syzbot


INFO: task hung in __lru_add_drain_all (3)

Status: upstream: reported on 2026/05/01 08:27
Reported-by: syzbot+f86fd46095cba8c1fc12@syzkaller.appspotmail.com
First crash: 29d, last: 8d11h
Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: task hung in __lru_add_drain_all (3) 1 5 14d 80d 0/3 upstream: reported on 2026/03/10 22:55
linux-6.6 INFO: task hung in __lru_add_drain_all 1 1 207d 207d 0/2 auto-obsoleted due to no activity on 2026/02/12 06:31
android-6-12 INFO: task hung in __lru_add_drain_all (2) 1 1 9d06h 9d06h 0/1 premoderation: reported on 2026/05/21 15:31
linux-6.1 INFO: task hung in __lru_add_drain_all (2) 1 1 362d 362d 0/3 auto-obsoleted due to no activity on 2025/09/09 22:30
linux-5.15 INFO: task hung in __lru_add_drain_all 1 1 1133d 1133d 0/3 auto-obsoleted due to no activity on 2023/08/21 02:18
linux-6.1 INFO: task hung in __lru_add_drain_all 1 1 743d 743d 0/3 auto-obsoleted due to no activity on 2024/08/25 20:43
upstream INFO: task hung in __lru_add_drain_all (2) mm 1 syz error 272 405d 742d 0/29 auto-obsoleted due to no activity on 2025/06/29 18:01
upstream INFO: task hung in __lru_add_drain_all net 1 C done error 71 930d 1730d 0/29 auto-obsoleted due to no activity on 2024/02/20 10:46
linux-5.15 INFO: task hung in __lru_add_drain_all (2) 1 1 673d 673d 0/3 auto-obsoleted due to no activity on 2024/11/03 03:56
android-6-12 INFO: task hung in __lru_add_drain_all 1 1 208d 208d 0/1 auto-obsoleted due to no activity on 2026/02/01 19:21

Sample crash report:
INFO: task khugepaged:33 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:khugepaged      state:D stack:28304 pid:   33 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2093
 do_wait_for_common+0x2a2/0x450 kernel/sched/completion.c:85
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x48/0x60 kernel/sched/completion.c:138
 __flush_work+0x15a/0x210 kernel/workqueue.c:3094
 __lru_add_drain_all+0x9ce/0xac0 mm/swap.c:833
 khugepaged_do_scan mm/khugepaged.c:2276 [inline]
 khugepaged+0x13a/0x11f0 mm/khugepaged.c:2337
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
INFO: task kworker/u4:3:155 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:3    state:D stack:23152 pid:  155 ppid:     2 flags:0x00004000
Workqueue: events_unbound fsnotify_connector_destroy_workfn
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2093
 do_wait_for_common+0x2a2/0x450 kernel/sched/completion.c:85
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x48/0x60 kernel/sched/completion.c:138
 __synchronize_srcu+0x2bb/0x350 kernel/rcu/srcutree.c:930
 fsnotify_connector_destroy_workfn+0x40/0xa0 fs/notify/mark.c:234
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
INFO: task syz-executor:4204 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D
 stack:21136 pid: 4204 ppid:     1 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xcfc/0x2400 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 synchronize_rcu_expedited+0x3a5/0x750 kernel/rcu/tree_exp.h:845
 namespace_unlock+0x23f/0x430 fs/namespace.c:1459
 do_umount fs/namespace.c:1683 [inline]
 path_umount+0xf64/0xfd0 fs/namespace.c:1766
 ksys_umount fs/namespace.c:1789 [inline]
 __do_sys_umount fs/namespace.c:1794 [inline]
 __se_sys_umount fs/namespace.c:1792 [inline]
 __x64_sys_umount+0x12d/0x170 fs/namespace.c:1792
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f87107e2097
RSP: 002b:00007ffe713709c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: ffffffffffffffda RBX: 00007f87108761ca RCX: 00007f87107e2097
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffe71370a80
RBP: 00007ffe71370a80 R08: 00007ffe71371a80 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe71371b10
R13: 00007f87108761ca R14: 0000000000050306 R15: 00007ffe71371b50
 </TASK>
INFO: task kworker/u4:6:4271 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:6    state:D
 stack:22096 pid: 4271 ppid:     2 flags:0x00004000
Workqueue: events_unbound fsnotify_mark_destroy_workfn

Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2093
 do_wait_for_common+0x2a2/0x450 kernel/sched/completion.c:85
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x48/0x60 kernel/sched/completion.c:138
 __synchronize_srcu+0x2bb/0x350 kernel/rcu/srcutree.c:930
 fsnotify_mark_destroy_workfn+0x106/0x2f0 fs/notify/mark.c:924
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
INFO: task syz.0.564:6568 blocked for more than 145 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.564       state:D
 stack:27600 pid: 6568 ppid:  4189 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 synchronize_rcu_expedited+0x5c1/0x750 kernel/rcu/tree_exp.h:861
 __tun_detach+0x81f/0x1500 drivers/net/tun.c:670
 tun_detach drivers/net/tun.c:702 [inline]
 tun_chr_close+0x109/0x1b0 drivers/net/tun.c:3440
 __fput+0x234/0x930 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f5e46704e59
RSP: 002b:00007ffc5c5b8d48 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ffc5c5b8e30 RCX: 00007f5e46704e59
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 000000000004fc52 R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b31820000 R11: 0000000000000246 R12: 00007ffc5c5b8e70
R13: 00007f5e4697dfac R14: 000000000004fcef R15: 00007f5e4697dfa0
 </TASK>

Showing all locks held in the system:
5 locks held by kworker/u4:0/9:
 #0: 
ffff888016c79138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90000ce7d00 ((work_completion)(&rdev->wiphy_work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff888073f08688 (&rdev->wiphy.mtx){+.+.}-{3:3}, at: wiphy_lock include/net/cfg80211.h:5319 [inline]
 #2: ffff888073f08688 (&rdev->wiphy.mtx){+.+.}-{3:3}, at: cfg80211_wiphy_work+0x31/0x260 net/wireless/core.c:420
 #3: ffff888023104d40 (&wdev->mtx){+.+.}-{3:3}, at: sdata_lock net/mac80211/ieee80211_i.h:1036 [inline]
 #3: ffff888023104d40 (&wdev->mtx){+.+.}-{3:3}, at: ieee80211_ibss_work+0xa8/0x10e0 net/mac80211/ibss.c:1685
 #4: ffff888073f09810 (&local->sta_mtx){+.+.}-{3:3}, at: ieee80211_ibss_sta_expire net/mac80211/ibss.c:1259 [inline]
 #4: ffff888073f09810 (&local->sta_mtx){+.+.}-{3:3}, at: ieee80211_sta_merge_ibss net/mac80211/ibss.c:1302 [inline]
 #4: ffff888073f09810 (&local->sta_mtx){+.+.}-{3:3}, at: ieee80211_ibss_work+0x571/0x10e0 net/mac80211/ibss.c:1713
6 locks held by kworker/0:1/13:
1 lock held by khungtaskd/27:
 #0: 
ffffffff8c31f320
 (rcu_read_lock
){....}-{1:2}
, at: rcu_lock_acquire+0x0/0x30
1 lock held by khugepaged/33:
 #0: 
ffffffff8c3b4cc8 (lock#4){+.+.}-{3:3}, at: __lru_add_drain_all+0x68/0xac0 mm/swap.c:782
2 locks held by kworker/u4:3/155:
 #0: ffff888016c79138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90002027d00 (connector_reaper_work){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
4 locks held by kworker/u4:5/3090:
 #0: ffff888016dcd938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc9000d90fd00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffffffff8d431cd0 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x148/0xba0 net/core/net_namespace.c:589
 #3: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: cangw_pernet_exit+0xe/0x20 net/can/gw.c:1279
2 locks held by getty/3950:
 #0: ffff88814d07c098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc900025e62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5df/0x1a70 drivers/tty/n_tty.c:2158
4 locks held by udevd/4179:
 #0: ffff888071c118b8 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xad/0xd50 fs/seq_file.c:182
 #1: ffff88801db59488
 (&of->mutex){+.+.}-{3:3}, at: kernfs_seq_start+0x51/0x3c0 fs/kernfs/file.c:112
 #2: ffff8880233d41d8 (kn->active#117){++++}-{0:0}, at: kernfs_seq_start+0x71/0x3c0 fs/kernfs/file.c:113
 #3: ffff88807766c220 (&dev->mutex){....}-{3:3}, at: device_lock_interruptible include/linux/device.h:769 [inline]
 #3: ffff88807766c220 (&dev->mutex){....}-{3:3}, at: manufacturer_show+0x22/0x90 drivers/usb/core/sysfs.c:141
1 lock held by syz-executor/4204:
 #0: 
ffffffff8c323da8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
