INFO: task kworker/u4:0:7 blocked for more than 143 seconds. Not tainted 5.5.0-rc2-next-20191217-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:0 D23816 7 2 0x80004000 Workqueue: events_unbound flush_to_ldisc Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x934/0x1f90 kernel/sched/core.c:4081 schedule+0xdc/0x2b0 kernel/sched/core.c:4155 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214 __mutex_lock_common kernel/locking/mutex.c:1036 [inline] __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1106 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1121 flush_to_ldisc+0x3d/0x390 drivers/tty/tty_buffer.c:505 process_one_work+0x9af/0x1740 kernel/workqueue.c:2264 worker_thread+0x98/0xe40 kernel/workqueue.c:2410 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 INFO: task login:9125 blocked for more than 143 seconds. Not tainted 5.5.0-rc2-next-20191217-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. login D23064 9125 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x934/0x1f90 kernel/sched/core.c:4081 schedule+0xdc/0x2b0 kernel/sched/core.c:4155 schedule_timeout+0x72b/0xc60 kernel/time/timer.c:1871 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common kernel/sched/completion.c:115 [inline] wait_for_completion+0x29c/0x440 kernel/sched/completion.c:136 __flush_work+0x4fe/0xa50 kernel/workqueue.c:3041 flush_work+0x18/0x20 kernel/workqueue.c:3062 tty_buffer_flush_work+0x16/0x20 drivers/tty/tty_buffer.c:618 n_tty_read+0xaea/0x1bf0 drivers/tty/n_tty.c:2199 tty_read+0x1a0/0x2a0 drivers/tty/tty_io.c:869 __vfs_read+0x8a/0x110 fs/read_write.c:425 vfs_read+0x1f0/0x440 fs/read_write.c:461 ksys_read+0x14f/0x290 fs/read_write.c:587 __do_sys_read fs/read_write.c:597 [inline] __se_sys_read fs/read_write.c:595 [inline] __x64_sys_read+0x73/0xb0 fs/read_write.c:595 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f22513b5310 Code: Bad RIP value. RSP: 002b:00007ffcb5891848 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f22513b5310 RDX: 00000000000001ff RSI: 00007ffcb5891ab0 RDI: 0000000000000000 RBP: 0000000000000000 R08: 00007f2251c98700 R09: 0000000000000000 R10: 00007ffcb5891800 R11: 0000000000000246 R12: 00007ffcb5891ab0 R13: 0000000000000000 R14: 0000000000000001 R15: 000000000060b798 INFO: task syz-executor.3:18954 can't die for more than 144 seconds. syz-executor.3 R running task 26704 18954 9173 0x00004006 Call Trace: __schedule+0x22a/0x1f90 kernel/sched/core.c:4019 schedule+0xdc/0x2b0 kernel/sched/core.c:4155 paste_selection+0x2f5/0x460 drivers/tty/vt/selection.c:367 tioclinux+0x133/0x480 drivers/tty/vt/vt.c:3044 vt_ioctl+0x1a41/0x26d0 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] file_ioctl fs/ioctl.c:545 [inline] do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732 ksys_ioctl+0xab/0xd0 fs/ioctl.c:749 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a919 Code: Bad RIP value. RSP: 002b:00007fe799cb5c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a919 RDX: 0000000020000000 RSI: 000000000000541c RDI: 0000000000000004 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe799cb66d4 R13: 00000000004c5ca8 R14: 00000000004dbf60 R15: 00000000ffffffff Showing all locks held in the system: 3 locks held by kworker/u4:0/7: #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: __write_once_size include/linux/compiler.h:250 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:869 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: set_work_data kernel/workqueue.c:615 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:642 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: process_one_work+0x88b/0x1740 kernel/workqueue.c:2235 #1: ffffc90000cdfdc0 ((work_completion)(&buf->work)){+.+.}, at: process_one_work+0x8c1/0x1740 kernel/workqueue.c:2239 #2: ffff8880aa5bc0a8 (&buf->lock){+.+.}, at: flush_to_ldisc+0x3d/0x390 drivers/tty/tty_buffer.c:505 1 lock held by khungtaskd/1117: #0: ffffffff899afa40 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334 2 locks held by rs:main Q:Reg/9033: #0: ffff8880a2fb9120 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 #1: ffff888099136428 (sb_writers#3){.+.+}, at: file_start_write include/linux/fs.h:2884 [inline] #1: ffff888099136428 (sb_writers#3){.+.