INFO: task hung in n_tty

Kernel	Title	Repro	Cause bisect	Count	Last	Reported	Patched	Status
linux-4.14	INFO: task hung in n_tty_read			6	1521d	1561d	0/1	auto-closed as invalid on 2020/06/25 03:18
android-44	INFO: task hung in n_tty_read			1	1672d	1672d	0/2	auto-closed as invalid on 2020/01/25 18:14
upstream	INFO: task hung in n_tty_read (2) usb serial input	C	error	1	1116d	1112d	0/26	auto-obsoleted due to no activity on 2023/04/25 23:58
upstream	INFO: task hung in n_tty_read serial			3	1537d	1592d	0/26	auto-closed as invalid on 2020/05/09 10:39
linux-4.19	INFO: task hung in n_tty_read (2)			1	576d	576d	0/1	auto-obsoleted due to no activity on 2023/01/25 23:32
linux-4.19	INFO: task hung in n_tty_read			2	1577d	1588d	0/1	auto-closed as invalid on 2020/04/29 17:03

Buffer I/O error on dev loop1p3, logical block 3717, async page read Buffer I/O error on dev loop1p3, logical block 3718, async page read Buffer I/O error on dev loop1p3, logical block 3719, async page read Buffer I/O error on dev loop1p2, logical block 0, async page read INFO: task login:7930 blocked for more than 140 seconds. Not tainted 4.14.231-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. login D25976 7930 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x88b/0x1de0 kernel/sched/core.c:3384 schedule+0x8d/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x80a/0xe90 kernel/time/timer.c:1724 audit: type=1804 audit(1619410549.812:90): pid=13744 uid=0 auid=4294967295 ses=4294967295 op="invalid_pcr" cause="open_writers" comm="syz-executor.5" name="/root/syzkaller-testdir979551456/syzkaller.FhyVKO/741/bus" dev="sda1" ino=15266 res=1 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common+0x272/0x430 kernel/sched/completion.c:123 flush_work+0x3fe/0x770 kernel/workqueue.c:2893 n_tty_read+0x943/0x1680 drivers/tty/n_tty.c:2199 EXT4-fs (loop5): mounting ext3 file system using the ext4 subsystem EXT4-fs (loop5): Can't read superblock on 2nd try tty_read+0x16b/0x260 drivers/tty/tty_io.c:866 __vfs_read+0xe4/0x620 fs/read_write.c:411 vfs_read+0x139/0x340 fs/read_write.c:447 SYSC_read fs/read_write.c:574 [inline] SyS_read+0xf2/0x210 fs/read_write.c:567 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7fc439198910 RSP: 002b:00007fff0462c068 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007fc439198910 RDX: 00000000000001ff RSI: 00007fff0462c370 RDI: 0000000000000000 RBP: 0000000000000000 R08: 00007fc439cb34c0 R09: 00007fff0462c0f0 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 audit: type=1804 audit(1619410550.162:91): pid=13758 uid=0 auid=4294967295 ses=4294967295 op="invalid_pcr" cause="open_writers" comm="syz-executor.5" name="/root/syzkaller-testdir979551456/syzkaller.FhyVKO/741/bus" dev="sda1" ino=15266 res=1 R13: 0000000000000002 R14: 00007fff0462c660 R15: 000055cc15f0b628 INFO: task kworker/u4:5:9190 blocked for more than 140 seconds. Not tainted 4.14.231-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:5 D26616 9190 2 0x80000000 Workqueue: events_unbound flush_to_ldisc Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x88b/0x1de0 kernel/sched/core.c:3384 schedule+0x8d/0x1b0 kernel/sched/core.c:3428 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0x669/0x1310 kernel/locking/mutex.c:893 flush_to_ldisc+0x35/0x3f0 drivers/tty/tty_buffer.c:499 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Showing all locks held in the system: 1 lock held by khungtaskd/1533: #0: (tasklist_lock){.+.+}, at: [<ffffffff8700a357>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548 2 locks held by agetty/7928: #0: (&tty->ldisc_sem){++++}, at: [<ffffffff83549482>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284 #1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8353e803>] n_tty_read+0x1e3/0x1680 drivers/tty/n_tty.c:2156 2 locks held by login/7930: #0: (&tty->ldisc_sem){++++}, at: [<ffffffff83549482>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284 #1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8353e803>] n_tty_read+0x1e3/0x1680 drivers/tty/n_tty.c:2156 3 locks held by kworker/u4:5/9190: #0: ("events_unbound"){+.+.}, at: [<ffffffff813639b0>] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2087 #1: ((&buf->work)){+.+.}, at: [<ffffffff813639e6>] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2091 #2: (&buf->lock){+.+.}, at: [<ffffffff8354bd15>] flush_to_ldisc+0x35/0x3f0 drivers/tty/tty_buffer.c:499 2 locks held by syz-executor.4/27280: #0: (&tty->ldisc_sem){++++}, at: [<ffffffff83549482>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284 #1: (&buf->lock){+.+.}, at: [<ffffffff8356e7ae>] paste_selection+0x10e/0x420 drivers/tty/vt/selection.c:373 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1533 Comm: khungtaskd Not tainted 4.14.231-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x281 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x13a/0x180 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x5b9/0xb40 kernel/hung_task.c:274 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 13769 Comm: syz-executor.1 Not tainted 4.14.231-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff88804775a2c0 task.stack: ffff888051a60000 RIP: 0033:0x41487f RSP: 002b:00007ffc70470250 EFLAGS: 00000202 RAX: 0000000056ba0c51 RBX: 0000000000000d07 RCX: 00007fa56d94e008 RDX: 0000000056ba0c51 RSI: 0000000008cadba5 RDI: 0000000000000c51 RBP: 0000000056ba0c51 R08: 0000000056ba0c55 R09: 0000001b2df2276c R10: 00007ffc70470420 R11: 0000000000000246 R12: 000000000056bfe8 R13: 0000000000000001 R14: 0000000000560000 R15: ffffffff816824c6 FS: 00000000033f1400(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2df23000 CR3: 00000000a0ed4000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 netlink: 12 bytes leftover after parsing attributes in process `syz-executor.4'.