ffffffff8c323da8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3a5/0x750 kernel/rcu/tree_exp.h:845
3 locks held by kworker/1:7/4264:
 #0: 
ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90004a4fd00
 (deferred_process_work){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: switchdev_deferred_process_work+0xa/0x20 net/switchdev/switchdev.c:74
2 locks held by kworker/u4:6/4271:
 #0: ffff888016c79138
 ((wq_completion)events_unbound
){+.+.}-{0:0}
, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc900011ffd00 ((reaper_work).work){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
2 locks held by kworker/u4:10/4320:
2 locks held by syz.0.564/6568:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:699 [inline]
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3440
 #1: ffffffff8c323da8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
 #1: ffffffff8c323da8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2d1/0x750 kernel/rcu/tree_exp.h:845
1 lock held by syz.3.572/6589:
 #0: ffffffff8c1e0948 (sched_core_mutex){+.+.}-{3:3}, at: sched_core_get+0x49/0x1d0 kernel/sched/core.c:329
1 lock held by syz-executor/6592:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}
, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5684
1 lock held by syz-executor/6595:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5684
1 lock held by syz-executor/6598:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5684
1 lock held by syz-executor/6601:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5684
1 lock held by syz-executor/6604:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5684
1 lock held by dhcpcd/6606:
 #0: ffff888076e36120 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1744 [inline]
 #0: ffff888076e36120 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x35/0xda0 net/packet/af_packet.c:3213
1 lock held by dhcpcd/6607:
 #0: ffff8880520e2120 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1744 [inline]
 #0: ffff8880520e2120 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x35/0xda0 net/packet/af_packet.c:3213
1 lock held by dhcpcd/6608:
 #0: ffff888076e32120 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1744 [inline]
 #0: ffff888076e32120 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x35/0xda0 net/packet/af_packet.c:3213
1 lock held by dhcpcd/6609:
 #0: ffff888076e30120 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1744 [inline]
 #0: ffff888076e30120 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x35/0xda0 net/packet/af_packet.c:3213
1 lock held by dhcpcd/6610:
 #0: ffff88801f01e120 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1744 [inline]
 #0: ffff88801f01e120 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x35/0xda0 net/packet/af_packet.c:3213
1 lock held by dhcpcd/6611:
 #0: ffff88801f01c120
 (sk_lock-AF_PACKET
){+.+.}-{0:0}
, at: lock_sock include/net/sock.h:1744 [inline]
, at: packet_do_bind+0x35/0xda0 net/packet/af_packet.c:3213
1 lock held by syz-executor/6613:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5684
1 lock held by syz-executor/6617:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5684
1 lock held by syz-executor/6618:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5684
1 lock held by syz-executor/6623:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5684
1 lock held by syz-executor/6626:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5684
1 lock held by syz-executor/6629:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5684
1 lock held by syz-executor/6633:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5684
1 lock held by syz-executor/6635:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5684
1 lock held by syz-executor/6638:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5684
1 lock held by syz-executor/6641:
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43dbc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5684

