rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P7834/1:b..l P7845/1:b..l rcu: (detected by 0, t=10503 jiffies, g=24273, q=1179 ncpus=2) task:syz.3.354 state:R running task stack:27320 pid:7845 tgid:7840 ppid:5836 task_flags:0x40054c flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5396 [inline] __schedule+0x116a/0x5de0 kernel/sched/core.c:6785 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7108 irqentry_exit+0x36/0x90 kernel/entry/common.c:307 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:unwind_next_frame+0x604/0x20a0 arch/x86/kernel/unwind_orc.c:517 Code: 41 80 fe 04 0f 84 17 0a 00 00 41 80 fe 05 0f 85 cf 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 14 24 48 c1 ea 03 80 3c 02 00 <0f> 85 0f 16 00 00 48 89 c8 4d 8b 7d 38 48 ba 00 00 00 00 00 fc ff RSP: 0018:ffffc9000bd072c8 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: 0000000000000001 RCX: ffffffff9141913a RDX: 1ffff920017a0e6e RSI: 0000000000000001 RDI: ffffffff90bc8620 RBP: ffffc9000bd07380 R08: ffffffff9141913e R09: 0000000000000000 R10: 0000000000000000 R11: 000000000000a50a R12: ffffc9000bd07388 R13: ffffc9000bd07338 R14: 0000000000000005 R15: 0000000000000000 arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 unpoison_slab_object mm/kasan/common.c:319 [inline] __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:345 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4148 [inline] slab_alloc_node mm/slub.c:4197 [inline] kmem_cache_alloc_noprof+0x1cb/0x3b0 mm/slub.c:4204 kmem_alloc_batch+0x49/0x170 lib/debugobjects.c:371 fill_pool lib/debugobjects.c:403 [inline] debug_objects_fill_pool lib/debugobjects.c:725 [inline] debug_objects_fill_pool+0x228/0x500 lib/debugobjects.c:697 debug_object_activate+0x10b/0x4c0 lib/debugobjects.c:814 debug_rcu_head_queue kernel/rcu/rcu.h:236 [inline] __call_rcu_common.constprop.0+0x35/0xa10 kernel/rcu/tree.c:3079 slab_free_hook mm/slub.c:2345 [inline] slab_free mm/slub.c:4643 [inline] kmem_cache_free+0x16d/0x4d0 mm/slub.c:4745 exit_mmap+0x511/0xb90 mm/mmap.c:1309 __mmput+0x12a/0x410 kernel/fork.c:1121 mmput+0x62/0x70 kernel/fork.c:1144 exit_mm kernel/exit.c:581 [inline] do_exit+0x7c4/0x2bd0 kernel/exit.c:952 do_group_exit+0xd3/0x2a0 kernel/exit.c:1105 get_signal+0x2673/0x26d0 kernel/signal.c:3034 arch_do_signal_or_restart+0x8f/0x790 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop+0x84/0x110 kernel/entry/common.c:111 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline] do_syscall_64+0x3f6/0x490 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f8dc318e929 RSP: 002b:00007f8dc3f85038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: 0000000000000022 RBX: 00007f8dc33b6240 RCX: 00007f8dc318e929 RDX: 0000000000000000 RSI: 0000200000000400 RDI: ffffffffffffff9c RBP: 00007f8dc3210b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f8dc33b6240 R15: 00007ffe55293eb8 task:syz.2.358 state:R running task stack:26280 pid:7834 tgid:7834 ppid:5829 task_flags:0x400040 flags:0x00004006 Call Trace: context_switch kernel/sched/core.c:5396 [inline] __schedule+0x116a/0x5de0 kernel/sched/core.c:6785 preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:6965 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] insert_page+0x139/0x200 mm/memory.c:2214 vm_insert_page+0x2c1/0x440 mm/memory.c:2363 kcov_mmap+0xbf/0x140 kernel/kcov.c:506 call_mmap include/linux/fs.h:2286 [inline] mmap_file mm/internal.h:167 [inline] __mmap_new_file_vma mm/vma.c:2405 [inline] __mmap_new_vma mm/vma.c:2467 [inline] __mmap_region+0x128b/0x25e0 mm/vma.c:2622 mmap_region+0x32b/0x3f0 mm/vma.c:2692 do_mmap+0xa3e/0x1210 mm/mmap.c:561 vm_mmap_pgoff+0x281/0x450 mm/util.c:579 ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:607 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline] __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline] __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3fa498e963 RSP: 002b:00007ffc8a04cc08 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007f3fa4bb62d8 RCX: 00007f3fa498e963 RDX: 0000000000000003 RSI: 0000000000400000 RDI: 00007f3fa2393000 RBP: 00007f3fa4bb6240 R08: 00000000000000db R09: 0000000000000000 R10: 0000000000000011 R11: 0000000000000246 R12: 00007f3fa4bb5fa0 R13: 00007f3fa4bb6240 R14: 00000000000010e4 R15: 0000000000000004 rcu: rcu_preempt kthread starved for 8282 jiffies! g24273 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:28744 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5396 [inline] __schedule+0x116a/0x5de0 kernel/sched/core.c:6785 __schedule_loop kernel/sched/core.c:6863 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6878 