syzbot

INFO: task syz-executor.3:23890 blocked for more than 143 seconds.
      Not tainted 5.7.0-rc5-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3  D27776 23890   7327 0x80004004
Call Trace:
 context_switch kernel/sched/core.c:3367 [inline]
 __schedule+0x805/0xc90 kernel/sched/core.c:4083
 schedule+0x188/0x220 kernel/sched/core.c:4158
 schedule_timeout+0x43/0x250 kernel/time/timer.c:1874
 mark_held_locks kernel/locking/lockdep.c:3628 [inline]
 __trace_hardirqs_on_caller kernel/locking/lockdep.c:3657 [inline]
 lockdep_hardirqs_on+0x4a4/0x8a0 kernel/locking/lockdep.c:3702
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline]
 _raw_spin_unlock_irq+0x1f/0x80 kernel/locking/spinlock.c:199
 __down_common+0x28a/0x520 kernel/locking/semaphore.c:220
 down+0x65/0xa0 kernel/locking/semaphore.c:61
 console_lock+0x24/0x70 kernel/printk/printk.c:2314
 do_con_write+0x76/0xf2d0 drivers/tty/vt/vt.c:2596
 __lock_acquire+0x116c/0x2c30 kernel/locking/lockdep.c:4355
 lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4934
 process_output_block drivers/tty/n_tty.c:550 [inline]
 n_tty_write+0x613/0x1170 drivers/tty/n_tty.c:2333
 __mutex_lock_common+0x582/0x2fc0 kernel/locking/mutex.c:964
 add_wait_queue+0x3e/0x130 kernel/sched/wait.c:23
 process_output_block drivers/tty/n_tty.c:550 [inline]
 n_tty_write+0x613/0x1170 drivers/tty/n_tty.c:2333
 mark_held_locks kernel/locking/lockdep.c:3628 [inline]
 __trace_hardirqs_on_caller kernel/locking/lockdep.c:3657 [inline]
 lockdep_hardirqs_on+0x4a4/0x8a0 kernel/locking/lockdep.c:3702
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
 _raw_spin_unlock_irqrestore+0x6f/0xd0 kernel/locking/spinlock.c:191
 con_write+0x20/0x40 drivers/tty/vt/vt.c:3159
 process_output_block drivers/tty/n_tty.c:595 [inline]
 n_tty_write+0xcbf/0x1170 drivers/tty/n_tty.c:2333
 wait_woken+0x240/0x240 kernel/sched/wait.c:442
 do_tty_write drivers/tty/tty_io.c:962 [inline]
 tty_write+0x593/0x940 drivers/tty/tty_io.c:1046
 n_tty_read+0x1bc0/0x1bc0 drivers/tty/n_tty.c:2186
 redirected_tty_write+0xb0/0xb0 drivers/tty/tty_io.c:1067
 __vfs_write+0xa7/0x710 fs/read_write.c:495
 __kernel_write+0x120/0x350 fs/read_write.c:516
 write_pipe_buf+0xf9/0x150 fs/splice.c:809
 splice_from_pipe_feed fs/splice.c:512 [inline]
 __splice_from_pipe+0x329/0x870 fs/splice.c:636
 default_file_splice_write+0x1b0/0x1b0 fs/splice.c:663
 splice_from_pipe fs/splice.c:671 [inline]
 default_file_splice_write+0x112/0x1b0 fs/splice.c:821
 splice_direct_to_actor+0x482/0xb40 fs/splice.c:992
 do_splice_direct+0x340/0x340 fs/splice.c:1073
 do_splice_direct+0x201/0x340 fs/splice.c:1080
 security_file_permission+0xa0/0xc0 security/security.c:1426
 do_sendfile+0x809/0xfe0 fs/read_write.c:1521
 __do_sys_sendfile64 fs/read_write.c:1582 [inline]
 __se_sys_sendfile64 fs/read_write.c:1568 [inline]
 __x64_sys_sendfile64+0x164/0x1a0 fs/read_write.c:1568
 do_syscall_64+0x19/0x1b0 arch/x86/entry/common.c:288
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Showing all locks held in the system:
1 lock held by khungtaskd/1141:
 #0: ffffffff892e85d0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30 net/mptcp/pm_netlink.c:860
1 lock held by in:imklog/6653:
 #0: ffff8880a9343d70 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x25d/0x2f0 fs/file.c:826
2 locks held by syz-executor.0/23888:
4 locks held by syz-executor.3/23890:
