INFO: task modprobe:4551 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:modprobe state:D stack:24352 pid:4551 ppid:29 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5244 [inline] __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561 schedule+0xb9/0x180 kernel/sched/core.c:6637 rwsem_down_write_slowpath+0xbed/0x1090 kernel/locking/rwsem.c:1189 mmap_write_lock include/linux/mmap_lock.h:71 [inline] exit_mmap+0x20f/0x8e0 mm/mmap.c:3258 __mmput+0x118/0x3c0 kernel/fork.c:1200 exit_mm+0x1e6/0x2c0 kernel/exit.c:565 do_exit+0x8c1/0x2400 kernel/exit.c:867 do_group_exit+0x217/0x2d0 kernel/exit.c:1022 __do_sys_exit_group kernel/exit.c:1033 [inline] __se_sys_exit_group kernel/exit.c:1031 [inline] __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1031 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f9bdd4cf6c5 RSP: 002b:00007ffeb2109378 EFLAGS: 00000206 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007f9bdd5d0fe8 RCX: 00007f9bdd4cf6c5 RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000001 RBP: 0000000000000001 R08: 00007ffeb2109308 R09: 0000000000000000 R10: 00007ffeb21091a0 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000001 R14: 00007f9bdd5cf680 R15: 00007f9bdd5d1000 INFO: task syz.0.31:4557 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.0.31 state:D stack:25696 pid:4557 ppid:4399 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5244 [inline] __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561 schedule+0xb9/0x180 kernel/sched/core.c:6637 rwsem_down_write_slowpath+0xbed/0x1090 kernel/locking/rwsem.c:1189 mmap_write_lock include/linux/mmap_lock.h:71 [inline] exit_mmap+0x20f/0x8e0 mm/mmap.c:3258 __mmput+0x118/0x3c0 kernel/fork.c:1200 exit_mm+0x1e6/0x2c0 kernel/exit.c:565 do_exit+0x8c1/0x2400 kernel/exit.c:867 do_group_exit+0x217/0x2d0 kernel/exit.c:1022 __do_sys_exit_group kernel/exit.c:1033 [inline] __se_sys_exit_group kernel/exit.c:1031 [inline] __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1031 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f2548b8f749 RSP: 002b:00007ffc0e867738 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f2548b8f749 RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007ffc0e86779c R08: 000000050e86782f R09: 00000000000927c0 R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000009 R13: 00000000000927c0 R14: 000000000002cac5 R15: 00007ffc0e8677f0 Showing all locks held in the system: 1 lock held by rcu_tasks_kthre/12: #0: ffffffff8cb2b630 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517 1 lock held by rcu_tasks_trace/13: #0: ffffffff8cb2be50 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517 1 lock held by khungtaskd/28: #0: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #0: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #0: ffffffff8cb2aca0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513 2 locks held by kworker/u4:2/29: #0: ffff888017479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267 #1: ffffc90000a5fd00 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267 1 lock held by dhcpcd/3933: #0: ffffffff8cb538d0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: copy_process+0x248b/0x4020 kernel/fork.c:2446 2 locks held by getty/4027: #0: ffff8880304d9098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41b/0x1380 drivers/tty/n_tty.c:2198 1 lock held by udevd/4308: #0: ffffffff8cb538d0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: do_exit+0x578/0x2400 kernel/exit.c:827 1 lock held by udevd/4329: #0: ffffffff8cb538d0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: do_exit+0x578/0x2400 kernel/exit.c:827 1 lock held by udevd/4330: #0: ffffffff8cb538d0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: do_exit+0x578/0x2400 kernel/exit.c:827 1 lock held by udevd/4332: #0: ffffffff8cb538d0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: do_exit+0x578/0x2400 kernel/exit.c:827 1 lock held by udevd/4334: #0: ffffffff8cb538d0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: do_exit+0x578/0x2400 kernel/exit.c:827 1 lock held by syz-executor/4397: #0: ffffffff8cb538d0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: do_exit+0x578/0x2400 kernel/exit.c:827 2 locks held by syz-executor/4406: #0: ffffffff8cbc5010 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mmap kernel/fork.c:593 [inline] #0: ffffffff8cbc5010 (dup_mmap_sem){.