INFO: task syz-executor.2:2170 blocked for more than 140 seconds. Not tainted 4.9.167+ #38 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D25528 2170 1 0x00000004 ffff8801d06cdf00 ffff8801d3b22100 ffff8801db721000 ffff8801d3b6af80 ffff8801db721018 ffff8801a9647988 ffffffff827ffcae 0000000000000000 ffffffff830c1cc0 00ff8801a96479b0 ffff8801db7218f0 1ffff100352c8f20 Call Trace: [<00000000ee914fe6>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000010f82d5>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<00000000857fad25>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<00000000857fad25>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<000000009fc7df63>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 [<000000007bbd7513>] loop_reread_partitions+0x7c/0x90 drivers/block/loop.c:638 [<0000000009288148>] loop_clr_fd+0x7dd/0xa60 drivers/block/loop.c:1082 [<000000000f9ce431>] lo_ioctl+0x7b6/0x1a10 drivers/block/loop.c:1415 [<000000008b712293>] __blkdev_driver_ioctl block/ioctl.c:294 [inline] [<000000008b712293>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590 [<0000000080fecce3>] block_ioctl+0xde/0x120 fs/block_dev.c:1696 [<00000000637b36bb>] vfs_ioctl fs/ioctl.c:43 [inline] [<00000000637b36bb>] file_ioctl fs/ioctl.c:493 [inline] [<00000000637b36bb>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677 [<00000000f6f8b349>] SYSC_ioctl fs/ioctl.c:694 [inline] [<00000000f6f8b349>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [<0000000067e64c0e>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 [<000000003fc37d60>] 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: [<000000009c3bbb2d>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline] #0: (rcu_read_lock){......}, at: [<000000009c3bbb2d>] watchdog+0x13c/0xae0 kernel/hung_task.c:239 #1: (tasklist_lock){.+.+..}, at: [<00000000441e2ba3>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 1 lock held by rsyslogd/1945: #0: (&f->f_pos_lock){+.+.+.}, at: [<00000000e6869a6f>] __fdget_pos+0xa8/0xd0 fs/file.c:781 2 locks held by getty/2073: #0: (&tty->ldisc_sem){++++++}, at: [<0000000002e7d21d>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<00000000fc2fa994>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.2/2170: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<000000003f4bc559>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 #1: (&bdev->bd_mutex){+.+.+.}, at: [<000000009fc7df63>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by syz-executor.5/14135: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000009c0fc6da>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000053cc715d>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 3 locks held by syz-executor.4/2593: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003e4b2b0e>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<00000000661f93b6>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 #2: (loop_ctl_mutex#2){+.+.+.}, at: [<000000009e9a9e0f>] __lo_release drivers/block/loop.c:1642 [inline] #2: (loop_ctl_mutex#2){+.+.+.}, at: [<000000009e9a9e0f>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 1 lock held by blkid/17889: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<000000003f4bc559>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 2 locks held by blkid/17895: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000009c0fc6da>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000053cc715d>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by blkid/17898: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000009c0fc6da>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.167+ #38 ffff8801d98d7cc8 ffffffff81b4f011 0000000000000001 0000000000000000 0000000000000001 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00 ffffffff81b5a2cc 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<0000000027e07194>] __dump_stack lib/dump_stack.c:15 [inline] [<0000000027e07194>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<00000000510e4388>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<000000009c61eb35>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000f710cc15>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<000000006b788d35>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<000000006b788d35>] check_hung_task kernel/hung_task.c:125 [inline] [<000000006b788d35>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [<000000006b788d35>] watchdog+0x661/0xae0 kernel/hung_task.c:239 [<000000008d0b713a>] kthread+0x278/0x310 kernel/kthread.c:211 [<0000000025c262e6>] 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: 30841 Comm: udevd Not tainted 4.9.167+ #38 task: 00000000ccaa1f10 task.stack: 00000000bdc87d19 RIP: 0010:[] c [<00000000e6b88565>] arch_local_irq_disable arch/x86/include/asm/paravirt.h:773 [inline] RIP: 0010:[] c [<00000000e6b88565>] arch_local_irq_save arch/x86/include/asm/paravirt.h:786 [inline] RIP: 0010:[] c [<00000000e6b88565>] lock_acquire+0x77/0x3d0 kernel/locking/lockdep.c:3754 RSP: 0018:ffff8801c84d7788 EFLAGS: 00000046 RAX: 0000000000000046 RBX: 0000000000000046 RCX: 0000000000000002 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8801c908a06c RBP: ffff8801c84d77f0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: ffffffff830d45a0 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000002 FS: 00007f89b1fc67a0(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000001913000 CR3: 00000001a368c000 CR4: 00000000001606b0 DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Stack: 0000000000000046c ffff880100000001c 0000000000000000c ffffffff8423bfa0c 0000000000000001c 0000000000000202c 00000000000000bec 0000000000000000c 0000000000000004c ffffffff8423bfa0c 0000000000000202c 00000000000000bec Call Trace: [<0000000011bcad10>] rcu_lock_acquire include/linux/rcupdate.h:493 [inline] [<0000000011bcad10>] rcu_read_lock include/linux/rcupdate.h:875 [inline] [<0000000011bcad10>] avc_reclaim_node security/selinux/avc.c:529 [inline] [<0000000011bcad10>] avc_alloc_node security/selinux/avc.c:559 [inline] [<0000000011bcad10>] avc_alloc_node+0x1a2/0x3c0 security/selinux/avc.c:547 [<000000003cb9e518>] avc_insert security/selinux/avc.c:670 [inline] [<000000003cb9e518>] avc_compute_av+0x182/0x610 security/selinux/avc.c:976 [<000000005fcbfd3c>] avc_has_perm_noaudit security/selinux/avc.c:1112 [inline] [<000000005fcbfd3c>] avc_has_perm+0x355/0x3a0 security/selinux/avc.c:1146 [<000000003fdbcf10>] selinux_socket_unix_may_send+0x1df/0x2a0 security/selinux/hooks.c:4589 [<000000000c75477e>] security_unix_may_send+0x7b/0xb0 security/security.c:1252 [<000000008106360a>] unix_dgram_sendmsg+0x99b/0xff0 net/unix/af_unix.c:1784 [<00000000721cd891>] sock_sendmsg_nosec net/socket.c:649 [inline] [<00000000721cd891>] sock_sendmsg+0xbe/0x110 net/socket.c:659 [<000000009404ef07>] SYSC_sendto net/socket.c:1684 [inline] [<000000009404ef07>] SyS_sendto+0x201/0x340 net/socket.c:1652 [<0000000067e64c0e>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 [<000000003fc37d60>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Code: c83 ce0 c07 c83 cc0 c03 c38 cd0 c7c c08 c84 cd2 c0f c85 cb7 c02 c00 c00 c8b c83 cac c08 c00 c00 c85 cc0 c0f c85 c0f c01 c00 c00 c9c c58 c0f c1f c44 c00 c00 c48 c89 cc3 cfa c<66> c0f c1f c44 c00 c00 c65 c48 c8b c14 c25 c00 c7e c01 c00 c48 c8d cba cac c08 c00 c