INFO: task kworker/u8:1:13 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:1 state:D stack:21536 pid:13 tgid:13 ppid:2 task_flags:0x4208060 flags:0x00080000
Workqueue: writeback wb_workfn (flush-7:8)
Call Trace:
context_switch kernel/sched/core.c:5295 [inline]
__schedule+0x1553/0x5240 kernel/sched/core.c:6908
__schedule_loop kernel/sched/core.c:6990 [inline]
rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7286
rt_mutex_slowlock_block kernel/locking/rtmutex.c:1647 [inline]
__rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
__rt_mutex_slowlock_locked+0x1f8f/0x25c0 kernel/locking/rtmutex.c:1760
rt_mutex_slowlock+0xbd/0x170 kernel/locking/rtmutex.c:1800
__rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
rwbase_write_lock+0x14d/0x730 kernel/locking/rwbase_rt.c:244
f2fs_down_write fs/f2fs/f2fs.h:2407 [inline]
f2fs_down_write_trace fs/f2fs/checkpoint.c:180 [inline]
f2fs_issue_checkpoint+0x437/0x790 fs/f2fs/checkpoint.c:2104
f2fs_balance_fs_bg+0x574/0x9d0 fs/f2fs/segment.c:545
f2fs_write_node_pages+0x158/0x700 fs/f2fs/node.c:2251
do_writepages+0x32e/0x550 mm/page-writeback.c:2554
__writeback_single_inode+0x133/0x11a0 fs/fs-writeback.c:1750
writeback_sb_inodes+0x995/0x19d0 fs/fs-writeback.c:2042
__writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2118
wb_writeback+0x46a/0xb70 fs/fs-writeback.c:2229
wb_check_old_data_flush fs/fs-writeback.c:2333 [inline]
wb_do_writeback fs/fs-writeback.c:2386 [inline]
wb_workfn+0xb52/0xf60 fs/fs-writeback.c:2414
process_one_work kernel/workqueue.c:3275 [inline]
process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358
worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Showing all locks held in the system:
4 locks held by kworker/u8:1/13:
#0: ffff88801aabc138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3250 [inline]
#0: ffff88801aabc138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9ea/0x1830 kernel/workqueue.c:3358
#1: ffffc90000127c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
#1: ffffc90000127c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa25/0x1830 kernel/workqueue.c:3358
#2: ffff88803987c0d0 (&type->s_umount_key#54){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:565
#3: ffff888056fd1a98 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write fs/f2fs/f2fs.h:2407 [inline]
#3: ffff888056fd1a98 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write_trace fs/f2fs/checkpoint.c:180 [inline]
#3: ffff888056fd1a98 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_issue_checkpoint+0x437/0x790 fs/f2fs/checkpoint.c:2104
1 lock held by khungtaskd/39:
#0: ffffffff8ddcb880 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
#0: ffffffff8ddcb880 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
#0: ffffffff8ddcb880 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
6 locks held by kworker/u8:10/3109:
#0: ffff88801aee1138 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3250 [inline]
#0: ffff88801aee1138 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x9ea/0x1830 kernel/workqueue.c:3358
#1: ffffc9000e6b7c40 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
#1: ffffc9000e6b7c40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0xa25/0x1830 kernel/workqueue.c:3358
#2: ffffffff8f14c000 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf4/0x800 net/core/net_namespace.c:675
#3: ffff8880388620d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
#3: ffff8880388620d8 (&dev->mutex){....}-{4:4}, at: devl_dev_lock net/devlink/devl_internal.h:108 [inline]
#3: ffff8880388620d8 (&dev->mutex){....}-{4:4}, at: devlink_pernet_pre_exit+0x117/0x3f0 net/devlink/core.c:504
#4: ffff88805e1a6300 (&devlink->lock_key#18){+.+.}-{4:4}, at: devl_lock net/devlink/core.c:274 [inline]
