INFO: task syz-executor.5:2122 blocked for more than 140 seconds. Not tainted 4.9.168+ #40 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D25528 2122 1 0x00000004 ffff8801d7780000 0000000000000000 ffff8801db721000 ffff8801da6b2f80 ffff8801db721018 ffff8801ae2d7988 ffffffff8280028e ffffffff8280fe2a 0000000000000000 00ffffff84341348 ffff8801db7218f0 1ffff10035c5af20 Call Trace: [<000000001cb0af11>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000cf0a74c2>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<00000000cc962b4b>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<00000000cc962b4b>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<0000000094c43911>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 [<000000004bbf696e>] loop_reread_partitions+0x7c/0x90 drivers/block/loop.c:638 [<00000000ecb2c653>] loop_clr_fd+0x7dd/0xa60 drivers/block/loop.c:1082 [<000000001a7b1bbc>] lo_ioctl+0x7b6/0x1a10 drivers/block/loop.c:1415 [<000000002248942e>] __blkdev_driver_ioctl block/ioctl.c:294 [inline] [<000000002248942e>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590 [<00000000aa5ec25c>] block_ioctl+0xde/0x120 fs/block_dev.c:1696 [<000000004438fb3d>] vfs_ioctl fs/ioctl.c:43 [inline] [<000000004438fb3d>] file_ioctl fs/ioctl.c:493 [inline] [<000000004438fb3d>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677 [<00000000bdd8efa4>] SYSC_ioctl fs/ioctl.c:694 [inline] [<00000000bdd8efa4>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [<00000000db16961e>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 [<0000000025ebf8ec>] 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: [<000000009a59afa4>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline] #0: (rcu_read_lock){......}, at: [<000000009a59afa4>] watchdog+0x13c/0xae0 kernel/hung_task.c:239 #1: (tasklist_lock){.+.+..}, at: [<000000004b849929>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 2 locks held by getty/2035: #0: (&tty->ldisc_sem){++++++}, at: [<00000000cd3d7eed>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<00000000c47676dd>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.5/2122: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000a3f62101>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 #1: (&bdev->bd_mutex){+.+.+.}, at: [<0000000094c43911>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 1 lock held by syz-executor.0/2132: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000a3f62101>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 1 lock held by syz-executor.1/2135: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000a3f62101>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 1 lock held by syz-executor.2/2140: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000a3f62101>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 1 lock held by syz-executor.4/2150: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000a3f62101>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 3 locks held by syz-executor.3/3081: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000fa657944>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<00000000de9b6a0c>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 #2: (loop_ctl_mutex#2){+.+...}, at: [<0000000087032264>] __lo_release drivers/block/loop.c:1642 [inline] #2: (loop_ctl_mutex#2){+.+...}, at: [<0000000087032264>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 1 lock held by blkid/3106: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000007dccfd9e>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by blkid/3107: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000007dccfd9e>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000d5e44cfc>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by syz-executor.3/3109: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000007dccfd9e>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.168+ #40 ffff8801d98d7cc8 ffffffff81b4f5d1 0000000000000001 0000000000000000 0000000000000001 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00 ffffffff81b5a86c 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<00000000f842a008>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000f842a008>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<0000000039eb1806>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000c77f8d6e>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000b9730c08>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<00000000f205218e>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<00000000f205218e>] check_hung_task kernel/hung_task.c:125 [inline] [<00000000f205218e>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [<00000000f205218e>] watchdog+0x661/0xae0 kernel/hung_task.c:239 [<00000000c28a361f>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000ed7731a3>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 2393 Comm: kworker/0:2 Not tainted 4.9.168+ #40 Workqueue: events_power_efficient gc_workerc task: 000000002b9b7490 task.stack: 0000000086bd1e3f RIP: 0010:[] c [<0000000017edba33>] get_current arch/x86/include/asm/current.h:14 [inline] RIP: 0010:[] c [<0000000017edba33>] __rcu_read_unlock+0x11/0x1a0 kernel/rcu/update.c:216 RSP: 0018:ffff8801c6c47b50 EFLAGS: 00000293 RAX: dffffc0000000000 RBX: dffffc0000000000 RCX: 1ffffffff05d1680 RDX: 0000000000000000 RSI: ffffffff82401cd4 RDI: ffffffff82e8b400 RBP: ffff8801c6c47b60 R08: 0000000000000001 R09: ffff8801c97188f8 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: fffffbfff0601200 R14: ffffffffffffffb8 R15: 000000000000fe63 FS: 0000000000000000(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000d10000 CR3: 00000001d4d23000 CR4: 00000000001606b0 Stack: dffffc0000000000c 0000000000000000c ffff8801c6c47bd8c ffffffff82401cd9c ffffffff8112f76bc ffffffff830d45a0c ffffffff84b7cff8c ffffffff84b7cf40c 00000200c740f800c ffff880100010000c 00007f3100000000c 0000000000000130c Call Trace: [<0000000071a7909b>] rcu_read_unlock include/linux/rcupdate.h:930 [inline] [<0000000071a7909b>] gc_worker+0x2d9/0x600 net/netfilter/nf_conntrack_core.c:1006 [<000000007675e7e4>] process_one_work+0x88b/0x1600 kernel/workqueue.c:2114 [<000000005e639f46>] worker_thread+0x5df/0x11d0 kernel/workqueue.c:2251 [<00000000c28a361f>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000ed7731a3>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Code: c83 ce8 c54 c44 c2b c00 ceb c80 c48 cc7 cc7 ce0 cbb c1f c83 ce8 c46 c44 c2b c00 ceb ca6 c0f c1f c40 c00 c48 cb8 c00 c00 c00 c00 c00 cfc cff cdf c55 c48 c89 ce5 c41 c54 c53 c<65> c48 c8b c1c c25 c00 c7e c01 c00 c4c c8d ca3 cd8 c03 c00 c00 c4c c89 ce2 c48 cc1 c