_write+0x56/0xe0 drivers/tty/serial/serial_core.c:1885 [<00000000d3b7a6f9>] serial8250_console_write+0x2fb/0x860 drivers/tty/serial/8250/8250_port.c:3169 [<000000005ee8e47f>] univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:594 [<00000000c6c5c02a>] call_console_drivers.isra.0.constprop.0+0x1ac/0x360 kernel/printk/printk.c:1552 [<00000000f84e38b5>] console_unlock+0x422/0xb40 kernel/printk/printk.c:2406 [<00000000119fa8a9>] console_device+0x97/0xc0 kernel/printk/printk.c:2514 [<0000000049c4387f>] tty_lookup_driver drivers/tty/tty_io.c:2018 [inline] [<0000000049c4387f>] tty_open_by_driver drivers/tty/tty_io.c:2063 [inline] [<0000000049c4387f>] tty_open+0x796/0xe10 drivers/tty/tty_io.c:2140 [<00000000384db650>] chrdev_open+0x230/0x630 fs/char_dev.c:398 [<00000000a4dbd7f4>] do_dentry_open+0x422/0xd20 fs/open.c:791 [<000000001b3c6cd8>] vfs_open+0x105/0x230 fs/open.c:904 [<00000000abc55fb0>] do_last fs/namei.c:3457 [inline] [<00000000abc55fb0>] path_openat+0xbf5/0x2f60 fs/namei.c:3581 [<0000000024a8a047>] do_filp_open+0x1a1/0x280 fs/namei.c:3615 [<00000000f39f63b8>] do_sys_open+0x2f0/0x610 fs/open.c:1097 [<000000006ed0e37a>] SYSC_open fs/open.c:1115 [inline] [<000000006ed0e37a>] SyS_open+0x2d/0x40 fs/open.c:1110 [<00000000828992c6>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<00000000316f3aa5>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Code: c24 cc9 c00 c00 c00 c49 c8d c7c c24 c38 c48 cb8 c00 c00 c00 c00 c00 cfc cff cdf c48 c89 cfa c48 cc1 cea c03 cd3 ce3 c80 c3c c02 c00 c75 c17 c41 c03 c5c c24 c38 c89 cda cec c<5b> c0f cb6 cc0 c41 c5c c5d cc3 ce8 cd8 c8a c78 cff ceb cc2 ce8 c31 c8b c78 cff ceb c