 #0: ffff8880a734a098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:267
 #1: ffff8880a734a130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: tty_write_lock drivers/tty/tty_io.c:888 [inline]
 #1: ffff8880a734a130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: do_tty_write drivers/tty/tty_io.c:911 [inline]
 #1: ffff8880a734a130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: tty_write+0x22c/0x940 drivers/tty/tty_io.c:1046
 #2: ffff8880a734a2e8 (&tty->termios_rwsem){++++}-{3:3}, at: n_tty_write+0x1e0/0x1170 drivers/tty/n_tty.c:2316
 #3: ffffc90001640378 (&ldata->output_lock){+.+.}-{3:3}, at: process_output_block drivers/tty/n_tty.c:550 [inline]
 #3: ffffc90001640378 (&ldata->output_lock){+.+.}-{3:3}, at: n_tty_write+0x613/0x1170 drivers/tty/n_tty.c:2333

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 1141 Comm: khungtaskd Not tainted 5.7.0-rc5-syzkaller #0
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+0x1e9/0x30e lib/dump_stack.c:118
 nmi_cpu_backtrace+0x9f/0x180 lib/nmi_backtrace.c:101
 arch_trigger_cpumask_backtrace+0x10/0x10 arch/x86/kernel/apic/hw_nmi.c:38
 nmi_trigger_cpumask_backtrace+0x16a/0x280 lib/nmi_backtrace.c:62
 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
 watchdog+0xd2a/0xd40 kernel/hung_task.c:289
 kthread+0x353/0x380 kernel/kthread.c:268
 hungtask_pm_notify+0x50/0x50 kernel/hung_task.c:265
 kthread_blkcg+0xd0/0xd0 kernel/kthread.c:1247
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 23888 Comm: syz-executor.0 Not tainted 5.7.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x50 kernel/kcov.c:183
Code: e8 25 00 00 00 0f 0b 0f 1f 00 53 48 89 fb e8 17 00 00 00 48 8b 3d b8 4b f8 07 48 89 de 5b e9 57 77 3d 00 cc cc cc cc cc cc cc <48> 8b 04 24 65 48 8b 0c 25 40 1e 02 00 65 8b 15 a8 a8 8e 7e f7 c2
RSP: 0018:ffffc90015db7950 EFLAGS: 00000282
RAX: ffffffff83d1a560 RBX: 0000000000000000 RCX: 0000000000040000
RDX: ffffc90004c29000 RSI: 000000000003ffff RDI: 0000000000040000
RBP: 000000000000000a R08: ffffffff83d1a51b R09: ffffffff83d19c8f
R10: ffff888087936280 R11: 0000000000000002 R12: 000000003533b73a
R13: ffff8880000a0002 R14: fffffffffffffff4 R15: 000000000000000b
FS:  00007f00e2592700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c0001f2020 CR3: 000000009d474000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 vga16fb_fillrect+0xfe0/0x13e0 drivers/video/fbdev/vga16fb.c:922
 bit_clear_margins+0x37b/0x620 drivers/video/fbdev/core/bitblit.c:232
 fbcon_clear_margins drivers/video/fbdev/core/fbcon.c:1381 [inline]
 fbcon_switch+0x1448/0x1e40 drivers/video/fbdev/core/fbcon.c:2363
 redraw_screen+0x4fc/0x16f0 drivers/tty/vt/vt.c:1015
 fbcon_modechanged+0x8d5/0xd90 drivers/video/fbdev/core/fbcon.c:3000
 fb_set_var+0x822/0xcc0 drivers/video/fbdev/core/fbmem.c:1056
 do_fb_ioctl+0x502/0x6f0 drivers/video/fbdev/core/fbmem.c:1109
 fb_write+0x540/0x540 drivers/video/fbdev/core/fbmem.c:849
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl fs/ioctl.c:771 [inline]
 __do_sys_ioctl fs/ioctl.c:780 [inline]
 __se_sys_ioctl+0xf9/0x160 fs/ioctl.c:778
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45ca29
Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f00e2591c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e4ac0 RCX: 000000000045ca29
RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000004
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000002f2 R14: 00000000004c56c8 R15: 00007f00e25926d4