rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P12607/1:b..l P12579/1:b..l P1026/1:b..l rcu: (detected by 1, t=10502 jiffies, g=63313, q=870 ncpus=2) task:kworker/u8:8 state:R running task stack:24056 pid:1026 tgid:1026 ppid:2 task_flags:0x4288060 flags:0x00080000 Workqueue: netns cleanup_net Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x1295/0x67a0 kernel/sched/core.c:7189 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7513 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:468 [inline] irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x205/0x970 kernel/entry/common.c:164 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_acquire+0x5e/0x370 kernel/locking/lockdep.c:5872 Code: 05 7b 24 25 12 83 f8 07 0f 87 d9 02 00 00 48 0f a3 05 86 89 f2 0e 0f 82 a4 02 00 00 8b 35 0e bd f2 0e 85 f6 0f 85 bf 00 00 00 <48> 8b 44 24 30 65 48 2b 05 1d 24 25 12 0f 85 ed 02 00 00 48 83 c4 RSP: 0018:ffffc90004c4f230 EFLAGS: 00000206 RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000006 RDX: 0000000000000000 RSI: ffffffff8dee9983 RDI: ffffffff8c1c4480 RBP: ffffffff8e7e5620 R08: 00000000202ff075 R09: 0000000000000007 R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:838 [inline] class_rcu_constructor include/linux/rcupdate.h:1181 [inline] unwind_next_frame+0xd1/0x2090 arch/x86/kernel/unwind_orc.c:495 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:556 __call_rcu_common.constprop.0+0xa5/0x9b0 kernel/rcu/tree.c:3131 kernfs_put.part.0+0x22f/0x720 fs/kernfs/dir.c:618 kernfs_put fs/kernfs/dir.c:1788 [inline] kernfs_remove_by_name_ns+0xf3/0x120 fs/kernfs/dir.c:1799 kernfs_remove_by_name include/linux/kernfs.h:639 [inline] remove_files+0x96/0x1c0 fs/sysfs/group.c:28 sysfs_remove_group+0x8b/0x1b0 fs/sysfs/group.c:328 sysfs_remove_groups fs/sysfs/group.c:352 [inline] sysfs_remove_groups+0x60/0xb0 fs/sysfs/group.c:344 device_remove_groups drivers/base/core.c:2844 [inline] device_remove_attrs+0x192/0x290 drivers/base/core.c:2974 device_del+0x36e/0x9b0 drivers/base/core.c:3894 unregister_netdevice_many_notify+0x179e/0x24f0 net/core/dev.c:12456 ops_exit_rtnl_list net/core/net_namespace.c:187 [inline] ops_undo_list+0x8ff/0xab0 net/core/net_namespace.c:248 cleanup_net+0x499/0x920 net/core/net_namespace.c:702 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3314 process_scheduled_works kernel/workqueue.c:3397 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3478 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 task:syz.0.1507 state:R running task stack:27240 pid:12579 tgid:12576 ppid:5615 task_flags:0x40054c flags:0x00080001 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x1295/0x67a0 kernel/sched/core.c:7189 preempt_schedule_common+0x42/0xc0 kernel/sched/core.c:7370 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:169 [inline] _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:190 spin_unlock include/linux/spinlock.h:390 [inline] zap_pte_range mm/memory.c:1964 [inline] zap_pmd_range mm/memory.c:2020 [inline] zap_pud_range mm/memory.c:2048 [inline] zap_p4d_range mm/memory.c:2069 [inline] __zap_vma_range+0x24b4/0x4a30 mm/memory.c:2109 unmap_vmas+0x299/0x5f0 mm/memory.c:2178 exit_mmap+0x1ef/0xa10 mm/mmap.c:1300 __mmput+0x12a/0x410 kernel/fork.c:1178 mmput+0x67/0x80 kernel/fork.c:1201 exit_mm kernel/exit.c:582 [inline] do_exit+0x8b2/0x2af0 kernel/exit.c:964 do_group_exit+0xd5/0x2a0 kernel/exit.c:1119 get_signal+0x20ff/0x2210 kernel/signal.c:3037 arch_do_signal_or_restart+0x91/0x7e0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline] exit_to_user_mode_loop+0x98/0x670 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x666/0x870 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f555c39ce59 RSP: 002b:00007f555a5d5028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: 0000000000000010 RBX: 00007f555c616090 RCX: 00007f555c39ce59 RDX: 0000000000000000 RSI: 0000200000000140 RDI: 000000000000000a RBP: 00007f555c432d6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f555c616128 R14: 00007f555c616090 R15: 00007fff22808818 task:kworker/u8:20 state:R running task stack:28104 pid:12607 tgid:12607 ppid:6312 task_flags:0x8040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x1295/0x67a0 kernel/sched/core.c:7189 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7513 