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2054 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2256 kthread+0x3c5/0x780 kernel/kthread.c:464 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148 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: 0 Comm: swapper/0 Not tainted 6.16.0-rc3-syzkaller-00233-g35e261cd95dd #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:unwind_next_frame+0xe70/0x20a0 arch/x86/kernel/unwind_orc.c:672 Code: b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 0f b6 04 02 84 c0 74 08 3c 03 0f 8e c6 0c 00 00 41 39 5d 00 0f 84 91 07 00 00 01 00 00 00 e9 5f f5 ff ff ba 28 00 00 00 4c 89 f6 4c 89 ef 48 RSP: 0018:ffffc90000006ae8 EFLAGS: 00000283 RAX: ffffffff8e208001 RBX: ffffffff8e207f58 RCX: ffffffff8e208001 RDX: ffffffff8e207f60 RSI: ffffffff8e207f48 RDI: ffffc90000006b68 RBP: ffffffff8e200000 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: ffffc90000006ba8 R13: ffffc90000006b58 R14: ffffffff8e207f58 R15: ffffc90000006b8c FS: 0000000000000000(0000) GS:ffff88812475d000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000006a0000 CR3: 000000007c9d0000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x51/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2381 [inline] slab_free mm/slub.c:4643 [inline] kmem_cache_free+0x2d1/0x4d0 mm/slub.c:4745 kfree_skbmem+0x1a4/0x1f0 net/core/skbuff.c:1110 __kfree_skb net/core/skbuff.c:1167 [inline] sk_skb_reason_drop+0x136/0x1a0 net/core/skbuff.c:1204 kfree_skb_reason include/linux/skbuff.h:1275 [inline] kfree_skb include/linux/skbuff.h:1284 [inline] ip6_mc_input+0x780/0xfd0 net/ipv6/ip6_input.c:591 dst_input include/net/dst.h:469 [inline] dst_input include/net/dst.h:467 [inline] ip6_rcv_finish+0x3a5/0x5b0 net/ipv6/ip6_input.c:79 ip_sabotage_in+0x21e/0x290 net/bridge/br_netfilter_hooks.c:993 nf_hook_entry_hookfn include/linux/netfilter.h:157 [inline] nf_hook_slow+0xbb/0x200 net/netfilter/core.c:623 nf_hook.constprop.0+0x422/0x750 include/linux/netfilter.h:272 NF_HOOK include/linux/netfilter.h:315 [inline] ipv6_rcv+0xa4/0x680 net/ipv6/ip6_input.c:309 __netif_receive_skb_one_core+0x12d/0x1e0 net/core/dev.c:5977 __netif_receive_skb+0x1d/0x160 net/core/dev.c:6090 netif_receive_skb_internal net/core/dev.c:6176 [inline] netif_receive_skb+0x137/0x7b0 net/core/dev.c:6235 NF_HOOK include/linux/netfilter.h:317 [inline] NF_HOOK include/linux/netfilter.h:311 [inline] br_pass_frame_up+0x346/0x490 net/bridge/br_input.c:70 br_handle_frame_finish+0xf5a/0x1ca0 net/bridge/br_input.c:227 br_nf_hook_thresh+0x307/0x410 net/bridge/br_netfilter_hooks.c:1170 br_nf_pre_routing_finish_ipv6+0x76a/0xfb0 net/bridge/br_netfilter_ipv6.c:154 NF_HOOK include/linux/netfilter.h:317 [inline] br_nf_pre_routing_ipv6+0x3cd/0x8c0 net/bridge/br_netfilter_ipv6.c:184 br_nf_pre_routing+0x860/0x15b0 net/bridge/br_netfilter_hooks.c:508 nf_hook_entry_hookfn include/linux/netfilter.h:157 [inline] nf_hook_bridge_pre net/bridge/br_input.c:283 [inline] br_handle_frame+0xad5/0x14b0 net/bridge/br_input.c:434 __netif_receive_skb_core.constprop.0+0xa26/0x4a00 net/core/dev.c:5863 __netif_receive_skb_one_core+0xb0/0x1e0 net/core/dev.c:5975 __netif_receive_skb+0x1d/0x160 net/core/dev.c:6090 process_backlog+0x442/0x15e0 net/core/dev.c:6442 __napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7414 napi_poll net/core/dev.c:7478 [inline] net_rx_action+0xa9f/0xfe0 net/core/dev.c:7605 handle_softirqs+0x216/0x8e0 kernel/softirq.c:579 __do_softirq kernel/softirq.c:613 [inline] invoke_softirq kernel/softirq.c:453 [inline] __irq_exit_rcu+0x109/0x170 kernel/softirq.c:680 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82 Code: fb 74 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d f3 fe 2c 00 fb f4 0c fb 02 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0018:ffffffff8e207e08 EFLAGS: 000002c2 RAX: 0000000000f1bfa5 RBX: 0000000000000000 RCX: ffffffff8b7d0c29 RDX: 0000000000000000 RSI: ffffffff8de13e33 RDI: ffffffff8c1568e0 RBP: fffffbfff1c52ef0 R08: 0000000000000001 R09: ffffed1017086645 R10: ffff8880b843322b R11: 0000000000000001 R12: 0000000000000000 R13: ffffffff8e297780 R14: ffffffff90a83050 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:749 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:117 cpuidle_idle_call kernel/sched/idle.c:185 [inline] do_idle+0x391/0x510 kernel/sched/idle.c:325 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:423 rest_init+0x16b/0x2b0 init/main.c:745 start_kernel+0x3ee/0x4d0 init/main.c:1102 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:307 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:288 common_startup_64+0x13e/0x148