snd_dummy snd_dummy.0: control 0:0:0:syz1:0 is already present INFO: task login:7278 blocked for more than 140 seconds. Not tainted 4.14.169-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. login D25920 7278 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384 schedule+0x92/0x1c0 kernel/sched/core.c:3428 schedule_timeout+0x93b/0xe10 kernel/time/timer.c:1723 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common kernel/sched/completion.c:123 [inline] wait_for_completion+0x27c/0x420 kernel/sched/completion.c:144 flush_work+0x3eb/0x730 kernel/workqueue.c:2891 tty_buffer_flush_work+0x16/0x20 drivers/tty/tty_buffer.c:612 n_tty_read+0x813/0x17d0 drivers/tty/n_tty.c:2199 tty_read+0x171/0x270 drivers/tty/tty_io.c:866 __vfs_read+0x105/0x6a0 fs/read_write.c:411 vfs_read+0x137/0x350 fs/read_write.c:447 SYSC_read fs/read_write.c:574 [inline] SyS_read+0xfd/0x230 fs/read_write.c:567 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x7f3e696aa310 RSP: 002b:00007ffd7d7ecee8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f3e696aa310 RDX: 00000000000001ff RSI: 00007ffd7d7ed150 RDI: 0000000000000000 RBP: 0000000000000000 R08: 00007f3e69f8d700 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd7d7ed150 R13: 0000000000000000 R14: 0000000000000001 R15: 000000000060b798 INFO: task kworker/u4:5:7432 blocked for more than 140 seconds. Not tainted 4.14.169-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:5 D26080 7432 2 0x80000000 Workqueue: events_unbound flush_to_ldisc Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384 schedule+0x92/0x1c0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 flush_to_ldisc+0x39/0x400 drivers/tty/tty_buffer.c:499 process_one_work+0x863/0x1600 kernel/workqueue.c:2114 process_scheduled_works kernel/workqueue.c:2174 [inline] worker_thread+0x787/0x1050 kernel/workqueue.c:2253 kthread+0x319/0x430 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/1057: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4544 2 locks held by login/7278: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7279: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7280: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7281: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7282: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7283: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7284: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 3 locks held by kworker/u4:5/7432: #0: ("events_unbound"){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("events_unbound"){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("events_unbound"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("events_unbound"){+.+.}, at: [] process_one_work+0x76e/0x1600 kernel/workqueue.c:2085 #1: ((&buf->work)){+.+.}, at: [] process_one_work+0x7ab/0x1600 kernel/workqueue.c:2089 #2: (&buf->lock){+.+.}, at: [] flush_to_ldisc+0x39/0x400 drivers/tty/tty_buffer.c:499 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1057 Comm: khungtaskd Not tainted 4.14.169-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+0x142/0x197 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x141/0x189 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:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x5e7/0xb90 kernel/hung_task.c:274 kthread+0x319/0x430 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 7154 Comm: rs:main Q:Reg Not tainted 4.14.169-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8880a8514400 task.stack: ffff8880a9130000 RIP: 0010:generic_make_request_checks+0x77/0x1ac0 block/blk-core.c:2044 RSP: 0018:ffff8880a91377d0 EFLAGS: 00000a06 RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 1ffffffff1067a98 RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8880675e7980 RBP: ffff8880a91378a0 R08: ffff8880a8514ce0 R09: 0000000000000000 R10: ffff8880a9137988 R11: ffff8880675e7a07 R12: ffff8880675e7980 R13: ffff8880675e7980 R14: ffff8880a9137a58 R15: 0000000000000000 FS: 00007f526898c700(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5260005028 CR3: 00000000a920c000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: generic_make_request+0x7d/0xa40 block/blk-core.c:2183 submit_bio+0x1a5/0x3e0 block/blk-core.c:2301 submit_bio_wait+0x108/0x160 block/bio.c:1012 blkdev_issue_flush+0x22a/0x330 block/blk-flush.c:531 ext4_sync_file+0xa78/0x12d0 fs/ext4/fsync.c:157 vfs_fsync_range+0x10e/0x260 fs/sync.c:196 generic_write_sync include/linux/fs.h:2677 [inline] ext4_file_write_iter+0x68a/0xe90 fs/ext4/file.c:279 call_write_iter include/linux/fs.h:1777 [inline] new_sync_write fs/read_write.c:469 [inline] __vfs_write+0x4a7/0x6b0 fs/read_write.c:482 vfs_write+0x198/0x500 fs/read_write.c:544 SYSC_write fs/read_write.c:590 [inline] SyS_write+0xfd/0x230 fs/read_write.c:582 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x7f526a3ea19d RSP: 002b:00007f526898b000 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 000000000000000f RCX: 00007f526a3ea19d RDX: 000000000000000f RSI: 00000000008f0a90 RDI: 0000000000000005 RBP: 00000000008f0a90 R08: 0000000000000000 R09: 00007f5269d68de0 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 00007f526898b480 R14: 000000000000001d R15: 00000000008f0890 Code: 88 c0 ba fb 82 c7 00 f1 f1 f1 f1 c7 40 08 f3 f3 f3 f3 e8 7d 59 61 fe 49 8d 44 24 30 48 89 85 68 ff ff ff 48 c1 e8 03 0f b6 04 18 <84> c0 74 08 3c 03 0f 8e 4c 0f 00 00 45 8b 7c 24 30 31 d2 be 00