+}, at: vfs_write+0x485/0x5d0 fs/read_write.c:557 1 lock held by rsyslogd/9035: #0: ffff8880a2ea86a0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 2 locks held by login/9125: #0: ffff8880a03c8090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000172b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9126: #0: ffff8880a91e4090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900017bb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9127: #0: ffff8880a06d5090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000177b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9128: #0: ffff8880a856d090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000179b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9129: #0: ffff8880a16f7090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900017ab2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9130: #0: ffff8880a8747090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000173b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9131: #0: ffff888099043090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900011402e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.3/18954: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1117 Comm: khungtaskd Not tainted 5.5.0-rc2-next-20191217-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+0x197/0x210 lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x23b/0x28b 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:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:249 [inline] watchdog+0xdf1/0x14e0 kernel/hung_task.c:333 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 9033 Comm: rs:main Q:Reg Not tainted 5.5.0-rc2-next-20191217-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__sanitizer_cov_trace_pc+0x1a/0x50 kernel/kcov.c:183 Code: c3 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 65 48 8b 04 25 c0 1e 02 00 65 8b 15 14 d1 8c 7e 81 e2 00 01 1f 00 <48> 8b 75 08 75 2b 8b 90 88 13 00 00 83 fa 02 75 20 48 8b 88 90 13 RSP: 0018:ffffc900019f71b8 EFLAGS: 00000046 RAX: ffff8880a6c32440 RBX: 0000000000000200 RCX: ffffffff8195a94a RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000007 RBP: ffffc900019f71b8 R08: ffff8880a6c32440 R09: fffffbfff165a7b9 R10: fffffbfff165a7b8 R11: ffffffff8b2d3dc7 R12: ffffea0002056ec0 R13: 0000000000000293 R14: 0000000000000000 R15: ffff88812fffb000 FS: 00007f98c93f9700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000045a8ef CR3: 00000000a4572000 CR4: 00000000001426e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: mod_lruvec_page_state include/linux/memcontrol.h:732 [inline] inc_lruvec_page_state include/linux/memcontrol.h:1266 [inline] __test_set_page_writeback+0xa69/0x1410 mm/page-writeback.c:2806 set_page_writeback include/linux/page-flags.h:542 [inline] ext4_bio_write_page+0x2ab/0x170a fs/ext4/page-io.c:458 mpage_submit_page+0x153/0x2e0 fs/ext4/inode.c:2075 mpage_process_page_bufs+0x666/0x780 fs/ext4/inode.c:2189 mpage_prepare_extent_to_map+0xa05/0xf90 fs/ext4/inode.c:2596 ext4_writepages+0x954/0x2ff0 fs/ext4/inode.c:2724 do_writepages+0xfa/0x2a0 mm/page-writeback.c:2344 __filemap_fdatawrite_range+0x2bc/0x3b0 mm/filemap.c:421 file_write_and_wait_range+0x175/0x210 mm/filemap.c:782 ext4_sync_file+0x466/0x1590 fs/ext4/fsync.c:153 vfs_fsync_range+0x141/0x230 fs/sync.c:197 generic_write_sync include/linux/fs.h:2855 [inline] ext4_buffered_write_iter+0x30a/0x460 fs/ext4/file.c:259 ext4_file_write_iter+0x20d/0x1770 fs/ext4/file.c:547 call_write_iter include/linux/fs.h:1901 [inline] new_sync_write+0x4d3/0x770 fs/read_write.c:483 __vfs_write+0xe1/0x110 fs/read_write.c:496 vfs_write+0x268/0x5d0 fs/read_write.c:558 ksys_write+0x14f/0x290 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:620 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f98cae5719d Code: d1 20 00 00 75 10 b8 01 00 00 00 0f 05 48 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 be fa ff ff 48 89 04 24 b8 01 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 07 fb ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007f98c93f7f90 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000400 RCX: 00007f98cae5719d RDX: 0000000000000400 RSI: 0000000000dc2340 RDI: 0000000000000006 RBP: 0000000000dc2340 R08: 0000000000e6e530 R09: 00007f98ca7d5800 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 00007f98c93f8410 R14: 0000000000e6e530 R15: 0000000000dc2140