[v6.6] INFO: task hung in _free_event

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c2603c511feb Linux 6.6.93
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15e8c90c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=486bade17c8c30b9
dashboard link: https://syzkaller.appspot.com/bug?extid=a88e5b05a992af96c7be
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5819843271d0/disk-c2603c51.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/113f268f936d/vmlinux-c2603c51.xz
kernel image: https://storage.googleapis.com/syzbot-assets/493dd7e2863f/bzImage-c2603c51.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a88e5b...@syzkaller.appspotmail.com

INFO: task syz.3.2336:11069 blocked for more than 143 seconds.
Not tainted 6.6.93-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.2336 state:D stack:23272 pid:11069 ppid:5769 flags:0x00004006
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x14e2/0x4580 kernel/sched/core.c:6700
schedule+0xbd/0x170 kernel/sched/core.c:6774
perf_pending_task_sync kernel/events/core.c:5215 [inline]
_free_event+0x174/0xf30 kernel/events/core.c:5221
put_event kernel/events/core.c:5349 [inline]
perf_event_release_kernel+0x836/0x8c0 kernel/events/core.c:5474
perf_release+0x3b/0x40 kernel/events/core.c:5484
__fput+0x234/0x970 fs/file_table.c:384
task_work_run+0x1ce/0x250 kernel/task_work.c:239
get_signal+0x1235/0x1400 kernel/signal.c:2678
arch_do_signal_or_restart+0x96/0x780 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fbfbd98e929
RSP: 002b:00007fbfbe82dfe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: fffffffffffffffc RBX: 00007fbfbdbb5fa0 RCX: 00007fbfbd98e929
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000043001000
RBP: 00007fbfbda10b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fbfbdbb5fa0 R15: 00007ffe2d7121a8
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
#0: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
#0: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
#0: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
3 locks held by kworker/u4:5/1001:
#0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#1: ffffc9000403fd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc9000403fd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#2: ffffffff8dfaea88 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:286
3 locks held by kworker/0:3/2193:
#0: ffff888017870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#0: ffff888017870938 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#1: ffffc900050d7d00 (deferred_process_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc900050d7d00 (deferred_process_work){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#2: ffffffff8dfaea88 (rtnl_mutex){+.+.}-{3:3}, at: switchdev_deferred_process_work+0xe/0x20 net/switchdev/switchdev.c:104
2 locks held by kworker/u4:6/2950:
#0: ffff8880b8e3c458 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:558
#1: ffffc9000bac7d00 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc9000bac7d00 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
5 locks held by kworker/u4:9/3435:
#0: ffff888017873938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#0: ffff888017873938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#1: ffffc9000c127d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc9000c127d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#2: ffffffff8dfa1c90 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x136/0xb90 net/core/net_namespace.c:606
#3: ffffffff8dfaea88 (rtnl_mutex){+.+.}-{3:3}, at: default_device_exit_batch+0xe9/0xa60 net/core/dev.c:11594
#4: ffffffff8cd35738 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:292 [inline]
#4: ffffffff8cd35738 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x448/0x830 kernel/rcu/tree_exp.h:1004
2 locks held by dhcpcd/5438:
#0: ffff88801e31b688 (nlk_cb_mutex-ROUTE){+.+.}-{3:3}, at: __netlink_dump_start+0xf4/0x810 net/netlink/af_netlink.c:2328
#1: ffffffff8dfaea88 (rtnl_mutex){+.+.}-{3:3}, at: netlink_dump+0x723/0xe10 net/netlink/af_netlink.c:2255
2 locks held by getty/5534:
#0: ffff88802d35e0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000326b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
3 locks held by kworker/1:8/5839:
#0: ffff88802c781138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#0: ffff88802c781138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#1: ffffc900048afd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc900048afd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#2: ffffffff8dfaea88 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xd0/0x14e0 net/ipv6/addrconf.c:4164
2 locks held by kworker/0:5/5840:
#0: ffff888017872538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#0: ffff888017872538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#1: ffffc9000482fd00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc9000482fd00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
2 locks held by syz-executor/14644:
#0: ffffffff8e013810 (cb_lock){++++}-{3:3}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1074
#1: ffffffff8dfaea88 (rtnl_mutex){+.+.}-{3:3}, at: nl80211_pre_doit+0x5f/0x930 net/wireless/nl80211.c:16515
3 locks held by kworker/0:6/14684:
#0: ffff88802c781138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#0: ffff88802c781138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#1: ffffc90003607d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc90003607d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#2: ffffffff8dfaea88 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xd0/0x14e0 net/ipv6/addrconf.c:4164
7 locks held by syz-executor/14737:
#0: ffff888031f6a418 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x20e/0x940 fs/read_write.c:580
#1: ffff8880266f4088 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1e9/0x4d0 fs/kernfs/file.c:325
#2: ffff888023d453e8 (kn->active#53){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x20c/0x4d0 fs/kernfs/file.c:326
#3: ffffffff8d898b08 (nsim_bus_dev_list_lock){+.+.}-{3:3}, at: del_device_store+0xd2/0x360 drivers/net/netdevsim/bus.c:209
#4: ffff8880675c40e8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:992 [inline]
#4: ffff8880675c40e8 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1095 [inline]
#4: ffff8880675c40e8 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xb6/0x7a0 drivers/base/dd.c:1292
#5: ffff8880675c5250 (&devlink->lock_key#14){+.+.}-{3:3}, at: nsim_drv_remove+0x50/0x160 drivers/net/netdevsim/dev.c:1675
#6: ffffffff8dfaea88 (rtnl_mutex){+.+.}-{3:3}, at: unregister_nexthop_notifier+0x7c/0x1f0 net/ipv4/nexthop.c:3639
1 lock held by syz-executor/14754:
#0: ffffffff8dfaea88 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
#0: ffffffff8dfaea88 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x76f/0xf10 net/core/rtnetlink.c:6472
1 lock held by syz-executor/14785:
#0: ffffffff8dfaea88 (rtnl_mutex){+.+.}-{3:3}, at: __tun_chr_ioctl+0x3b9/0x1fd0 drivers/net/tun.c:3121

