syzbot

INFO: task syz-executor.5:11026 can't die for more than 143 seconds.
syz-executor.5  D28360 11026   6841 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:3778 [inline]
 __schedule+0x8e5/0x21e0 kernel/sched/core.c:4527
 schedule+0xd0/0x2a0 kernel/sched/core.c:4602
 io_uring_cancel_files fs/io_uring.c:7897 [inline]
 io_uring_flush+0x740/0xa90 fs/io_uring.c:7914
 filp_close+0xb4/0x170 fs/open.c:1276
 __close_fd+0x2f/0x50 fs/file.c:671
 __do_sys_close fs/open.c:1295 [inline]
 __se_sys_close fs/open.c:1293 [inline]
 __x64_sys_close+0x69/0x100 fs/open.c:1293
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x416b81
Code: Bad RIP value.
RSP: 002b:00007ffe3f2afcf0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 0000000000000007 RCX: 0000000000416b81
RDX: 0000000000000000 RSI: 0000000001190f98 RDI: 0000000000000006
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 00007ffe3f2afde0 R11: 0000000000000293 R12: 0000000001191058
R13: 0000000000198fd3 R14: ffffffffffffffff R15: 000000000118cfec
INFO: task syz-executor.5:11026 blocked for more than 143 seconds.
      Not tainted 5.8.0-next-20200814-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5  D28360 11026   6841 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:3778 [inline]
 __schedule+0x8e5/0x21e0 kernel/sched/core.c:4527
 schedule+0xd0/0x2a0 kernel/sched/core.c:4602
 io_uring_cancel_files fs/io_uring.c:7897 [inline]
 io_uring_flush+0x740/0xa90 fs/io_uring.c:7914
 filp_close+0xb4/0x170 fs/open.c:1276
 __close_fd+0x2f/0x50 fs/file.c:671
 __do_sys_close fs/open.c:1295 [inline]
 __se_sys_close fs/open.c:1293 [inline]
 __x64_sys_close+0x69/0x100 fs/open.c:1293
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x416b81
Code: Bad RIP value.
RSP: 002b:00007ffe3f2afcf0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 0000000000000007 RCX: 0000000000416b81
RDX: 0000000000000000 RSI: 0000000001190f98 RDI: 0000000000000006
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 00007ffe3f2afde0 R11: 0000000000000293 R12: 0000000001191058
R13: 0000000000198fd3 R14: ffffffffffffffff R15: 000000000118cfec

Showing all locks held in the system:
1 lock held by khungtaskd/1172:
 #0: ffffffff89c66c40 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5825
2 locks held by in:imklog/6520:
 #0: ffff8880932b8b70 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:930
 #1: ffff8880ae635e18 (&rq->lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1292 [inline]
 #1: ffff8880ae635e18 (&rq->lock){-.-.}-{2:2}, at: __schedule+0x232/0x21e0 kernel/sched/core.c:4445
2 locks held by agetty/6757:
 #0: ffff88808b0ef098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267
 #1: ffffc90000fe42e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x223/0x1a30 drivers/tty/n_tty.c:2156

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

NMI backtrace for cpu 1
CPU: 1 PID: 1172 Comm: khungtaskd Not tainted 5.8.0-next-20200814-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+0x18f/0x20d lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:147 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:253 [inline]
 watchdog+0xd89/0xf30 kernel/hung_task.c:339
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3889 Comm: systemd-journal Not tainted 5.8.0-next-20200814-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:0xffffffffa0012c0c
Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc <0f> 1f 44 00 00 55 48 89 e5 48 81 ec 00 00 00 00 53 41 55 41 56 41
RSP: 0018:ffffc90005387d90 EFLAGS: 00000246
RAX: 1ffff920001b9c06 RBX: ffff888097161800 RCX: dffffc0000000000
RDX: ffff8880940320c0 RSI: ffffc90000dce038 RDI: ffffc90005387e40
RBP: ffffc90000dce000 R08: 0000000000000001 R09: 0000000000000001
R10: 000000007fff0000 R11: 0000000000000000 R12: dffffc0000000000
R13: 000000007fff0000 R14: 000000007fff0000 R15: ffffc90005387e40
FS:  00007fd623f568c0(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd620f8a028 CR3: 0000000094958000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace: