INFO: task syz-executor:25519 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor state:D stack:24840 pid:25519 tgid:25519 ppid:1 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1480/0x50a0 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] rt_mutex_schedule+0x77/0xf0 kernel/sched/core.c:7241 rt_mutex_slowlock_block kernel/locking/rtmutex.c:1647 [inline] __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline] __rt_mutex_slowlock_locked+0x1dfe/0x25e0 kernel/locking/rtmutex.c:1760 __rwbase_read_lock+0xbc/0x180 kernel/locking/rwbase_rt.c:114 rwbase_read_lock kernel/locking/rwbase_rt.c:147 [inline] __down_read kernel/locking/rwsem.c:1466 [inline] down_read+0x127/0x1f0 kernel/locking/rwsem.c:1539 rdma_dev_init_net+0x22d/0x2f0 drivers/infiniband/core/device.c:1220 ops_init+0x35c/0x5c0 net/core/net_namespace.c:137 setup_net+0x110/0x330 net/core/net_namespace.c:446 copy_net_ns+0x3e3/0x570 net/core/net_namespace.c:581 create_new_namespaces+0x3e7/0x6a0 kernel/nsproxy.c:130 unshare_nsproxy_namespaces+0x11c/0x170 kernel/nsproxy.c:226 ksys_unshare+0x4c8/0x8c0 kernel/fork.c:3171 __do_sys_unshare kernel/fork.c:3242 [inline] __se_sys_unshare kernel/fork.c:3240 [inline] __x64_sys_unshare+0x38/0x50 kernel/fork.c:3240 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5ce88d0f47 RSP: 002b:00007ffd9268f748 EFLAGS: 00000206 ORIG_RAX: 0000000000000110 RAX: ffffffffffffffda RBX: 00007f5ce8b25f40 RCX: 00007f5ce88d0f47 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000 RBP: 00007f5ce8b267b8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000008 R13: 0000[ 1318.459070][ T38] R13: 0000000000000003 R14: 00007ffd9268fa18 R15: 0000000000000000 INFO: task syz-executor:25534 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor state:D stack:24648 pid:25534 tgid:25534 ppid:1 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1480/0x50a0 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] rt_mutex_schedule+0x77/0xf0 kernel/sched/core.c:7241 rt_mutex_slowlock_block kernel/locking/rtmutex.c:1647 [inline] __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline] __rt_mutex_slowlock_locked+0x1dfe/0x25e0 kernel/locking/rtmutex.c:1760 __rwbase_read_lock+0xbc/0x180 kernel/locking/rwbase_rt.c:114 rwbase_read_lock kernel/locking/rwbase_rt.c:147 [inline] __down_read kernel/locking/rwsem.c:1466 [inline] down_read+0x127/0x1f0 kernel/locking/rwsem.c:1539 rdma_dev_init_net+0x22d/0x2f0 drivers/infiniband/core/device.c:1220 ops_init+0x35c/0x5c0 net/core/net_namespace.c:137 setup_net+0x110/0x330 net/core/net_namespace.c:446 copy_net_ns+0x3e3/0x570 net/core/net_namespace.c:581 create_new_namespaces+0x3e7/0x6a0 kernel/nsproxy.c:130 unshare_nsproxy_namespaces+0x11c/0x170 kernel/nsproxy.c:226 ksys_unshare+0x4c8/0x8c0 kernel/fork.c:3171 __do_sys_unshare kernel/fork.c:3242 [inline] __se_sys_unshare kernel/fork.c:3240 [inline] __x64_sys_unshare+0x38/0x50 kernel/fork.c:3240 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f7158f80f47 RSP: 002b:00007ffdee702e28 EFLAGS: 00000202 ORIG_RAX: 0000000000000110 RAX: ffffffffffffffda RBX: 00007f71591d5f40 RCX: 00007f7158f80f47 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000 RBP: 00007f71591d67b8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008 R13: 0000000000000003 R14: 00007ffdee7030f8 R15: 0000000000000000 Showing all locks held in the system: 7 locks held by ksoftirqd/0/15: 4 locks held by ktimers/1/29: 1 lock held by khungtaskd/38: #0: ffffffff8d5ae880 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8d5ae880 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #0: ffffffff8d5ae880 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775 3 locks held by kworker/0:2/192: #0: ffff8881436bc538 ((wq_completion)infiniband){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline] #0: ffff8881436bc538 ((wq_completion)infiniband){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x1770 kernel/workqueue.c:3340 #1: ffffc90003bb7b80 ((work_completion)(&work->work)#3){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline] #1: ffffc90003bb7b80 ((work_completion)(&work->work)#3){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x1770 kernel/workqueue.c:3340 #2: ffff888038b1d430 (&rxe->usdev_lock){+.+.}-{4:4}, at: rxe_query_port+0x7e/0x3d0 drivers/infiniband/sw/rxe/rxe_verbs.c:61 3 locks held by kworker/u8:18/4005: #0: ffff88813ff69938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline] #0: ffff88813ff69938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x1770 kernel/workqueue.c:3340 #1: ffffc9000d5e7b80 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline] #1: ffffc9000d5e7b80 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x1770 kernel/workqueue.c:3340 #2: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:303 4 locks held by kworker/u8:19/4137: #0: ffff888019ad4938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline] #0: ffff888019ad4938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x1770 kernel/workqueue.c:3340 #1: ffffc9000d977b80 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline] #1: ffffc9000d977b80 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x1770 kernel/workqueue.c:3340 #2: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf7/0x7b0 net/core/net_namespace.c:670 #3: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: default_device_exit_batch+0xdc/0x9e0 net/core/dev.c:13022 1 lock held by dhcpcd/5466: #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x3b0/0x18b0 net/ipv4/devinet.c:978 2 locks held by getty/5563: #0: ffff88803016f0a0 (&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+0x44f/0x1460 drivers/tty/n_tty.c:2211 3 locks held by kworker/u8:22/12836: #0: ffff88814d8c7938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline] #0: ffff88814d8c7938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x1770 kernel/workqueue.c:3340 #1: ffffc9000eaf7b80 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline] #1: ffffc9000eaf7b80 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x1770 kernel/workqueue.c:3340 #2: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #2: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x119/0x15a0 net/ipv6/addrconf.c:4194 2 locks held by syz-executor/24917: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: cfg802154_pernet_exit+0x19/0xe0 net/ieee802154/core.c:351 2 locks held by syz-executor/25173: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffff88804c475118 (&device->compat_devs_mutex){+.+.}-{4:4}, at: remove_one_compat_dev drivers/infiniband/core/device.c:1034 [inline] #1: ffff88804c475118 (&device->compat_devs_mutex){+.+.}-{4:4}, at: rdma_dev_exit_net+0x1ac/0x340 drivers/infiniband/core/device.c:1176 2 locks held by syz-executor/25192: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: default_device_exit_batch+0xdc/0x9e0 net/core/dev.c:13022 2 locks held by syz-executor/25228: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffff888038b1d118 (&device->compat_devs_mutex){+.+.}-{4:4}, at: remove_one_compat_dev drivers/infiniband/core/device.c:1034 [inline] #1: ffff888038b1d118 (&device->compat_devs_mutex){+.+.}-{4:4}, at: rdma_dev_exit_net+0x1ac/0x340 drivers/infiniband/core/device.c:1176 2 locks held by syz-executor/25265: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: wg_netns_pre_exit+0x1c/0x200 drivers/net/wireguard/device.c:419 2 locks held by syz-executor/25276: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffffffff8e5ff280 (rdma_nets_rwsem){++++}-{4:4}, at: rdma_dev_exit_net+0x8c/0x340 drivers/infiniband/core/device.c:1159 2 locks held by syz-executor/25290: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffffffff8e5ff280 (rdma_nets_rwsem){++++}-{4:4}, at: rdma_dev_exit_net+0x8c/0x340 drivers/infiniband/core/device.c:1159 4 locks held by syz-executor/25340: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffffffff8e5ff040 (devices_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x1f5/0x2f0 drivers/infiniband/core/device.c:1215 #2: ffffffff8e5ff280 (rdma_nets_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x22d/0x2f0 drivers/infiniband/core/device.c:1220 #3: ffff88804c475118 (&device->compat_devs_mutex){+.