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted 6.6.93-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x39b/0x3d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
watchdog+0xf41/0xf80 kernel/hung_task.c:379
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 2950 Comm: kworker/u4:6 Not tainted 6.6.93-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:memset_orig+0x15/0xac arch/x86/lib/memset_64.S:52
Code: f0 48 89 d1 f3 aa 4c 89 c8 c3 90 90 90 90 90 90 90 90 90 90 90 66 0f 1f 00 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01 01 01 <48> 0f af c1 41 89 f9 41 83 e1 07 75 6c 48 89 d1 48 c1 e9 06 74 35
RSP: 0018:ffffc9000bac7230 EFLAGS: 00000202
RAX: 0101010101010101 RBX: ffffc9000bac7340 RCX: 0000000000000000
RDX: 0000000000000010 RSI: 0000000000000000 RDI: ffffc9000bac7358
RBP: ffffc9000bac7358 R08: ffffc9000bac7367 R09: 1ffff92001758e6c
R10: ffffc9000bac7358 R11: fffff52001758e6d R12: ffffc9000bac7308
R13: dffffc0000000000 R14: ffffffff81d26553 R15: ffffffff8ed71b26
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000558d1b480000 CR3: 000000000cb30000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
<TASK>
unwind_next_frame+0x1648/0x2970 arch/x86/kernel/unwind_orc.c:592
arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
save_stack+0xf7/0x1f0 mm/page_owner.c:128
__set_page_owner+0x1d/0x60 mm/page_owner.c:192
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
prep_new_page mm/page_alloc.c:1561 [inline]
get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
__alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
alloc_slab_page+0x5d/0x170 mm/slub.c:1876
allocate_slab mm/slub.c:2023 [inline]
new_slab+0x87/0x2e0 mm/slub.c:2076
___slab_alloc+0xc6d/0x12f0 mm/slub.c:3230
__slab_alloc mm/slub.c:3329 [inline]
__slab_alloc_node mm/slub.c:3382 [inline]
slab_alloc_node mm/slub.c:3475 [inline]
__kmem_cache_alloc_node+0x1a2/0x260 mm/slub.c:3524
__do_kmalloc_node mm/slab_common.c:1006 [inline]
__kmalloc_node_track_caller+0xa2/0x230 mm/slab_common.c:1027
kmalloc_reserve+0x117/0x260 net/core/skbuff.c:581
__alloc_skb+0x138/0x2c0 net/core/skbuff.c:650
alloc_skb include/linux/skbuff.h:1284 [inline]
nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline]
nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline]
nsim_dev_trap_report_work+0x293/0xb00 drivers/net/netdevsim/dev.c:851
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>


---
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If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
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(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 6282921b6825 Linux 6.6.94
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=178f1d0c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427

dashboard link: https://syzkaller.appspot.com/bug?extid=a88e5b05a992af96c7be
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1160f5d4580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1560f5d4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bb8094930023/disk-6282921b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6b695542f7a7/vmlinux-6282921b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f899d5f4fdd2/bzImage-6282921b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a88e5b...@syzkaller.appspotmail.com

