INFO: task syz-executor.0:2117 blocked for more than 140 seconds. Not tainted 4.9.171+ #49 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D24792 2117 1 0x00000004 ffff8801cef48000 ffff8801d189f900 ffff8801db621000 ffff8801d1380000 ffff8801db621018 ffff8801abe1fb28 ffffffff82801dde 0000000041b58ab3 ffffffff82e287b8 00ffffff811ffec0 ffff8801db6218f0 1ffff100357c3f54 Call Trace: [<00000000212c3338>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000827872f3>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<00000000e9cb609a>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<00000000e9cb609a>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<000000002e6ce8b7>] __lo_release drivers/block/loop.c:1642 [inline] [<000000002e6ce8b7>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 [<00000000b05c2990>] __blkdev_put+0x461/0x840 fs/block_dev.c:1606 [<00000000322e5bf9>] blkdev_put+0x88/0x560 fs/block_dev.c:1671 [<00000000f0b6fc9c>] blkdev_close+0x8b/0xb0 fs/block_dev.c:1678 [<00000000aefed44c>] __fput+0x274/0x720 fs/file_table.c:208 [<0000000097e6d1aa>] ____fput+0x16/0x20 fs/file_table.c:244 [<0000000081c6d718>] task_work_run+0x108/0x180 kernel/task_work.c:116 [<00000000c174b9d8>] tracehook_notify_resume include/linux/tracehook.h:191 [inline] [<00000000c174b9d8>] exit_to_usermode_loop+0x13b/0x160 arch/x86/entry/common.c:162 [<00000000cf26eb13>] prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] [<00000000cf26eb13>] syscall_return_slowpath arch/x86/entry/common.c:263 [inline] [<00000000cf26eb13>] do_syscall_64+0x3f7/0x570 arch/x86/entry/common.c:290 [<000000007a5081a8>] 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: [<00000000082ff6c5>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<00000000082ff6c5>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<000000009fdfb4a6>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336 2 locks held by getty/2027: #0: (&tty->ldisc_sem){++++++}, at: [<000000006fc62629>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<0000000035b4725b>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 3 locks held by syz-executor.0/2117: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003098138b>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<00000000475a600d>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 #2: (loop_ctl_mutex#2){+.+.+.}, at: [<000000002e6ce8b7>] __lo_release drivers/block/loop.c:1642 [inline] #2: (loop_ctl_mutex#2){+.+.+.}, at: [<000000002e6ce8b7>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 2 locks held by syz-executor.1/2124: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000abb09d7b>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000004d5fc3cb>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.2/2129: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003098138b>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<00000000475a600d>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 2 locks held by syz-executor.3/2133: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000abb09d7b>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000004d5fc3cb>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.5/3375: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<000000000bf2fc90>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 #1: (&bdev->bd_mutex){+.+.+.}, at: [<000000009e68cce7>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by blkid/3385: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000abb09d7b>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000004d5fc3cb>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by blkid/3386: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000abb09d7b>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 1 lock held by blkid/3388: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000abb09d7b>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.171+ #49 ffff8801d98d7cc8 ffffffff81b4fb61 0000000000000000 0000000000000000 0000000000000000 ffffffff81097501 dffffc0000000000 ffff8801d98d7d00 ffffffff81b5adfc 0000000000000000 0000000000000000 0000000000000000 Call Trace: [<000000003bcd40dc>] __dump_stack lib/dump_stack.c:15 [inline] [<000000003bcd40dc>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<000000003de23d2d>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000a3371f59>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000aad0a763>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<0000000056020b24>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<0000000056020b24>] check_hung_task kernel/hung_task.c:126 [inline] [<0000000056020b24>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<0000000056020b24>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000000e28d3dc>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000f62c375f>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 9525 Comm: syz-executor.1 Not tainted 4.9.171+ #49 task: 00000000c61946d9 task.stack: 00000000b2cf303d RIP: 0010:[] c [<0000000049a54647>] arch_local_save_flags arch/x86/include/asm/paravirt.h:763 [inline] RIP: 0010:[] c [<0000000049a54647>] arch_local_irq_save arch/x86/include/asm/paravirt.h:785 [inline] RIP: 0010:[] c [<0000000049a54647>] lock_is_held+0x55/0x140 kernel/locking/lockdep.c:3790 RSP: 0000:ffff8801ade77b08 EFLAGS: 00000046 RAX: 0000000000000000 RBX: ffff88016d78df00 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff81bb61ec RDI: ffff88016d78e7ac RBP: ffff8801ade77b28 R08: 0000000000000000 R09: ffff88016d78e7f8 R10: ffff88016d78e7d8 R11: 0000000000000001 R12: ffffffff830d4660 R13: ffff880193fdc500 R14: 0000000002280020 R15: 000000000000000b FS: 00007fa5cc005700(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000672bc7c01c65 CR3: 000000015b877000 CR4: 00000000001606b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: 0000000000000046c 0000000000000001c ffff88016d78df00c ffff880193fdc500c ffff8801ade77b38c ffffffff812448fec ffff8801ade77b78c ffffffff81102940c ffffffff811025f0c ffff88016d78df00c 000000000000000bc 0000000000000000c Call Trace: [<00000000d5c18b82>] rcu_read_lock_held kernel/rcu/update.c:297 [inline] [<00000000d5c18b82>] rcu_read_lock_held+0x9e/0xc0 kernel/rcu/update.c:289 [<00000000bc172504>] __sigqueue_alloc+0x350/0x410 kernel/signal.c:373 [<00000000f0f546d4>] __send_signal+0x1a5/0x1240 kernel/signal.c:1071 [<00000000231cf08a>] send_signal+0x49/0xc0 kernel/signal.c:1138 [<000000007fad7c42>] specific_send_sig_info kernel/signal.c:1183 [inline] [<000000007fad7c42>] force_sig_info+0x20a/0x310 kernel/signal.c:1231 [<00000000eba15a20>] force_sig_info_fault.constprop.0+0x17a/0x290 arch/x86/mm/fault.c:244 [<00000000ab66b8d8>] __bad_area_nosemaphore+0x196/0x280 arch/x86/mm/fault.c:899 [<00000000aefa9521>] __bad_area arch/x86/mm/fault.c:933 [inline] [<00000000aefa9521>] bad_area+0x69/0x80 arch/x86/mm/fault.c:940 [<00000000121a3273>] __do_page_fault+0x798/0xa60 arch/x86/mm/fault.c:1376 [<0000000059e8a833>] do_page_fault+0x28/0x30 arch/x86/mm/fault.c:1469 [<00000000cfa65e82>] page_fault+0x25/0x30 arch/x86/entry/entry_64.S:951 Code: cc1 cea c03 c0f cb6 c14 c02 c48 c89 cf8 c83 ce0 c07 c83 cc0 c03 c38 cd0 c7c c08 c84 cd2 c0f c85 cd4 c00 c00 c00 c8b c83 cac c08 c00 c00 c85 cc0 c0f c85 cb6 c00 c00 c00 c9c c<58> c0f c1f c44 c00 c00 c48 c89 cc3 cfa c66 c0f c1f c44 c00 c00 c65 c4c c8b c2c c25 c