+.}-{4:4}, at: add_one_compat_dev+0xf0/0x650 drivers/infiniband/core/device.c:979 3 locks held by syz-executor/25370: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffffffff8e5ff040 (devices_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x1f5/0x2f0 drivers/infiniband/core/device.c:1215 #2: ffffffff8e5ff280 (rdma_nets_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x22d/0x2f0 drivers/infiniband/core/device.c:1220 5 locks held by syz-executor/25382: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffffffff8e5ff040 (devices_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x1f5/0x2f0 drivers/infiniband/core/device.c:1215 #2: ffffffff8e5ff280 (rdma_nets_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x22d/0x2f0 drivers/infiniband/core/device.c:1220 #3: ffff88804c475118 (&device->compat_devs_mutex){+.+.}-{4:4}, at: add_one_compat_dev+0xf0/0x650 drivers/infiniband/core/device.c:979 #4: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: ib_get_eth_speed+0x151/0x7b0 drivers/infiniband/core/verbs.c:1998 3 locks held by syz-executor/25406: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffffffff8e5ff040 (devices_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x1f5/0x2f0 drivers/infiniband/core/device.c:1215 #2: ffffffff8e5ff280 (rdma_nets_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x22d/0x2f0 drivers/infiniband/core/device.c:1220 4 locks held by syz-executor/25461: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffffffff8e5ff040 (devices_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x1f5/0x2f0 drivers/infiniband/core/device.c:1215 #2: ffffffff8e5ff280 (rdma_nets_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x22d/0x2f0 drivers/infiniband/core/device.c:1220 #3: ffff888038b1d118 (&device->compat_devs_mutex){+.+.}-{4:4}, at: add_one_compat_dev+0xf0/0x650 drivers/infiniband/core/device.c:979 6 locks held by syz-executor/25495: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffffffff8e5ff040 (devices_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x1f5/0x2f0 drivers/infiniband/core/device.c:1215 #2: ffffffff8e5ff280 (rdma_nets_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x22d/0x2f0 drivers/infiniband/core/device.c:1220 #3: ffff888038b1d118 (&device->compat_devs_mutex){+.+.}-{4:4}, at: add_one_compat_dev+0xf0/0x650 drivers/infiniband/core/device.c:979 #4: ffff888038b1d430 (&rxe->usdev_lock){+.+.}-{4:4}, at: rxe_query_port+0x7e/0x3d0 drivers/infiniband/sw/rxe/rxe_verbs.c:61 #5: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: ib_get_eth_speed+0x151/0x7b0 drivers/infiniband/core/verbs.c:1998 3 locks held by syz-executor/25519: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffffffff8e5ff040 (devices_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x1f5/0x2f0 drivers/infiniband/core/device.c:1215 #2: ffffffff8e5ff280 (rdma_nets_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x22d/0x2f0 drivers/infiniband/core/device.c:1220 3 locks held by syz-executor/25534: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffffffff8e5ff040 (devices_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x1f5/0x2f0 drivers/infiniband/core/device.c:1215 #2: ffffffff8e5ff280 (rdma_nets_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x22d/0x2f0 drivers/infiniband/core/device.c:1220 3 locks held by syz-executor/25577: #0: ffffffff8e88e320 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x3cc/0x570 net/core/net_namespace.c:577 #1: ffffffff8e5ff040 (devices_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x1f5/0x2f0 drivers/infiniband/core/device.c:1215 #2: ffffffff8e5ff280 (rdma_nets_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x22d/0x2f0 drivers/infiniband/core/device.c:1220 1 lock held by syz-executor/25635: #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x3b0/0x18b0 net/ipv4/devinet.c:978 1 lock held by syz-executor/25647: #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x3b0/0x18b0 net/ipv4/devinet.c:978 1 lock held by syz-executor/25673: #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x3b0/0x18b0 net/ipv4/devinet.c:978 1 lock held by syz-executor/25712: #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x3b0/0x18b0 net/ipv4/devinet.c:978 1 lock held by syz-executor/25766: #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x3b0/0x18b0 net/ipv4/devinet.c:978 1 lock held by syz-executor/25787: #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x3b0/0x18b0 net/ipv4/devinet.c:978 1 lock held by syz-executor/25809: #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x3b0/0x18b0 net/ipv4/devinet.c:978 1 lock held by syz-executor/25859: #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8e89b438 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x3b0/0x18b0 net/ipv4/devinet.c:978 4 locks held by syz.2.9244/25895: ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:160 [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+0xf95/0xfe0 kernel/hung_task.c:515 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 29 Comm: ktimers/1 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:preempt_count_add+0xc7/0x190 kernel/sched/core.c:5731 Code: 00 65 4c 8b 34 25 08 e0 b0 91 49 81 c6 68 15 00 00 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 bc 06 92 00 49 89 1e <5b> 41 5e 41 5f c3 cc cc cc cc cc 89 fb 90 e8 d6 c3 e9 02 85 c0 74 RSP: 0018:ffffc90000a3e900 EFLAGS: 00000002 RAX: 0000000000000002 RBX: ffffc90000a3e968 RCX: ffffffff98bc1403 RDX: 0000000000000001 RSI: 0000000000000008 RDI: 0000000000000001 RBP: ffffc90000a3e9d8 R08: ffff8880b8946637 R09: 1ffff11017128cc6 R10: dffffc0000000000 R11: ffffed1017128cc7 R12: 1ffff92000147d2d R13: 0000000000000a02 R14: ffff8880b89465e0 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff888126e12000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f260b436080 CR3: 000000000d3a8000 CR4: 00000000003526f0 Call Trace: class_preempt_constructor include/linux/preempt.h:468 [inline] raw_spin_unlock_irqrestore_wake include/linux/sched/wake_q.h:93 [inline] rtlock_slowlock kernel/locking/rtmutex.c:1896 [inline] rtlock_lock kernel/locking/spinlock_rt.c:43 [inline] __rt_spin_lock kernel/locking/spinlock_rt.c:49 [inline] rt_spin_lock+0x162/0x3e0 kernel/locking/spinlock_rt.c:57 spin_lock include/linux/spinlock_rt.h:44 [inline] ___slab_alloc+0x12f/0x1400 mm/slub.c:4516 __slab_alloc+0xc6/0x1f0 mm/slub.c:4774 __slab_alloc_node mm/slub.c:4850 [inline] slab_alloc_node mm/slub.c:5246 [inline] kmem_cache_alloc_noprof+0x101/0x6c0 mm/slub.c:5265 skb_ext_maybe_cow net/core/skbuff.c:7041 [inline] skb_ext_add+0x1b6/0x8f0 net/core/skbuff.c:7116 nf_bridge_unshare net/bridge/br_netfilter_hooks.c:169 [inline] br_nf_forward_ip+0xc6/0x7e0 net/bridge/br_netfilter_hooks.c:681 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0xc5/0x220 net/netfilter/core.c:623 nf_hook include/linux/netfilter.h:273 [inline] NF_HOOK+0x215/0x3c0 include/linux/netfilter.h:316 __br_forward+0x41e/0x600 net/bridge/br_forward.c:115 deliver_clone net/bridge/br_forward.c:131 [inline] maybe_deliver+0xb5/0x160 net/bridge/br_forward.c:191 br_flood+0x31a/0x6a0 net/bridge/br_forward.c:238 br_handle_frame_finish+0x15a3/0x1c90 net/bridge/br_input.c:229 br_nf_hook_thresh+0x3c6/0x4a0 net/bridge/br_netfilter_hooks.c:-1 br_nf_pre_routing_finish_ipv6+0x999/0xd60 net/bridge/br_netfilter_ipv6.c:-1 NF_HOOK include/linux/netfilter.h:318 [inline] br_nf_pre_routing_ipv6+0x37e/0x6b0 net/bridge/br_netfilter_ipv6.c:184 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_bridge_pre net/bridge/br_input.c:291 [inline] br_handle_frame+0x971/0x1500 net/bridge/br_input.c:442 __netif_receive_skb_core+0x95f/0x2f90 net/core/dev.c:6024 __netif_receive_skb_one_core net/core/dev.c:6135 [inline] __netif_receive_skb+0x72/0x380 net/core/dev.c:6250 process_backlog+0x315/0x8f0 net/core/dev.c:6602 __napi_poll+0xae/0x520 net/core/dev.c:7666 napi_poll net/core/dev.c:7729 [inline] net_rx_action+0x672/0xe00 net/core/dev.c:7881 handle_softirqs+0x226/0x6d0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0xcf/0x190 kernel/softirq.c:1138 smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246