+.+}-{0:0}, at: dup_mm kernel/fork.c:1541 [inline] #0: ffffffff8cbc5010 (dup_mmap_sem){.+.+}-{0:0}, at: copy_mm+0x2a9/0x15c0 kernel/fork.c:1590 #1: ffff888025ca08d8 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline] #1: ffff888025ca08d8 (&mm->mmap_lock){++++}-{3:3}, at: dup_mmap kernel/fork.c:594 [inline] #1: ffff888025ca08d8 (&mm->mmap_lock){++++}-{3:3}, at: dup_mm kernel/fork.c:1541 [inline] #1: ffff888025ca08d8 (&mm->mmap_lock){++++}-{3:3}, at: copy_mm+0x2c3/0x15c0 kernel/fork.c:1590 7 locks held by syz-executor/4407: #0: ffff88802457a460 (sb_writers#11){.+.+}-{0:0}, at: vfs_write+0x256/0x960 fs/read_write.c:580 #1: ffff888076bb4c88 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1e3/0x520 fs/kernfs/file.c:343 #2: ffffffff8cb536e8 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_lock include/linux/cgroup.h:442 [inline] #2: ffffffff8cb536e8 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_kn_lock_live+0xee/0x230 kernel/cgroup/cgroup.c:1700 #3: ffffffff8c9c7b30 (cpu_hotplug_lock){++++}-{0:0}, at: cgroup_attach_lock kernel/cgroup/cgroup.c:2476 [inline] #3: ffffffff8c9c7b30 (cpu_hotplug_lock){++++}-{0:0}, at: cgroup_procs_write_start+0x183/0x600 kernel/cgroup/cgroup.c:2982 #4: ffffffff8cb538d0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: cgroup_attach_lock kernel/cgroup/cgroup.c:2478 [inline] #4: ffffffff8cb538d0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: cgroup_procs_write_start+0x199/0x600 kernel/cgroup/cgroup.c:2982 #5: ffffffff8cb61d68 (cpuset_mutex){+.+.}-{3:3}, at: cpuset_attach+0xac/0x540 kernel/cgroup/cpuset.c:2647 #6: ffff8880303a0158 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline] #6: ffff8880303a0158 (&mm->mmap_lock){++++}-{3:3}, at: mpol_rebind_mm+0xbe/0x370 mm/mempolicy.c:386 1 lock held by syz-executor/4411: #0: ffffffff8cb538d0 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: copy_process+0x248b/0x4020 kernel/fork.c:2446 1 lock held by modprobe/4551: #0: ffff88801746a6d8 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline] #0: ffff88801746a6d8 (&mm->mmap_lock){++++}-{3:3}, at: exit_mmap+0x20f/0x8e0 mm/mmap.c:3258 1 lock held by syz.0.31/4557: #0: ffff888018ecbd58 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline] #0: ffff888018ecbd58 (&mm->mmap_lock){++++}-{3:3}, at: exit_mmap+0x20f/0x8e0 mm/mmap.c:3258 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 28 Comm: khungtaskd Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Call Trace: dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106 nmi_cpu_backtrace+0x3f4/0x470 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline] watchdog+0xeee/0xf30 kernel/hung_task.c:377 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 11 Comm: kworker/u4:1 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Workqueue: events_unbound toggle_allocation_gate RIP: 0010:lookup_chain_cache kernel/locking/lockdep.c:3719 [inline] RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:3738 [inline] RIP: 0010:validate_chain kernel/locking/lockdep.c:3793 [inline] RIP: 0010:__lock_acquire+0x1705/0x7c50 kernel/locking/lockdep.c:5049 Code: 00 48 8b 7c 24 28 48 8b 74 24 20 48 ba 00 00 00 00 00 fc ff df e9 65 ff ff ff 4c 8d 73 18 4c 89 f0 48 c1 e8 03 42 80 3c 00 00 <74> 12 4c 89 f7 e8 e1 f0 6d 00 49 b8 00 00 00 00 00 fc ff df 49 8b RSP: 0018:ffffc900001074e0 EFLAGS: 00000046 RAX: 1ffffffff215cb83 RBX: ffffffff90ae5c00 RCX: ffffffff81631100 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90ae2240 RBP: ffffc90000107730 R08: dffffc0000000000 R09: fffffbfff215c449 R10: fffffbfff215c449 R11: 1ffffffff215c448 R12: ffffffff90751968 R13: 0000000075a1531d R14: ffffffff90ae5c18 R15: ffff88813fe7c650 FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f678254a4c0 CR3: 000000000c88e000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162 debug_object_assert_init+0x98/0x2f0 lib/debugobjects.c:887 debug_timer_assert_init kernel/time/timer.c:792 [inline] debug_assert_init kernel/time/timer.c:837 [inline] __mod_timer+0x54/0xd00 kernel/time/timer.c:1020 queue_delayed_work_on+0x126/0x1e0 kernel/workqueue.c:1704 queue_delayed_work include/linux/workqueue.h:527 [inline] toggle_allocation_gate+0x3d6/0x430 mm/kfence/core.c:821 process_one_work+0x898/0x1160 kernel/workqueue.c:2292 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295