syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 ticks this GP) idle=30e4/1/0x4000000000000000 softirq=71244/71244 fqs=132
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P10969/1:b..l
rcu: 	(detected by 1, t=10506 jiffies, g=48949, q=1100 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 13284 Comm: syz.4.1691 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:__lock_acquire+0x853/0x2cf0 kernel/locking/lockdep.c:-1
Code: 48 89 d8 48 c1 e8 20 29 c5 89 c1 c1 c1 04 31 e9 01 d8 29 cb 89 ca c1 c2 06 31 da 01 c1 29 d0 89 d6 c1 c6 08 31 c6 01 ca 29 f1 <89> f3 c1 c3 10 31 cb 01 d6 29 da 89 dd c1 c5 13 31 d5 01 f3 29 ee
RSP: 0018:ffffc90000007b18 EFLAGS: 00000012
RAX: 00000000000367e8 RBX: 0000000000000da9 RCX: 000000000364813d
RDX: 00000000fffc8a6a RSI: 00000000fc9b7117 RDI: ffff8880343d3d80
RBP: 0000000000000da9 R08: ffffffff89b86c54 R09: ffff88801b7902c0
R10: dffffc0000000000 R11: ffffffff89b86ba0 R12: ffff8880343d4938
R13: ffff8880343d4938 R14: ffff8880343d3d80 R15: 0000000000000001
FS:  00007ff29d7f66c0(0000) GS:ffff88812528d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f71fa613000 CR3: 0000000078c3c000 CR4: 0000000000350ef0
Call Trace:
 <IRQ>
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
 __raw_spin_lock include/linux/spinlock_api_smp.h:158 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:158
 spin_lock include/linux/spinlock.h:342 [inline]
 advance_sched+0xb4/0xc20 net/sched/sch_taprio.c:930
 __run_hrtimer kernel/time/hrtimer.c:1930 [inline]
 __hrtimer_run_queues+0x3c0/0xa20 kernel/time/hrtimer.c:1994
 hrtimer_interrupt+0x44b/0x950 kernel/time/hrtimer.c:2113
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1067
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1061
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_acquire+0x221/0x350 kernel/locking/lockdep.c:5872
Code: ff ff ff e8 e1 11 07 0a f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 cb 7c 97 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 9b 8d 6e ff cc 48 8d 3d 58 61 92
RSP: 0018:ffffc90004d7f9a8 EFLAGS: 00000282
RAX: d62927ef10c5a800 RBX: 0000000000000000 RCX: 0000000000000046
RDX: 000000005f55cb00 RSI: ffffffff8e219b45 RDI: ffffffff8c28af60
RBP: ffffffff8218804f R08: ffffffff8218804f R09: ffff88802c857178
R10: dffffc0000000000 R11: fffff520009aff5b R12: 0000000000000001
R13: ffff88802c857178 R14: 0000000000000001 R15: 0000000000000246
 __might_fault+0xcb/0x130 mm/memory.c:7324
 _inline_copy_from_user include/linux/uaccess.h:169 [inline]
 _copy_from_user+0x28/0xb0 lib/usercopy.c:18
 copy_from_user include/linux/uaccess.h:223 [inline]
 copy_msghdr_from_user net/socket.c:2628 [inline]
 recvmsg_copy_msghdr net/socket.c:2884 [inline]
 ___sys_recvmsg+0x175/0x590 net/socket.c:2956
 do_recvmmsg+0x334/0x800 net/socket.c:3055
 __sys_recvmmsg net/socket.c:3129 [inline]
 __do_sys_recvmmsg net/socket.c:3152 [inline]
 __se_sys_recvmmsg net/socket.c:3145 [inline]
 __x64_sys_recvmmsg+0x198/0x250 net/socket.c:3145
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff29f59cdd9
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:00007ff29d7f6028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007ff29f816090 RCX: 00007ff29f59cdd9
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000004
RBP: 00007ff29f632d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff29f816128 R14: 00007ff29f816090 R15: 00007ffeb0e3c6c8
 </TASK>
task:kworker/u8:15   state:R  running task     stack:23656 pid:10969 tgid:10969 ppid:2      task_flags:0x4288060 flags:0x00080000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1821/0x5740 kernel/sched/core.c:7189
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7513
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline]
 irqentry_exit+0x14f/0x760 kernel/entry/common.c:164
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:find_inode_fast+0x181/0x550 fs/inode.c:1096
Code: 01 48 c7 c7 80 73 de 8b be 48 03 00 00 48 c7 c2 c0 73 de 8b e8 f0 19 57 ff 4c 89 e8 48 c1 e8 03 48 89 44 24 28 42 80 3c 38 00 <74> 08 4c 89 ef e8 b5 1d e6 ff 49 8b 6d 00 48 85 ed 0f 94 c0 48 81
RSP: 0018:ffffc9000462f300 EFLAGS: 00000246
RAX: 1ffff920001b0dc6 RBX: 0000000000000000 RCX: ffff8880271a9ec0
