INFO: task kcompactd0:1150 blocked for more than 143 seconds. Not tainted 5.8.0-rc4-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kcompactd0 D29352 1150 2 0x00004000 Call Trace: context_switch kernel/sched/core.c:3453 [inline] __schedule+0x8e1/0x1eb0 kernel/sched/core.c:4178 schedule+0xd0/0x2a0 kernel/sched/core.c:4253 io_schedule+0xb5/0x120 kernel/sched/core.c:5897 wait_on_page_bit_common+0x34f/0xda0 mm/filemap.c:1150 lock_page include/linux/pagemap.h:521 [inline] __unmap_and_move mm/migrate.c:1046 [inline] unmap_and_move mm/migrate.c:1196 [inline] migrate_pages+0x1a2d/0x2e50 mm/migrate.c:1444 compact_zone+0x1cce/0x3a80 mm/compaction.c:2207 kcompactd_do_work+0x2bd/0x770 mm/compaction.c:2575 kcompactd+0x226/0x850 mm/compaction.c:2668 kthread+0x3b5/0x4a0 kernel/kthread.c:291 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 Showing all locks held in the system: 1 lock held by systemd/1: 1 lock held by khungtaskd/1146: #0: ffffffff89bc11c0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5779 1 lock held by khugepaged/1153: 1 lock held by kswapd0/1666: 1 lock held by kswapd1/1667: 4 locks held by kworker/u4:4/2528: 2 locks held by systemd-journal/3868: 2 locks held by systemd-udevd/3876: 1 lock held by systemd-timesyn/4450: 2 locks held by in:imklog/6489: 2 locks held by cron/6479: 2 locks held by agetty/6726: #0: ffff88809de08098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc90000ff02e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x223/0x1a30 drivers/tty/n_tty.c:2156 1 lock held by syz-fuzzer/6795: 2 locks held by syz-fuzzer/6796: 2 locks held by syz-fuzzer/6808: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1146 Comm: khungtaskd Not tainted 5.8.0-rc4-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:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline] watchdog+0xd7d/0x1000 kernel/hung_task.c:295 kthread+0x3b5/0x4a0 kernel/kthread.c:291 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.8.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events nsim_dev_trap_report_work RIP: 0010:mark_held_locks+0x9f/0xe0 kernel/locking/lockdep.c:3609 Code: 42 0f b6 04 28 38 d0 7f 04 84 c0 75 4a 0f b6 46 22 89 c2 83 e2 03 80 fa 01 89 ea 83 da ff a8 04 74 0c 4c 89 e7 e8 51 e8 ff ff <85> c0 74 12 83 c3 01 41 39 9c 24 c8 08 00 00 7f a9 b8 01 00 00 00 RSP: 0000:ffffc90000cbfab8 EFLAGS: 00000082 RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000006 RDX: 1ffffffff18bb3b4 RSI: 0000000000000008 RDI: ffffffff8c5d9da0 RBP: 0000000000000006 R08: 0000000000000000 R09: ffffffff8c58faef R10: fffffbfff18b1f5d R11: 0000000000000000 R12: ffff8880a95a2140 R13: dffffc0000000000 R14: ffff8880a95a2a10 R15: 0000000000000022 FS: 0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000043c7a0 CR3: 000000008e629000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __trace_hardirqs_on_caller kernel/locking/lockdep.c:3635 [inline] lockdep_hardirqs_on_prepare+0x3a2/0x590 kernel/locking/lockdep.c:3686 trace_hardirqs_on+0x5f/0x220 kernel/trace/trace_preemptirq.c:49 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] _raw_spin_unlock_irqrestore+0x62/0xe0 kernel/locking/spinlock.c:191 extract_crng drivers/char/random.c:1026 [inline] _get_random_bytes+0x229/0x6d0 drivers/char/random.c:1562 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:527 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:557 [inline] nsim_dev_trap_report_work+0x759/0xbe0 drivers/net/netdevsim/dev.c:598 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:291 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293