9pnet: bogus RWRITE count (33554433 > 20) INFO: task syz-executor3:25170 blocked for more than 140 seconds. Not tainted 4.19.0-rc4+ #26 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor3 D24504 25170 26714 0x00000004 Call Trace: context_switch kernel/sched/core.c:2825 [inline] __schedule+0x86c/0x1ed0 kernel/sched/core.c:3473 schedule+0xfe/0x460 kernel/sched/core.c:3517 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3575 __mutex_lock_common kernel/locking/mutex.c:1002 [inline] __mutex_lock+0xbe7/0x1700 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 __fdget_pos+0x1bb/0x200 fs/file.c:766 fdget_pos include/linux/file.h:70 [inline] ksys_write+0x7f/0x260 fs/read_write.c:593 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457679 Code: Bad RIP value. RSP: 002b:00007f384b4dfc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f384b4e06d4 RCX: 0000000000457679 RDX: 0000000000000014 RSI: 0000000020000340 RDI: 0000000000000005 RBP: 000000000072c0e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004d8550 R14: 00000000004c5146 R15: 0000000000000003 Showing all locks held in the system: 3 locks held by kworker/u4:1/23: #0: 00000000972de65f ((wq_completion)"writeback"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 00000000972de65f ((wq_completion)"writeback"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000972de65f ((wq_completion)"writeback"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000972de65f ((wq_completion)"writeback"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline] #0: 00000000972de65f ((wq_completion)"writeback"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 00000000972de65f ((wq_completion)"writeback"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 00000000972de65f ((wq_completion)"writeback"){+.+.}, at: process_one_work+0xb43/0x1b90 kernel/workqueue.c:2124 #1: 00000000e22327a5 ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: process_one_work+0xb9a/0x1b90 kernel/workqueue.c:2128 #2: 00000000c8b26333 (&type->s_umount_key#65){++++}, at: trylock_super+0x22/0x110 fs/super.c:412 1 lock held by khungtaskd/984: #0: 0000000070b9f184 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x424 kernel/locking/lockdep.c:4435 1 lock held by udevd/3196: 1 lock held by rsyslogd/5226: #0: 0000000019141f0d (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 2 locks held by getty/5316: #0: 00000000762c2a33 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000cd71ed38 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5317: #0: 00000000411f147d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000447de18b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5318: #0: 000000009889bbba (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000031c714d9 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5319: #0: 00000000d2e8f652 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000d9213e62 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5320: #0: 00000000698d1b0f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000000ce9ad96 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5321: #0: 000000002e3f0e5e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000024651092 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5322: #0: 000000009bccd443 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000001449d32d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 3 locks held by syz-executor3/25131: #0: 0000000087ce3ac3 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 #1: 000000005cca8b86 (sb_writers#17){.+.+}, at: file_start_write include/linux/fs.h:2759 [inline] #1: 000000005cca8b86 (sb_writers#17){.+.+}, at: vfs_write+0x42a/0x560 fs/read_write.c:548 #2: 000000006885183b (&sb->s_type->i_mutex_key#20){++++}, at: inode_lock include/linux/fs.h:738 [inline] #2: 000000006885183b (&sb->s_type->i_mutex_key#20){++++}, at: generic_file_write_iter+0xed/0x870 mm/filemap.c:3289 2 locks held by syz-executor3/25169: #0: 000000005cca8b86 (sb_writers#17){.+.+}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 000000005cca8b86 (sb_writers#17){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 #1: 00000000257e8349 (&sb->s_type->i_mutex_key#20){++++}, at: inode_lock include/linux/fs.h:738 [inline] #1: 00000000257e8349 (&sb->s_type->i_mutex_key#20){++++}, at: do_last fs/namei.c:3321 [inline] #1: 00000000257e8349 (&sb->s_type->i_mutex_key#20){++++}, at: path_openat+0x15c7/0x5160 fs/namei.c:3534 1 lock held by syz-executor3/25170: #0: 0000000087ce3ac3 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 984 Comm: khungtaskd Not tainted 4.19.0-rc4+ #26 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.3+0x63/0xa2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1b3/0x1ed lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:144 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:204 [inline] watchdog+0xb3e/0x1050 kernel/hung_task.c:265 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413 Sending NMI from CPU 0 to CPUs 1: INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.101 msecs NMI backtrace for cpu 1 CPU: 1 PID: 3196 Comm: udevd Not tainted 4.19.0-rc4+ #26 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:arch_local_save_flags arch/x86/include/asm/paravirt.h:783 [inline] RIP: 0010:__lock_acquire+0xb0c/0x4ec0 kernel/locking/lockdep.c:3287 Code: 89 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 98 30 00 00 48 83 3d 4a 88 f1 07 00 0f 84 cd 0a 00 00 <9c> 58 0f 1f 44 00 00 f6 c4 02 0f 84 77 f6 ff ff e8 cf 53 2b 02 85 RSP: 0018:ffff8801c75274c0 EFLAGS: 00000086 RAX: dffffc0000000000 RBX: 1ffff10038ea4f15 RCX: 0000000000000000 RDX: 1ffffffff12a453c RSI: 0000000000000000 RDI: ffffffff895229e0 RBP: ffff8801c7527850 R08: 0000000000000001 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000001 R13: ffff8801c719ed18 R14: ffff8801c751e1c0 R15: 0000000000000000 FS: 00007f467a4087a0(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000001c7b32000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline] _raw_spin_lock_irq+0x61/0x80 kernel/locking/spinlock.c:160 spin_lock_irq include/linux/spinlock.h:354 [inline] ep_poll+0x332/0x13d0 fs/eventpoll.c:1776 do_epoll_wait+0x1b0/0x200 fs/eventpoll.c:2198 __do_sys_epoll_wait fs/eventpoll.c:2208 [inline] __se_sys_epoll_wait fs/eventpoll.c:2205 [inline] __x64_sys_epoll_wait+0x97/0xf0 fs/eventpoll.c:2205 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f4679b1c943 Code: 00 31 d2 48 29 c2 64 89 11 48 83 c8 ff eb ea 90 90 90 90 90 90 90 90 83 3d b5 dc 2a 00 00 75 13 49 89 ca b8 e8 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8 3b c4 00 00 48 89 04 24 RSP: 002b:00007ffdd5073eb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e8 RAX: ffffffffffffffda RBX: 0000000000000bb8 RCX: 00007f4679b1c943 RDX: 0000000000000008 RSI: 00007ffdd5073fb0 RDI: 000000000000000a RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000bb8 R11: 0000000000000246 R12: 0000000000000003 R13: 0000000000000000 R14: 0000000001fad1f0 R15: 0000000001fad250