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

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe0f/0xe50 kernel/hung_task.c:369
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 13 Comm: kworker/0:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: usb_hub_wq hub_event
RIP: 0010:mark_held_locks kernel/locking/lockdep.c:4185 [inline]
RIP: 0010:__trace_hardirqs_on_caller kernel/locking/lockdep.c:4211 [inline]
RIP: 0010:lockdep_hardirqs_on_prepare+0x231/0x770 kernel/locking/lockdep.c:4278
Code: 00 00 45 31 ed 49 83 fd 31 73 67 4c 89 e0 48 c1 e8 03 0f b6 04 10 84 c0 75 76 41 8b 47 20 a9 00 00 04 00 74 2f 25 00 00 03 00 <83> f8 01 ba 03 00 00 00 83 da 00 48 8b 7c 24 10 4c 89 fe e8 c7 eb
RSP: 0018:ffffc90000007a20 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff88813fe28ae8 RCX: 7e82d6c00de8d400
RDX: dffffc0000000000 RSI: ffffffff8a2b3f00 RDI: ffffffff8a7a0700
RBP: ffffc90000007ae0 R08: ffffffff8d1e5fc3 R09: 1ffffffff1a3cbf8
R10: dffffc0000000000 R11: fffffbfff1a3cbf9 R12: ffff88813fe28b10
R13: 0000000000000000 R14: 1ffff11027fc515d R15: ffff88813fe28af0
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d4d7673f70 CR3: 000000002aa98000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 trace_hardirqs_on+0x67/0x80 kernel/trace/trace_preemptirq.c:49
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
 _raw_spin_unlock_irqrestore+0x82/0x120 kernel/locking/spinlock.c:194
 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
 expire_timers kernel/time/timer.c:1699 [inline]
 __run_timers+0x53e/0x800 kernel/time/timer.c:1970
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
 handle_softirqs+0x339/0x830 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:console_trylock_spinning+0x301/0x370 kernel/printk/printk.c:1909
Code: 85 db 74 89 e8 10 ea 18 00 fb 31 c0 eb 48 e8 06 ea 18 00 e8 a1 7d 5c 08 48 85 db 74 d1 e8 f7 e9 18 00 fb 48 c7 c7 60 3e 31 8c <31> f6 ba 01 00 00 00 31 c9 41 b8 01 00 00 00 45 31 c9 68 1a 4c 60
RSP: 0018:ffffc90000d263e0 EFLAGS: 00000246
RAX: ffffffff81604c19 RBX: 0000000000000200 RCX: 0000000000100000
RDX: ffffc90013df9000 RSI: 00000000000fffff RDI: ffffffff8c313e60
RBP: ffffc90000d264b0 R08: ffffffff901d6217 R09: 1ffffffff203ac42
R10: dffffc0000000000 R11: fffffbfff203ac43 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 1ffff920001a4c7c
 vprintk_emit+0xa7/0x150 kernel/printk/printk.c:2273
 dev_vprintk_emit+0x2e1/0x380 drivers/base/core.c:4638
 dev_printk_emit+0xeb/0x140 drivers/base/core.c:4649
 _dev_err+0x11b/0x170 drivers/base/core.c:4704
 parse_uac2_sample_rate_range+0x992/0xc60 sound/usb/format.c:401
 parse_audio_format_rates_v2v3+0x3c7/0x16c0 sound/usb/format.c:636
 parse_audio_format_i+0x74c/0xe80 sound/usb/format.c:718
 snd_usb_parse_audio_format+0x87/0x740 sound/usb/format.c:796
 snd_usb_get_audioformat_uac12 sound/usb/stream.c:854 [inline]
 __snd_usb_parse_audio_interface+0x18b1/0x4b00 sound/usb/stream.c:1196
 snd_usb_parse_audio_interface+0x36/0xb0 sound/usb/stream.c:1274
 create_standard_audio_quirk+0x59/0x120 sound/usb/quirks.c:100
 snd_usb_create_quirk sound/usb/quirks.c:577 [inline]
 create_composite_quirk+0x1ec/0x4e0 sound/usb/quirks.c:48
 usb_audio_probe+0xb97/0x1d90 sound/usb/card.c:885
 usb_probe_interface+0x5c5/0xb20 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x284/0xc80 drivers/base/dd.c:595
 __driver_probe_device+0x18c/0x330 drivers/base/dd.c:755
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:785
 __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:907
 bus_for_each_drv+0x184/0x210 drivers/base/bus.c:429
 __device_attach+0x2a8/0x480 drivers/base/dd.c:979
 bus_probe_device+0xbc/0x1e0 drivers/base/bus.c:489
 device_add+0xa00/0xfb0 drivers/base/core.c:3412
 usb_set_configuration+0x1991/0x1fd0 drivers/usb/core/message.c:2223
 usb_generic_driver_probe+0x89/0x150 drivers/usb/core/generic.c:238
 usb_probe_device+0x139/0x270 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x284/0xc80 drivers/base/dd.c:595
 __driver_probe_device+0x18c/0x330 drivers/base/dd.c:755
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:785
 __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:907
 bus_for_each_drv+0x184/0x210 drivers/base/bus.c:429
 __device_attach+0x2a8/0x480 drivers/base/dd.c:979
 bus_probe_device+0xbc/0x1e0 drivers/base/bus.c:489
 device_add+0xa00/0xfb0 drivers/base/core.c:3412
 usb_new_device+0xd65/0x1660 drivers/usb/core/hub.c:2632
 hub_port_connect drivers/usb/core/hub.c:5497 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5637 [inline]
 port_event drivers/usb/core/hub.c:5799 [inline]
 hub_event+0x2e4a/0x55e0 drivers/usb/core/hub.c:5881
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/22 11:02 linux-5.15.y 93741761e5e3 70ae9b03 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in __lru_add_drain_all
2026/05/17 05:37 linux-5.15.y 93741761e5e3 de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in __lru_add_drain_all
2026/05/14 10:54 linux-5.15.y de8dfb3f0278 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in __lru_add_drain_all
2026/05/13 04:55 linux-5.15.y de8dfb3f0278 a0949470 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in __lru_add_drain_all
2026/05/01 08:27 linux-5.15.y ef251c45f1cd 753c55b9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in __lru_add_drain_all
* Struck through repros no longer work on HEAD.