INFO: task syz-executor.4:2111 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.4 D25528 2111 1 0x00000004 0000000000000087 ffff8801cf7f17c0 ffff8801d2397380 ffff8801db621000 ffff8801d26f2f80 ffff8801db621018 ffff8801a1c37598 ffffffff8281af8e ffffffff81bcd83c ffff8801a1c375c8 00ffffff8120553e ffff8801db6218f0 Call Trace: [<00000000f6bea66e>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000316b04d9>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<00000000b3bbde0d>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<00000000b3bbde0d>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<0000000035912ead>] fuse_lock_inode+0xad/0xe0 fs/fuse/inode.c:364 [<00000000a5cdf87f>] fuse_lookup+0x89/0x3b0 fs/fuse/dir.c:406 [<000000004928eb82>] lookup_slow+0x24b/0x480 fs/namei.c:1793 [<000000005ec9f22a>] walk_component+0x71e/0xce0 fs/namei.c:1909 [<0000000094a78295>] link_path_walk+0x8b4/0x1210 fs/namei.c:2245 [<00000000bf06cbed>] path_mountpoint+0x67/0x6d0 fs/namei.c:2821 [<00000000309f743a>] filename_mountpoint+0x17f/0x350 fs/namei.c:2842 [<000000008e45d6d3>] user_path_mountpoint_at+0x3a/0x50 fs/namei.c:2872 [<000000008ad760a1>] SYSC_umount fs/namespace.c:1722 [inline] [<000000008ad760a1>] SyS_umount+0x136/0xd30 fs/namespace.c:1706 [<00000000259c72cc>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<0000000035c5379c>] 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: [<000000000a0b2a99>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<000000000a0b2a99>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<000000003239c4b1>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336 1 lock held by rsyslogd/1900: #0: (&f->f_pos_lock){+.+.+.}, at: [<000000003215abad>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2028: #0: (&tty->ldisc_sem){++++++}, at: [<00000000afa78d16>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+...}, at: [<00000000d26a2c56>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.4/2111: #0: (&type->i_mutex_dir_key#7){++++++}, at: [<0000000050b585b8>] inode_lock_shared include/linux/fs.h:781 [inline] #0: (&type->i_mutex_dir_key#7){++++++}, at: [<0000000050b585b8>] lookup_slow+0x160/0x480 fs/namei.c:1770 #1: (&fi->mutex){+.+.+.}, at: [<0000000035912ead>] fuse_lock_inode+0xad/0xe0 fs/fuse/inode.c:364 2 locks held by syz-executor.5/13256: #0: (sb_writers#13){.+.+.+}, at: [<0000000048e6b697>] sb_start_write include/linux/fs.h:1579 [inline] #0: (sb_writers#13){.+.+.+}, at: [<0000000048e6b697>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391 #1: (&type->i_mutex_dir_key#7){++++++}, at: [<00000000ff0d7ed8>] inode_lock include/linux/fs.h:771 [inline] #1: (&type->i_mutex_dir_key#7){++++++}, at: [<00000000ff0d7ed8>] utimes_common.isra.0+0x2bf/0x5f0 fs/utimes.c:93 2 locks held by syz-executor.5/13350: #0: (sb_writers#13){.+.+.+}, at: [<0000000048e6b697>] sb_start_write include/linux/fs.h:1579 [inline] #0: (sb_writers#13){.+.+.+}, at: [<0000000048e6b697>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391 #1: (&type->i_mutex_dir_key#7){++++++}, at: [<00000000ff0d7ed8>] inode_lock include/linux/fs.h:771 [inline] #1: (&type->i_mutex_dir_key#7){++++++}, at: [<00000000ff0d7ed8>] utimes_common.isra.0+0x2bf/0x5f0 fs/utimes.c:93 2 locks held by syz-executor.5/13477: #0: (sb_writers#13){.+.+.+}, at: [<0000000048e6b697>] sb_start_write include/linux/fs.h:1579 [inline] #0: (sb_writers#13){.+.+.+}, at: [<0000000048e6b697>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391 #1: (&type->i_mutex_dir_key#7){++++++}, at: [<00000000ff0d7ed8>] inode_lock include/linux/fs.h:771 [inline] #1: (&type->i_mutex_dir_key#7){++++++}, at: [<00000000ff0d7ed8>] utimes_common.isra.0+0x2bf/0x5f0 fs/utimes.c:93 2 locks held by syz-executor.5/13729: #0: (sb_writers#13){.+.+.+}, at: [<0000000048e6b697>] sb_start_write include/linux/fs.h:1579 [inline] #0: (sb_writers#13){.+.+.+}, at: [<0000000048e6b697>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391 #1: (&type->i_mutex_dir_key#7){++++++}, at: [<00000000ff0d7ed8>] inode_lock include/linux/fs.h:771 [inline] #1: (&type->i_mutex_dir_key#7){++++++}, at: [<00000000ff0d7ed8>] utimes_common.isra.0+0x2bf/0x5f0 fs/utimes.c:93 2 locks held by syz-executor.5/14389: #0: (sb_writers#13){.+.+.+}, at: [<0000000048e6b697>] sb_start_write include/linux/fs.h:1579 [inline] #0: (sb_writers#13){.+.+.+}, at: [<0000000048e6b697>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391 #1: (&type->i_mutex_dir_key#7){++++++}, at: [<00000000ff0d7ed8>] inode_lock include/linux/fs.h:771 [inline] #1: (&type->i_mutex_dir_key#7){++++++}, at: [<00000000ff0d7ed8>] utimes_common.isra.0+0x2bf/0x5f0 fs/utimes.c:93 2 locks held by syz-executor.4/14613: #0: (&type->i_mutex_dir_key#7){++++++}, at: [<0000000050b585b8>] inode_lock_shared include/linux/fs.h:781 [inline] #0: (&type->i_mutex_dir_key#7){++++++}, at: [<0000000050b585b8>] lookup_slow+0x160/0x480 fs/namei.c:1770 #1: (&fi->mutex){+.+.+.}, at: [<0000000035912ead>] fuse_lock_inode+0xad/0xe0 fs/fuse/inode.c:364 ============================================= 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: [<000000002a781f9b>] __dump_stack lib/dump_stack.c:15 [inline] [<000000002a781f9b>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<000000003dac5cd9>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000db2b7baa>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000f6a36dee>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<0000000061773e02>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<0000000061773e02>] check_hung_task kernel/hung_task.c:126 [inline] [<0000000061773e02>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<0000000061773e02>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000008a503e69>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000fcceda41>] 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 skipped: idling at pc 0xffffffff8282a0e1