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:468 [inline] irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x205/0x970 kernel/entry/common.c:164 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_acquire+0x5e/0x370 kernel/locking/lockdep.c:5872 Code: 05 7b 24 25 12 83 f8 07 0f 87 d9 02 00 00 48 0f a3 05 86 89 f2 0e 0f 82 a4 02 00 00 8b 35 0e bd f2 0e 85 f6 0f 85 bf 00 00 00 <48> 8b 44 24 30 65 48 2b 05 1d 24 25 12 0f 85 ed 02 00 00 48 83 c4 RSP: 0018:ffffc9000582f688 EFLAGS: 00000206 RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffffffff8dee9983 RDI: ffffffff8c1c4480 RBP: ffffffff8e7e5620 R08: 00000000b5b85b68 R09: 0000000000000007 R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:838 [inline] class_rcu_constructor include/linux/rcupdate.h:1181 [inline] unwind_next_frame+0xd1/0x2090 arch/x86/kernel/unwind_orc.c:495 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2689 [inline] slab_free mm/slub.c:6251 [inline] kmem_cache_free+0x127/0x6c0 mm/slub.c:6378 free_filename fs/namei.c:147 [inline] putname+0xb1/0x110 fs/namei.c:306 class_filename_destructor include/linux/fs.h:2553 [inline] class_filename_kernel_destructor include/linux/fs.h:2554 [inline] open_exec+0x33/0x40 fs/exec.c:816 load_elf_binary+0x534/0x51b0 fs/binfmt_elf.c:907 search_binary_handler fs/exec.c:1664 [inline] exec_binprm fs/exec.c:1696 [inline] bprm_execve fs/exec.c:1748 [inline] bprm_execve+0x8f5/0x1740 fs/exec.c:1724 kernel_execve+0x31e/0x3a0 fs/exec.c:1892 call_usermodehelper_exec_async+0x239/0x4b0 kernel/umh.c:109 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: rcu_preempt kthread starved for 10597 jiffies! g63313 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:R running task stack:28216 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x1295/0x67a0 kernel/sched/core.c:7189 __schedule_loop kernel/sched/core.c:7268 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7283 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2297 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 12604 Comm: syz.4.1509 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:trace_lock_acquire include/trace/events/lock.h:24 [inline] RIP: 0010:lock_acquire+0x2f9/0x370 kernel/locking/lockdep.c:5831 Code: 8b fd ff ff 48 8d 74 24 08 b9 0a 00 00 00 ba 08 00 00 00 65 48 8b 3d ae 21 25 12 e8 11 c7 ff ff e9 6a fd ff ff e8 f7 64 08 00 <84> c0 0f 85 4f fd ff ff 48 8d 3d f8 f3 f5 0e 67 48 0f b9 3a e9 3e RSP: 0018:ffffc900057ff438 EFLAGS: 00000286 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000002 RDX: 0000000000000000 RSI: ffffffff8c1c4400 RDI: ffffffff8e1c1920 RBP: ffffffff8e7e5620 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000200 R11: 0000000000019b3f R12: 0000000000000002 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f3ad58e86c0(0000) GS:ffff888124386000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9ecc22ebfc CR3: 00000000755cb000 CR4: 00000000003526f0 Call Trace: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:838 [inline] class_rcu_constructor include/linux/rcupdate.h:1181 [inline] unwind_next_frame+0xd1/0x2090 arch/x86/kernel/unwind_orc.c:495 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2689 [inline] slab_free mm/slub.c:6251 [inline] kfree+0x223/0x6c0 mm/slub.c:6566 iter_file_splice_write+0x5fd/0x10a0 fs/splice.c:768 do_splice_from fs/splice.c:936 [inline] direct_splice_actor+0x192/0x6c0 fs/splice.c:1159 splice_direct_to_actor+0x345/0xa30 fs/splice.c:1103 do_splice_direct_actor fs/splice.c:1202 [inline] do_splice_direct+0x174/0x240 fs/splice.c:1228 do_sendfile+0xadc/0xe20 fs/read_write.c:1372 __do_sys_sendfile64 fs/read_write.c:1433 [inline] __se_sys_sendfile64 fs/read_write.c:1419 [inline] __x64_sys_sendfile64+0x1d8/0x220 fs/read_write.c:1419 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3ad499ce59 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f3ad58e8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007f3ad4c15fa0 RCX: 00007f3ad499ce59 RDX: 0000000000000000 RSI: 0000000000000007 RDI: 0000000000000008 RBP: 00007f3ad4a32d6f R08: 0000000000000000 R09: 0000000000000000 R10: 000000007fffffff R11: 0000000000000246 R12: 0000000000000000 R13: 00007f3ad4c16038 R14: 00007f3ad4c15fa0 R15: 00007fff837f6ba8