INFO: task syz-executor.3:29984 blocked for more than 140 seconds. Not tainted 4.9.194+ #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D25528 29984 1 0x00000004 0000000000000087 ffff88019d645f00 0000000000000000 ffff8801db621000 ffff8801da73af80 ffff8801db621018 ffff8801a130f6a8 ffffffff8281af8e 0000000000000246 ffffffff831f3ca8 00ff88019d6467a8 ffff8801db6218f0 Call Trace: [<000000000daadd32>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<0000000045fb97f0>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<000000001b12dfa4>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<000000001b12dfa4>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<000000004ac14c2d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 [<0000000098c51cc6>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1424 [<000000003c784cd0>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1579 [<000000008ed453ba>] do_dentry_open+0x422/0xd20 fs/open.c:791 [<00000000d2b0a35a>] vfs_open+0x105/0x230 fs/open.c:904 [<00000000884c4848>] do_last fs/namei.c:3541 [inline] [<00000000884c4848>] path_openat+0xbf5/0x2f60 fs/namei.c:3665 [<000000001d094de9>] do_filp_open+0x1a1/0x280 fs/namei.c:3699 [<0000000001a87a63>] do_sys_open+0x2f0/0x610 fs/open.c:1097 [<0000000023c7e23f>] SYSC_open fs/open.c:1115 [inline] [<0000000023c7e23f>] SyS_open+0x2d/0x40 fs/open.c:1110 [<00000000722606b7>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<00000000a60d0aed>] 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: [<00000000f2cd2a60>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<00000000f2cd2a60>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<000000003c51eab8>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336 2 locks held by getty/2021: #0: (&tty->ldisc_sem){++++++}, at: [<0000000061fe6420>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+...}, at: [<000000001f1cb5f5>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.3/29984: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000004ac14c2d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.4/30877: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000004ac14c2d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000068f6e077>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by syz-executor.5/32086: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000004ac14c2d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000068f6e077>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by syz-executor.1/32719: #0: (loop_index_mutex){+.+.+.}, at: [<000000003259d4a7>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<00000000628adbc0>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1987 1 lock held by syz-executor.1/32767: #0: (loop_index_mutex){+.+.+.}, at: [<000000003259d4a7>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 2 locks held by syz-executor.0/32743: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<0000000060c2b460>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<00000000b7918262>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by blkid/32747: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000004ac14c2d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000068f6e077>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by blkid/32748: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000004ac14c2d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000068f6e077>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.194+ #0 ffff8801d98d7cc8 ffffffff81b67001 0000000000000001 0000000000000000 0000000000000001 ffffffff81099d01 dffffc0000000000 ffff8801d98d7d00 ffffffff81b7229c 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<0000000041879565>] __dump_stack lib/dump_stack.c:15 [inline] [<0000000041879565>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<000000005e0a4297>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<000000009635294f>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<000000003b0a04aa>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<000000003e24a3ee>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<000000003e24a3ee>] check_hung_task kernel/hung_task.c:126 [inline] [<000000003e24a3ee>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<000000003e24a3ee>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<00000000cd9f6244>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000eddb3d33>] 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: 2053 Comm: syz-fuzzer Not tainted 4.9.194+ #0 task: 00000000b8da0be8 task.stack: 000000006f1be80e RIP: 0010:[] c [<00000000c74f7a12>] lookup_chain_cache kernel/locking/lockdep.c:2139 [inline] RIP: 0010:[] c [<00000000c74f7a12>] validate_chain kernel/locking/lockdep.c:2236 [inline] RIP: 0010:[] c [<00000000c74f7a12>] __lock_acquire+0xdc0/0x4390 kernel/locking/lockdep.c:3345 RSP: 0018:ffff8801c5dafa20 EFLAGS: 00000046 RAX: 1ffffffff06cf88f RBX: ffffffff8367c460 RCX: 1ffff1003a267a07 RDX: 1ffffffff0785c58 RSI: ffff8801d133d018 RDI: ffffffff8367c478 RBP: ffff8801c5dafbb0 R08: 0000000000000001 R09: 00000000000002c8 R10: ffff8801d133d018 R11: 0000000000000000 R12: dffffc0000000000 R13: ffff8801d133d018 R14: 41862850ce803530 R15: ffff8801d133c740 FS: 000000c4200298e8(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ff570f75000 CR3: 00000001d645d000 CR4: 00000000001606b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Stack: 0000000000000000c ffff8801d133cfe8c ffff8801d133c740c ffffffff8282ac98c ffffffff83031180c ffff8801d1058b00c ffff8801d133c740c ffff8801c5dafa78c ffffffff8120ced5c 0000000000000000c ffff8801db621000c ffffffff83cbdad0c Call Trace: [<00000000d8060672>] lock_acquire+0x133/0x3d0 kernel/locking/lockdep.c:3756 [<00000000829e2ecd>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:112 [inline] [<00000000829e2ecd>] _raw_spin_lock_irqsave+0x50/0x70 kernel/locking/spinlock.c:159 [<0000000090808699>] ep_scan_ready_list+0xb2/0x900 fs/eventpoll.c:629 [<00000000052b2164>] ep_send_events fs/eventpoll.c:1594 [inline] [<00000000052b2164>] ep_poll+0x232/0xa60 fs/eventpoll.c:1699 [<00000000f8c745b1>] SYSC_epoll_wait fs/eventpoll.c:2052 [inline] [<00000000f8c745b1>] SyS_epoll_wait+0x162/0x1e0 fs/eventpoll.c:2017 [<00000000722606b7>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<00000000a60d0aed>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Code: c48 c83 ceb c08 c74 c57 c49 cbc c00 c00 c00 c00 c00 cfc cff cdf c4d c89 cd5 ceb c06 c48 c83 ceb c08 c74 c3f c48 c8d c7b c18 c48 c89 cf8 c48 cc1 ce8 c03 c42 c80 c3c c20 c00 c<0f> c85 c2a c20 c00 c00 c4c c3b c73 c18 c0f c84 c39 cfa cff cff c48 c8d c7b c08 c48 c