rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P9371/1:b..l P4978/1:b..l P5604/1:b..l P5870/1:b..l rcu: (detected by 0, t=10502 jiffies, g=42809, q=678404 ncpus=1) task:udevd state:R running task stack:24584 pid:5870 tgid:5870 ppid:4978 task_flags:0x40014c flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5533 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7284 preempt_schedule_common+0x7f/0xd0 kernel/sched/core.c:7463 preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:211 [inline] _raw_spin_unlock_irqrestore+0x76/0x80 kernel/locking/spinlock.c:221 spin_unlock_irqrestore include/linux/spinlock.h:425 [inline] lruvec_unlock_irqrestore include/linux/memcontrol.h:1535 [inline] folios_put_refs+0x8b0/0xb30 mm/folio.c:1028 free_pages_and_swap_cache+0x2ba/0x490 mm/swap_state.c:592 __tlb_batch_free_encoded_pages mm/mmu_gather.c:138 [inline] tlb_batch_pages_flush mm/mmu_gather.c:151 [inline] tlb_flush_mmu_free mm/mmu_gather.c:417 [inline] tlb_flush_mmu+0x6d3/0xa30 mm/mmu_gather.c:424 tlb_finish_mmu+0xf4/0x220 mm/mmu_gather.c:549 exit_mmap+0x4b2/0x9f0 mm/mmap.c:1328 __mmput+0x118/0x420 kernel/fork.c:1193 exit_mm+0x18e/0x240 kernel/exit.c:592 do_exit+0x6cd/0x2360 kernel/exit.c:974 do_group_exit+0x22d/0x2f0 kernel/exit.c:1129 __do_sys_exit_group kernel/exit.c:1140 [inline] __se_sys_exit_group kernel/exit.c:1138 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1138 x64_sys_call+0x18c6/0x18d0 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f81e48f16c5 RSP: 002b:00007ffd22575788 EFLAGS: 00000256 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000557cd7b2a650 RCX: 00007f81e48f16c5 RDX: 00000000000000e7 RSI: fffffffffffffe68 RDI: 0000000000000000 RBP: 0000557cd7b22910 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000256 R12: 0000000000000000 R13: 00007ffd225757d0 R14: 0000000000000000 R15: 0000000000000000 task:syz-executor state:R running task stack:23400 pid:5604 tgid:5604 ppid:5598 task_flags:0x40050c flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5533 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7284 preempt_schedule_common+0x7f/0xd0 kernel/sched/core.c:7463 preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:201 [inline] _raw_spin_unlock+0x41/0x50 kernel/locking/spinlock.c:213 spin_unlock include/linux/spinlock.h:401 [inline] zap_pte_range mm/memory.c:2095 [inline] zap_pmd_range mm/memory.c:2151 [inline] zap_pud_range mm/memory.c:2179 [inline] zap_p4d_range mm/memory.c:2200 [inline] __zap_vma_range+0x40e1/0x4f80 mm/memory.c:2240 unmap_vmas+0x390/0x550 mm/memory.c:2309 exit_mmap+0x293/0x9f0 mm/mmap.c:1315 __mmput+0x118/0x420 kernel/fork.c:1193 exit_mm+0x18e/0x240 kernel/exit.c:592 do_exit+0x6cd/0x2360 kernel/exit.c:974 do_group_exit+0x22d/0x2f0 kernel/exit.c:1129 get_signal+0x121b/0x12c0 kernel/signal.c:3112 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0x10e/0x770 kernel/entry/common.c:101 __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:343 [inline] do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff57b159357 RSP: 002b:00007ffca927c6e0 EFLAGS: 00000202 ORIG_RAX: 000000000000003d RAX: fffffffffffffe00 RBX: 00005555801a7500 RCX: 00007ff57b159357 RDX: 0000000040000000 RSI: 00007ffca927c73c RDI: ffffffffffffffff RBP: 00007ffca927c73c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008 R13: 0000000000000003 R14: 00007ffca927c998 R15: 0000000000000000 task:udevd state:R running task stack:22408 pid:4978 tgid:4978 ppid:1 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5533 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7284 preempt_schedule_irq+0x4b/0x90 kernel/sched/core.c:7606 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x14f/0x920 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:58 [inline] RIP: 0010:stack_access_ok arch/x86/kernel/unwind_orc.c:409 [inline] RIP: 0010:deref_stack_reg+0x9a/0x220 arch/x86/kernel/unwind_orc.c:419 Code: be 00 00 00 00 00 fc ff df 4d 8b 77 10 4c 89 fb 48 c1 eb 03 0f b6 04 33 84 c0 0f 85 39 01 00 00 41 83 3f 00 0f 95 c0 4c 39 c5 <0f> 96 c1 20 c1 4d 39 c6 0f 97 c0 20 c8 3c 01 75 18 49 8d 40 08 48 RSP: 0018:ffffc90004137898 EFLAGS: 00000297 RAX: 0000000000000001 RBX: 1ffff92000826f31 RCX: 0000000000000000 RDX: ffffc900041379c8 RSI: dffffc0000000000 RDI: ffffc90004137998 RBP: ffffc90004130000 R08: ffffc90004137dd8 R09: ffffc900041379d8 R10: dffffc0000000000 R11: fffff52000826f3d R12: 1ffff92000826f32 R13: 1ffff92000826f33 R14: ffffc90004138000 R15: ffffc90004137988 unwind_next_frame+0x19bd/0x2550 arch/x86/kernel/unwind_orc.c:-1 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 save_stack+0x122/0x230 mm/page_owner.c:183 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:338 reset_page_owner include/linux/page_owner.h:26 [inline] __free_pages_prepare mm/page_alloc.c:1418 [inline] __free_frozen_pages+0xc93/0xd90 mm/page_alloc.c:2962 __slab_free+0x274/0x2c0 mm/slub.c:5823 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:361 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4683 [inline] slab_alloc_node mm/slub.c:4996 [inline] kmem_cache_alloc_noprof+0x2b9/0x600 mm/slub.c:5010 alloc_filename fs/namei.c:147 [inline] do_getname+0x2e/0x250 fs/namei.c:187 getname_flags fs/namei.c:230 [inline] getname include/linux/fs.h:2557 [inline] class_filename_constructor include/linux/fs.h:2584 [inline] __do_sys_unlink fs/namei.c:5753 [inline] __se_sys_unlink+0x1e/0x140 fs/namei.c:5751 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f81e4915937 RSP: 002b:00007ffd22575938 EFLAGS: 00000202 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000bb8 RCX: 00007f81e4915937 RDX: 0000000000000000 RSI: 000000000e6ca080 RDI: 0000557cbee3d02e RBP: 0000000000000000 R08: 000000000e7629ba R09: 3fffffffffffffff R10: 4000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 0000557cbee58100 R14: 0000000000000000 R15: 0000000000000000 task:syz.1.1385 state:R running task stack:26888 pid:9371 tgid:9369 ppid:5610 task_flags:0x40044c flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5533 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7284 preempt_schedule_common+0x7f/0xd0 kernel/sched/core.c:7463 preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:201 [inline] _raw_spin_unlock+0x41/0x50 kernel/locking/spinlock.c:213 spin_unlock include/linux/spinlock.h:401 [inline] zap_pte_range mm/memory.c:2095 [inline] zap_pmd_range mm/memory.c:2151 [inline] zap_pud_range mm/memory.c:2179 [inline] zap_p4d_range mm/memory.c:2200 [inline] __zap_vma_range+0x40e1/0x4f80 mm/memory.c:2240 unmap_vmas+0x390/0x550 mm/memory.c:2309 exit_mmap+0x293/0x9f0 mm/mmap.c:1315 __mmput+0x118/0x420 kernel/fork.c:1193 exit_mm+0x18e/0x240 kernel/exit.c:592 do_exit+0x6cd/0x2360 kernel/exit.c:974 do_group_exit+0x22d/0x2f0 kernel/exit.c:1129 get_signal+0x121b/0x12c0 kernel/signal.c:3112 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0x10e/0x770 kernel/entry/common.c:101 __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:343 [inline] do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f65ca55ea0e RSP: 002b:00007f65cb465ed8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6 RAX: 0000000000000000 RBX: 00007f65cb4686c0 RCX: 00007f65ca55ea0e RDX: 00007f65cb465f30 