syzbot


INFO: task hung in do_epoll_ctl_file

Status: upstream: reported C repro on 2026/05/28 10:34
Subsystems: kernfs
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+f83fa2cf571bd7650422@syzkaller.appspotmail.com
First crash: 25d, last: 10d
Cause bisection: failed (error log, bisect log)
  
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ID Workflow Result Correct Bug Created Started Finished Revision Error
ed3b1fb5-1f04-49c1-a455-979b02cce4db assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ INFO: task hung in do_epoll_ctl_file 2026/06/01 20:15 2026/06/01 20:15 2026/06/01 21:17 386cc6dacdf7e3ebce9507beed6755d7e999554d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kernfs?] INFO: task hung in do_epoll_ctl_file 0 (2) 2026/05/28 13:34
Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/05/28 13:34 25m kartikey406@gmail.com patch linux-next log

Sample crash report:
INFO: tas[  358.361221][   T39] INFO: task syz.1.18:6030 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.18        state:D stack:26808 pid:6030  tgid:6030  ppid:5779   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5402 [inline]
 __schedule+0x16f9/0x5500 kernel/sched/core.c:7204
 __schedule_loop kernel/sched/core.c:7283 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7579
 rt_mutex_slowlock_block+0x508/0x680 kernel/locking/rtmutex.c:1666
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1743 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1783 [inline]
 rt_mutex_slowlock+0x2dc/0x780 kernel/locking/rtmutex.c:1823
 __rt_mutex_lock kernel/locking/rtmutex.c:1838 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:560 [inline]
 mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:578
 epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 ep_ctl_lock fs/eventpoll.c:2559 [inline]
 do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
 do_epoll_ctl fs/eventpoll.c:2698 [inline]
 __do_sys_epoll_ctl fs/eventpoll.c:2715 [inline]
 __se_sys_epoll_ctl+0x14e/0x210 fs/eventpoll.c:2706
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa0ef9ece59
RSP: 002b:00007ffe81e0f328 EFLAGS: 00000246 ORIG_RAX: 00000000000000e9
RAX: ffffffffffffffda RBX: 00007fa0efc65fa0 RCX: 00007fa0ef9ece59
RDX: 0000000000000004 RSI: 0000000000000001 RDI: 0000000000000005
RBP: 00007fa0efa82d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000200000000100 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa0efc65fac R14: 00007fa0efc65fa0 R15: 00007fa0efc65fa0
 </TASK>
INFO: task syz.2.19:6031 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.19        state:D stack:26808 pid:6031  tgid:6031  ppid:5786   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5402 [inline]
 __schedule+0x16f9/0x5500 kernel/sched/core.c:7204
 __schedule_loop kernel/sched/core.c:7283 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7579
 rt_mutex_slowlock_block+0x508/0x680 kernel/locking/rtmutex.c:1666
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1743 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1783 [inline]
 rt_mutex_slowlock+0x2dc/0x780 kernel/locking/rtmutex.c:1823
 __rt_mutex_lock kernel/locking/rtmutex.c:1838 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:560 [inline]
 mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:578
 epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 ep_ctl_lock fs/eventpoll.c:2559 [inline]
 do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
 do_epoll_ctl fs/eventpoll.c:2698 [inline]
 __do_sys_epoll_ctl fs/eventpoll.c:2715 [inline]
 __se_sys_epoll_ctl+0x14e/0x210 fs/eventpoll.c:2706
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4ea623ce59
RSP: 002b:00007ffc16d0ea78 EFLAGS: 00000246 ORIG_RAX: 00000000000000e9
RAX: ffffffffffffffda RBX: 00007f4ea64b5fa0 RCX: 00007f4ea623ce59
RDX: 0000000000000004 RSI: 0000000000000001 RDI: 0000000000000005
RBP: 00007f4ea62d2d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000200000000100 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4ea64b5fac R14: 00007f4ea64b5fa0 R15: 00007f4ea64b5fa0
 </TASK>
INFO: task syz.0.17:6032 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17        state:D stack:26808 pid:6032  tgid:6032  ppid:5782   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5402 [inline]
 __schedule+0x16f9/0x5500 kernel/sched/core.c:7204
 __schedule_loop kernel/sched/core.c:7283 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7579
 rt_mutex_slowlock_block+0x508/0x680 kernel/locking/rtmutex.c:1666
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1743 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1783 [inline]
 rt_mutex_slowlock+0x2dc/0x780 kernel/locking/rtmutex.c:1823
 __rt_mutex_lock kernel/locking/rtmutex.c:1838 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:560 [inline]
 mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:578
 epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 ep_ctl_lock fs/eventpoll.c:2559 [inline]
 do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
 do_epoll_ctl fs/eventpoll.c:2698 [inline]
 __do_sys_epoll_ctl fs/eventpoll.c:2715 [inline]
 __se_sys_epoll_ctl+0x14e/0x210 fs/eventpoll.c:2706
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc5b492ce59
RSP: 002b:00007ffcdf2d99c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e9
RAX: ffffffffffffffda RBX: 00007fc5b4ba5fa0 RCX: 00007fc5b492ce59
RDX: 0000000000000004 RSI: 0000000000000001 RDI: 0000000000000005
RBP: 00007fc5b49c2d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000200000000100 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc5b4ba5fac R14: 00007fc5b4ba5fa0 R15: 00007fc5b4ba5fa0
 </TASK>
INFO: task syz.4.21:6033 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.21        state:D stack:26808 pid:6033  tgid:6033  ppid:5790   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5402 [inline]
 __schedule+0x16f9/0x5500 kernel/sched/core.c:7204
 __schedule_loop kernel/sched/core.c:7283 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7579
 rt_mutex_slowlock_block+0x508/0x680 kernel/locking/rtmutex.c:1666
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1743 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1783 [inline]
 rt_mutex_slowlock+0x2dc/0x780 kernel/locking/rtmutex.c:1823
 __rt_mutex_lock kernel/locking/rtmutex.c:1838 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:560 [inline]
 mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:578
 epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 ep_ctl_lock fs/eventpoll.c:2559 [inline]
 do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
 do_epoll_ctl fs/eventpoll.c:2698 [inline]
 __do_sys_epoll_ctl fs/eventpoll.c:2715 [inline]
 __se_sys_epoll_ctl+0x14e/0x210 fs/eventpoll.c:2706
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3f07c9ce59
RSP: 002b:00007ffc9dc2e578 EFLAGS: 00000246 ORIG_RAX: 00000000000000e9
RAX: ffffffffffffffda RBX: 00007f3f07f15fa0 RCX: 00007f3f07c9ce59
RDX: 0000000000000004 RSI: 0000000000000001 RDI: 0000000000000005
RBP: 00007f3f07d32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000200000000100 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3f07f15fac R14: 00007f3f07f15fa0 R15: 00007f3f07f15fa0
 </TASK>