INFO: task syz-executor380:5905 blocked for more than 143 seconds.
Not tainted 6.6.94-syzkaller #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

task:syz-executor380 state:D stack:24232 pid:5905 ppid:5792 flags:0x00004002

Call Trace:
<TASK>
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x14e2/0x4580 kernel/sched/core.c:6700
schedule+0xbd/0x170 kernel/sched/core.c:6774
perf_pending_task_sync kernel/events/core.c:5215 [inline]
_free_event+0x174/0xf30 kernel/events/core.c:5221
put_event kernel/events/core.c:5349 [inline]
perf_event_release_kernel+0x836/0x8c0 kernel/events/core.c:5474
perf_release+0x3b/0x40 kernel/events/core.c:5484
__fput+0x234/0x970 fs/file_table.c:384
task_work_run+0x1ce/0x250 kernel/task_work.c:239

exit_task_work include/linux/task_work.h:43 [inline]
do_exit+0x903/0x23c0 kernel/exit.c:874
do_group_exit+0x21b/0x2d0 kernel/exit.c:1023
get_signal+0x12fc/0x1400 kernel/signal.c:2902

arch_do_signal_or_restart+0x96/0x780 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
entry_SYSCALL_64_after_hwframe+0x68/0xd2

RIP: 0033:0x7f4877433ab9
RSP: 002b:00007ffe12566a68 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: fffffffffffffff2 RBX: 0000000000000000 RCX: 00007f4877433ab9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000630c1000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000006
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe12566a7c
R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001

</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
#0: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
#0: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
#0: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633

2 locks held by getty/5538:
#0: ffff888031c520a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243

#1: ffffc9000326b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217

=============================================

NMI backtrace for cpu 1

CPU: 1 PID: 29 Comm: khungtaskd Not tainted 6.6.94-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x39b/0x3d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
watchdog+0xf41/0xf80 kernel/hung_task.c:379
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0

CPU: 0 PID: 5130 Comm: klogd Not tainted 6.6.94-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025

RIP: 0010:find_next_and_bit include/linux/find.h:93 [inline]
RIP: 0010:select_idle_smt kernel/sched/fair.c:7350 [inline]
RIP: 0010:select_idle_sibling kernel/sched/fair.c:7644 [inline]
RIP: 0010:select_task_rq_fair+0x1eb4/0x3220 kernel/sched/fair.c:8235
Code: c0 88 18 02 00 49 01 c6 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 4c 89 f7 e8 1f 87 7e 00 4d 8b 36 <48> 89 e8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74
RSP: 0018:ffffc900032777b8 EFLAGS: 00000046
RAX: 1ffff110171c4311 RBX: ffff88807cdb4018 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff88807cdb4028 R08: dffffc0000000000 R09: 1ffffffff21b0aa4
R10: dffffc0000000000 R11: fffffbfff21b0aa5 R12: 0000000000000000
R13: ffffffff8c7bda30 R14: 0000000000000003 R15: ffffffff8c7bda30
FS: 00007f9c5c395c80(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 000055b5e8e75660 CR3: 000000002fea0000 CR4: 00000000003506f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000

DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
select_task_rq kernel/sched/core.c:3634 [inline]
try_to_wake_up+0x618/0x10b0 kernel/sched/core.c:4334
autoremove_wake_function+0x17/0x100 kernel/sched/wait.c:424
__wake_up_common+0x2a4/0x4e0 kernel/sched/wait.c:107
__wake_up_common_lock kernel/sched/wait.c:138 [inline]
__wake_up_sync_key+0x111/0x190 kernel/sched/wait.c:213
sock_def_readable+0x1e1/0x430 net/core/sock.c:3329
unix_dgram_sendmsg+0x10cc/0x1720 net/unix/af_unix.c:2089
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
__sys_sendto+0x46a/0x620 net/socket.c:2201
__do_sys_sendto net/socket.c:2213 [inline]
__se_sys_sendto net/socket.c:2209 [inline]
__x64_sys_sendto+0xde/0xf0 net/socket.c:2209
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9c5c4e5407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffc63e8fbc0 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f9c5c395c80 RCX: 00007f9c5c4e5407
RDX: 000000000000003d RSI: 00007ffc63e8fd00 RDI: 0000000000000003
RBP: 00007ffc63e90130 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000004000 R11: 0000000000000202 R12: 00007ffc63e90148
R13: 00007ffc63e8fd00 R14: 0000000000000022 R15: 00007ffc63e8fd00
</TASK>


---
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