#4: ffff88805e1a6300 (&devlink->lock_key#18){+.+.}-{4:4}, at: devl_dev_lock net/devlink/devl_internal.h:109 [inline]
#4: ffff88805e1a6300 (&devlink->lock_key#18){+.+.}-{4:4}, at: devlink_pernet_pre_exit+0x129/0x3f0 net/devlink/core.c:504
#5: ffffffff8f15a7b8 (rtnl_mutex){+.+.}-{4:4}, at: nsim_destroy+0xed/0x680 drivers/net/netdevsim/netdev.c:1177
2 locks held by getty/5553:
#0: ffff8880327420a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc90003e8b2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13c0 drivers/tty/n_tty.c:2211
1 lock held by syz-executor/7064:
4 locks held by syz.8.161/7095:
2 locks held by syz.7.237/7858:
#0: ffff88803987c0d0 (&type->s_umount_key#54){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
#0: ffff88803987c0d0 (&type->s_umount_key#54){++++}-{4:4}, at: super_lock+0x2d6/0x3d0 fs/super.c:122
#1: ffff8880265b48c0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:398 [inline]
#1: ffff8880265b48c0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x1c5/0xc10 fs/fs-writeback.c:2922
1 lock held by syz-executor/9439:
#0: ffffffff8f15a7b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
#0: ffffffff8f15a7b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
#0: ffffffff8f15a7b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8a1/0x1be0 net/core/rtnetlink.c:4071
4 locks held by syz.3.434/9483:
1 lock held by udevadm/9530:
2 locks held by rm/9531:
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 39 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/27/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x135/0x170 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
watchdog+0xfd9/0x1030 kernel/hung_task.c:515
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 1185 Comm: irq/33-virtio1- Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/27/2026
RIP: 0010:unwind_next_frame+0x138b/0x23c0 arch/x86/kernel/unwind_orc.c:656
Code: b3 00 48 8b 14 24 4d 89 3c 24 41 0f b6 44 2d 00 84 c0 0f 85 02 0e 00 00 c6 03 00 4c 8b 64 24 48 4c 8b 7c 24 28 48 8b 44 24 40 <0f> b6 04 28 84 c0 0f 85 6c 0b 00 00 41 0f b6 04 2f 84 c0 0f 85 83
RSP: 0000:ffffc90005bbef18 EFLAGS: 00000246
RAX: 1ffffffff1fec9cb RBX: ffffc90005bbf020 RCX: 0000000000000000
RDX: ffffffff8ff64e58 RSI: 0000000000000000 RDI: ffffc90005bbf048
RBP: dffffc0000000000 R08: ffffc90005bbf047 R09: 0000000000000000
R10: ffffc90005bbf038 R11: fffff52000b77e09 R12: ffffc90005bbf038
R13: 1ffff92000b77dff R14: ffffc90005bbefe8 R15: 1ffffffff1fec9cb
FS: 0000000000000000(0000) GS:ffff88812643c000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f55cf251d71 CR3: 0000000034380000 CR4: 00000000003526f0
Call Trace:
arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
unpoison_slab_object mm/kasan/common.c:340 [inline]
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4542 [inline]
kmem_cache_alloc_bulk_noprof+0x4a1/0x790 mm/slub.c:7291
napi_skb_cache_get+0x263/0x410 net/core/skbuff.c:292
__alloc_skb+0x146/0x7d0 net/core/skbuff.c:691
napi_alloc_skb+0x9d/0x780 net/core/skbuff.c:853
page_to_skb+0x2ce/0x870 drivers/net/virtio_net.c:887
receive_mergeable drivers/net/virtio_net.c:2497 [inline]
receive_buf+0x546/0x1900 drivers/net/virtio_net.c:2643
virtnet_receive_packets drivers/net/virtio_net.c:2970 [inline]
virtnet_receive drivers/net/virtio_net.c:2994 [inline]
virtnet_poll+0x219b/0x2f80 drivers/net/virtio_net.c:3083
__napi_poll+0xaf/0x580 net/core/dev.c:7692
napi_poll net/core/dev.c:7755 [inline]
net_rx_action+0x696/0xe00 net/core/dev.c:7912
handle_softirqs+0x1de/0x6f0 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
__local_bh_enable_ip+0x170/0x2b0 kernel/softirq.c:302
local_bh_enable include/linux/bottom_half.h:33 [inline]
irq_forced_thread_fn+0xe9/0x120 kernel/irq/manage.c:1168
irq_thread+0x4c9/0x740 kernel/irq/manage.c:1271
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245