Showing all locks held in the system:
6 locks held by ktimers/1/30:
 #0: ffffffff8de61600 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
 #1: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
 #2: ffff8880b8726220 (&base->expiry_lock){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #2: ffff8880b8726220 (&base->expiry_lock){+...}-{3:3}, at: timer_base_lock_expiry kernel/time/timer.c:1502 [inline]
 #2: ffff8880b8726220 (&base->expiry_lock){+...}-{3:3}, at: __run_timer_base+0x120/0x9f0 kernel/time/timer.c:2384
 #3: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #3: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #3: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #3: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57
 #4: ffffc90000a4fa80 ((&ndev->rs_timer)){+...}-{0:0}, at: call_timer_fn+0xd4/0x5e0 kernel/time/timer.c:1745
 #5: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #5: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #5: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: ndisc_send_skb+0x215/0x1670 net/ipv6/ndisc.c:482
1 lock held by khungtaskd/39:
 #0: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #0: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6777
8 locks held by kworker/u8:4/67:
 #0: ffff88813fe84138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x897/0x1630 kernel/workqueue.c:3293
 #1: ffffc9000152fc40 ((work_completion)(&rdev->wiphy_work)){+.+.}-{0:0}, at: process_one_work+0x8be/0x1630 kernel/workqueue.c:3294
 #2: ffff8880626608d8 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6885 [inline]
 #2: ffff8880626608d8 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: cfg80211_wiphy_work+0xb4/0x460 net/wireless/core.c:524
 #3: ffffffff8de61600 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
 #4: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
 #5: ffff888062660228 (&rdev->bss_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock_rt.h:90 [inline]
 #5: ffff888062660228 (&rdev->bss_lock){+...}-{3:3}, at: cfg80211_inform_single_bss_data+0xbbf/0x1b80 net/wireless/scan.c:2367
 #6: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #6: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #6: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #6: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57
 #7: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #7: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #7: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1181 [inline]
 #7: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0xa6/0x2550 arch/x86/kernel/unwind_orc.c:495
6 locks held by kworker/u8:7/405:
 #0: ffff88813fe84138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x897/0x1630 kernel/workqueue.c:3293
 #1: ffffc9000419fc40 ((work_completion)(&rdev->wiphy_work)){+.+.}-{0:0}, at: process_one_work+0x8be/0x1630 kernel/workqueue.c:3294
 #2: ffff8880566c08d8 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6885 [inline]
 #2: ffff8880566c08d8 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: cfg80211_wiphy_work+0xb4/0x460 net/wireless/core.c:524
 #3: ffffffff8de61600 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
 #4: ffffffff8dfcabc0 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
 #5: ffff8880566c0228 (&rdev->bss_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock_rt.h:90 [inline]
 #5: ffff8880566c0228 (&rdev->bss_lock){+...}-{3:3}, at: cfg80211_put_bss+0x5b/0x270 net/wireless/scan.c:3347
4 locks held by kworker/u8:8/1024:
 #0: ffff88813fe84138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x897/0x1630 kernel/workqueue.c:3293
 #1: ffffc90005c67c40 ((work_completion)(&rdev->wiphy_work)){+.+.}-{0:0}, at: process_one_work+0x8be/0x1630 kernel/workqueue.c:3294
 #2: ffff8880634908d8 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6885 [inline]
 #2: ffff8880634908d8 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: cfg80211_wiphy_work+0xb4/0x460 net/wireless/core.c:524
 #3: ffffffff8de61600 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
2 locks held by getty/5375:
 #0: ffff8880361670a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003cc62e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13a0 drivers/tty/n_tty.c:2211
2 locks held by syz.3.20/6016:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
 #1: ffff888028754058 (&ep->mtx){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #1: ffff888028754058 (&ep->mtx){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2573 [inline]
 #1: ffff888028754058 (&ep->mtx){+.+.}-{4:4}, at: do_epoll_ctl_file+0xc69/0xed0 fs/eventpoll.c:2636
1 lock held by syz.1.18/6030:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.2.19/6031:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.0.17/6032:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.4.21/6033:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.5.22/6168:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.6.23/6240:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.7.24/6241:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.8.25/6245:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.9.26/6246:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.3.27/6289:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.1.28/6406:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.2.29/6467:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.0.30/6476:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.4.31/6481:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.5.32/6482:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.6.33/6535:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.7.34/6704:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.8.35/6724:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.9.36/6735:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.3.37/6737:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
1 lock held by syz.1.38/6739:
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline]
 #0: ffffffff8e157958 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636
2 locks held by syz-executor/6744:
 #0: ffffffff8eae37a8 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8eae37a8 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #0: ffffffff8eae37a8 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f37fa78 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f37fa78 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f37fa78 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x883/0x1bb0 net/core/rtnetlink.c:4122