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007f65cb466fd0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003 R13: 0000000800000000 R14: 0000000000000000 R15: 00007f65ca654272 rcu: rcu_preempt kthread starved for 7173 jiffies! g42809 f0x2 RCU_GP_WAIT_FQS(5) ->state=R ->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:27496 pid:17 tgid:17 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5533 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7284 __schedule_loop kernel/sched/core.c:7361 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7376 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2122 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2330 kthread+0x38b/0x480 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 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 3220 Comm: kworker/R-bat_e Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 Workqueue: bat_events batadv_tt_purge RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:58 [inline] RIP: 0010:unwind_next_frame+0x1a5e/0x2550 arch/x86/kernel/unwind_orc.c:694 Code: 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 48 89 df e8 c6 f8 bf 00 48 8b 03 4d 39 fc 0f 96 c1 4c 39 f8 0f 97 c2 20 ca 80 fa 01 <0f> 85 f4 00 00 00 49 8d 4f 08 4c 39 e1 0f 86 e7 00 00 00 48 39 c1 RSP: 0018:ffffc90000006e60 EFLAGS: 00000246 RAX: ffffc9000e838000 RBX: ffffc90000006f18 RCX: dffffc0000000001 RDX: ffffffff91130c01 RSI: 0000000000000000 RDI: ffffc90000006f10 RBP: 1ffffffff2226101 R08: ffffc9000e837a38 R09: ffffc90000006f58 R10: dffffc0000000000 R11: fffff52000000ded R12: ffffc9000e830000 R13: ffffffff817811df R14: ffffc90000006f08 R15: ffffc9000e837a38 FS: 0000000000000000(0000) GS:ffff888124cc6000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055555694e4e8 CR3: 0000000034dc1000 CR4: 0000000000350ef0 Call Trace: arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:351 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:377 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4683 [inline] slab_alloc_node mm/slub.c:4996 [inline] kmem_cache_alloc_node_noprof+0x354/0x610 mm/slub.c:5068 kmalloc_reserve net/core/skbuff.c:615 [inline] __alloc_skb+0x27a/0x7a0 net/core/skbuff.c:715 alloc_skb include/linux/skbuff.h:1384 [inline] __tcp_send_ack+0xaf/0x4f0 net/ipv4/tcp_output.c:4485 tcp_validate_incoming+0x1483/0x2440 net/ipv4/tcp_input.c:6386 tcp_rcv_established+0x8d6/0x2940 net/ipv4/tcp_input.c:6679 tcp_v6_do_rcv+0x8bd/0x1cc0 net/ipv6/tcp_ipv6.c:1628 tcp_v6_rcv+0x2496/0x2d90 net/ipv6/tcp_ipv6.c:1905 ip6_protocol_deliver_rcu+0xab9/0x1680 net/ipv6/ip6_input.c:479 ip6_input_finish+0x191/0x370 net/ipv6/ip6_input.c:534 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:325 ip6_input+0x16a/0x270 net/ipv6/ip6_input.c:545 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:325 __netif_receive_skb_one_core net/core/dev.c:6297 [inline] __netif_receive_skb net/core/dev.c:6410 [inline] process_backlog+0x795/0x18b0 net/core/dev.c:6761 __napi_poll+0xaa/0x330 net/core/dev.c:7830 napi_poll net/core/dev.c:7893 [inline] net_rx_action+0x61d/0xf50 net/core/dev.c:8050 handle_softirqs+0x226/0x860 kernel/softirq.c:645 do_softirq+0x77/0xd0 kernel/softirq.c:546 __local_bh_enable_ip+0x100/0x140 kernel/softirq.c:473 spin_unlock_bh include/linux/spinlock.h:407 [inline] batadv_tt_global_purge net/batman-adv/translation-table.c:2390 [inline] batadv_tt_purge+0x4ae/0xa10 net/batman-adv/translation-table.c:3754 process_one_work kernel/workqueue.c:3396 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479 rescuer_thread+0x7c5/0x10e0 kernel/workqueue.c:3703 kthread+0x38b/0x480 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