RDX: 0000000000000000 RSI: ffffffff8c28af40 RDI: ffffffff8c28af00
RBP: 0000000000000001 R08: ffffffff824ae102 R09: ffffffff8e95cd60
R10: dffffc0000000000 R11: ffffed10037d0a37 R12: ffff88803382c000
R13: ffffc90000d86e30 R14: 0000000000042edc R15: dffffc0000000000
 ilookup+0xbd/0x1c0 fs/inode.c:1683
 kernfs_clear_inode_nlink fs/kernfs/dir.c:1529 [inline]
 __kernfs_remove+0x5de/0x8e0 fs/kernfs/dir.c:1592
 kernfs_remove_by_name_ns+0xc0/0x140 fs/kernfs/dir.c:1798
 kernfs_remove_by_name include/linux/kernfs.h:639 [inline]
 remove_files fs/sysfs/group.c:28 [inline]
 sysfs_remove_group+0xfc/0x2e0 fs/sysfs/group.c:328
 sysfs_remove_groups+0x54/0xb0 fs/sysfs/group.c:352
 device_remove_groups drivers/base/core.c:2844 [inline]
 device_remove_attrs+0x1cb/0x280 drivers/base/core.c:2974
 device_del+0x51f/0x8f0 drivers/base/core.c:3894
 unregister_netdevice_many_notify+0x1d5f/0x22c0 net/core/dev.c:12453
 unregister_netdevice_many net/core/dev.c:12481 [inline]
 default_device_exit_batch+0x962/0x9e0 net/core/dev.c:13073
 ops_exit_list net/core/net_namespace.c:205 [inline]
 ops_undo_list+0x52b/0x940 net/core/net_namespace.c:252
 cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
 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>
rcu: rcu_preempt kthread starved for 9845 jiffies! g48949 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:27536 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1821/0x5740 kernel/sched/core.c:7189
 __schedule_loop kernel/sched/core.c:7268 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7283
 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095
 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297
 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>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 5608 Comm: syz-executor Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:get_current arch/x86/include/asm/current.h:25 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x70 kernel/kcov.c:216
Code: 8b 3d 44 9e 60 0c 48 89 de 5b e9 e3 ec 5f 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0d 28 6e 73 11 65 8b 15 49 6e 73 11 81 e2 00 01 ff 00 74
RSP: 0018:ffffc9000360f558 EFLAGS: 00000202
RAX: ffffffff81b9be66 RBX: ffff8880b873c148 RCX: ffff8880334c9ec0
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000360f6a0 R08: ffffffff9030b6f7 R09: 1ffffffff20616de
R10: dffffc0000000000 R11: fffffbfff20616df R12: 1ffff110170c8589
R13: dffffc0000000000 R14: ffff8880b8642c48 R15: 0000000000000000
FS:  0000555560057540(0000) GS:ffff88812538d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fec91e6fff8 CR3: 000000007564f000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 csd_lock_wait kernel/smp.c:342 [inline]
 smp_call_function_many_cond+0xfe6/0x13d0 kernel/smp.c:892
 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1057
 __flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline]
 flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
 flush_tlb_mm_range+0x5c3/0x10b0 arch/x86/mm/tlb.c:1451
 tlb_flush arch/x86/include/asm/tlb.h:23 [inline]
 tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:509 [inline]
 tlb_flush_mmu+0x1af/0xa30 mm/mmu_gather.c:423
 tlb_finish_mmu+0xf9/0x230 mm/mmu_gather.c:549
 unmap_region+0x2a5/0x330 mm/vma.c:491
 vms_clear_ptes mm/vma.c:1303 [inline]
 vms_complete_munmap_vmas+0x493/0xc60 mm/vma.c:1345
 do_vmi_align_munmap+0x3b7/0x4b0 mm/vma.c:1604
 do_vmi_munmap+0x252/0x2d0 mm/vma.c:1652
 __vm_munmap+0x22c/0x3d0 mm/vma.c:3285
 __do_sys_munmap mm/mmap.c:1079 [inline]
 __se_sys_munmap mm/mmap.c:1076 [inline]
 __x64_sys_munmap+0x60/0x70 mm/mmap.c:1076
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fec90f9cc07
Code: 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 0b 00 00 00 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:00007ffdc7a869b8 EFLAGS: 00000202 ORIG_RAX: 000000000000000b
RAX: ffffffffffffffda RBX: 0000000000009000 RCX: 00007fec90f9cc07
RDX: 00007fec90f9a570 RSI: 0000000000009000 RDI: 00007fec91e67000
RBP: 00007fec91e67000 R08: 00000000000033e6 R09: 0000000000000000
R10: 0000000000000008 R11: 0000000000000202 R12: 00007ffdc7a86a60
R13: 0000000000000000 R14: 0000000000002201 R15: 0000000000000000
 </TASK>