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

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 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:119
 nmi_trigger_cpumask_backtrace+0x17a/0x380 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [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:353 [inline]
 watchdog+0xfd3/0x1030 kernel/hung_task.c:561
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 17 Comm: pr/legacy Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:rdtsc_ordered arch/x86/include/asm/tsc.h:57 [inline]
RIP: 0010:delay_tsc+0x71/0xc0 arch/x86/lib/delay.c:72
Code: 00 00 e8 b2 4a 68 f6 65 8b 05 eb c5 47 07 85 c0 74 1c f3 90 bf 01 00 00 00 e8 fb 48 68 f6 e8 76 86 01 00 39 c5 75 0e 0f 01 f9 <66> 90 eb bd e8 f6 c0 07 f6 eb dd 4c 29 fb e8 5c 86 01 00 89 c5 0f
RSP: 0018:ffffc900001679d0 EFLAGS: 00000246
RAX: 00000000499b963d RBX: 0000000000000899 RCX: 0000000000000001
RDX: 00000000000000ba RSI: ffffffff8ba9cd60 RDI: ffffffff8ba9cd20
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff8b2b79f0 R12: 1ffffffff3374446
R13: 00000000ffffffff R14: 000000ba499b91db R15: 000000000000038d
FS:  0000000000000000(0000) GS:ffff888125fec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc83a6dee9c CR3: 00000000352e2000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 udelay include/asm-generic/delay.h:62 [inline]
 wait_for_lsr+0x166/0x2f0 drivers/tty/serial/8250/8250_port.c:1981
 serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3212 [inline]
 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3277 [inline]
 serial8250_console_write+0x11c9/0x1b90 drivers/tty/serial/8250/8250_port.c:3362
 console_emit_next_record kernel/printk/printk.c:3163 [inline]
 console_flush_one_record+0x68b/0xb90 kernel/printk/printk.c:3269
 legacy_kthread_func+0x1b6/0x250 kernel/printk/printk.c:3712
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (10):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/24 10:21 linux-next c1ecb239fa34 c69befb3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in do_epoll_ctl_file
2026/06/03 07:17 linux-next f7af91adc230 3c0d2131 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in do_epoll_ctl_file
2026/05/31 14:57 linux-next f7af91adc230 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in do_epoll_ctl_file
2026/05/30 19:02 linux-next f7af91adc230 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in do_epoll_ctl_file
2026/05/29 14:21 linux-next f7af91adc230 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in do_epoll_ctl_file
2026/05/29 14:05 linux-next f7af91adc230 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in do_epoll_ctl_file
2026/05/29 12:53 linux-next f7af91adc230 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in do_epoll_ctl_file
2026/05/27 00:57 linux-next e7e28506af98 2b01f00e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in do_epoll_ctl_file
2026/05/24 07:01 linux-next c1ecb239fa34 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in do_epoll_ctl_file
2026/05/18 18:49 linux-next 80dd246accce 55156e84 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in do_epoll_ctl_file
* Struck through repros no longer work on HEAD.