syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5829/1:b..l P5817/1:b..l P25689/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=125145, q=181 ncpus=1)
task:syz.0.9202      state:R  running task     stack:28752 pid:25689 tgid:25689 ppid:5829   task_flags:0x40044c flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5260 [inline]
 __schedule+0xfe4/0x5e10 kernel/sched/core.c:6867
 preempt_schedule_common+0x42/0xc0 kernel/sched/core.c:7051
 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]
 zap_pte_range mm/memory.c:1888 [inline]
 zap_pmd_range mm/memory.c:1950 [inline]
 zap_pud_range mm/memory.c:1978 [inline]
 zap_p4d_range mm/memory.c:1999 [inline]
 unmap_page_range+0x14ee/0x43e0 mm/memory.c:2020
 unmap_single_vma+0x153/0x240 mm/memory.c:2062
 unmap_vmas+0x218/0x470 mm/memory.c:2104
 exit_mmap+0x181/0xae0 mm/mmap.c:1277
 __mmput+0x12a/0x410 kernel/fork.c:1173
 mmput+0x67/0x80 kernel/fork.c:1196
 exit_mm kernel/exit.c:581 [inline]
 do_exit+0x78a/0x2a30 kernel/exit.c:959
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1112
 get_signal+0x1ec7/0x21e0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x91/0x770 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
 exit_to_user_mode_loop+0x86/0x4b0 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x4ea/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa65735b58e
RSP: 002b:00007fa65819cf58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 00007fa65819d6c0 RCX: 00007fa65735b58e
RDX: 00007fa65819cfb0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fa657408bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa657616038 R14: 00007fa657615fa0 R15: 00007ffff078c6d8
 </TASK>
task:syz-executor    state:R  running task     stack:22840 pid:5817  tgid:5817  ppid:5816   task_flags:0x400100 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5260 [inline]
 __schedule+0xfe4/0x5e10 kernel/sched/core.c:6867
 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7194
 irqentry_exit+0x17b/0x670 kernel/entry/common.c:216
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:debug_lockdep_rcu_enabled+0x2b/0x40 kernel/rcu/update.c:320
Code: 0f 1e fa 8b 05 06 85 43 05 85 c0 74 20 8b 05 90 b4 43 05 85 c0 74 16 65 48 8b 05 48 d8 6f 08 8b 80 2c 0b 00 00 85 c0 0f 94 c0 <0f> b6 c0 e9 3d 28 03 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 90
RSP: 0018:ffffc90003fefb48 EFLAGS: 00000246
RAX: 0000000000000001 RBX: 0000000000090d32 RCX: 1ffff11027fff4ca
RDX: dffffc0000000000 RSI: ffffffff827c255a RDI: ffff88813fffa650
RBP: ffff88801d300000 R08: 0000000000000006 R09: 0000000000001000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffffea0002434c80
 rcu_read_lock_held_common kernel/rcu/update.c:105 [inline]
 rcu_read_lock_held+0x9/0x50 kernel/rcu/update.c:349
 lookup_page_ext+0x6e/0x100 mm/page_ext.c:254
 page_ext_iter_begin include/linux/page_ext.h:132 [inline]
 __page_table_check_zero+0xe1/0x410 mm/page_table_check.c:139
 page_table_check_free include/linux/page_table_check.h:43 [inline]
 free_pages_prepare mm/page_alloc.c:1434 [inline]
 __free_frozen_pages+0x802/0x1130 mm/page_alloc.c:2973
 discard_slab mm/slub.c:3346 [inline]
 __put_partials+0x127/0x160 mm/slub.c:3886
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xe0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 __do_kmalloc_node mm/slub.c:5656 [inline]
 __kmalloc_noprof+0x300/0x9c0 mm/slub.c:5669
 kmalloc_noprof include/linux/slab.h:961 [inline]
 kmalloc_array_noprof include/linux/slab.h:1003 [inline]
 alloc_pipe_info+0x1ec/0x590 fs/pipe.c:817
 get_pipe_inode fs/pipe.c:896 [inline]
 create_pipe_files+0x8c/0x970 fs/pipe.c:928
 __do_pipe_flags fs/pipe.c:990 [inline]
 do_pipe2+0xbd/0x1e0 fs/pipe.c:1038
 __do_sys_pipe2 fs/pipe.c:1056 [inline]
 __se_sys_pipe2 fs/pipe.c:1054 [inline]
 __x64_sys_pipe2+0x54/0x80 fs/pipe.c:1054
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f974d799ce9
RSP: 002b:00007fff0005d288 EFLAGS: 00000246 ORIG_RAX: 0000000000000125
RAX: ffffffffffffffda RBX: 000055556cc02ef0 RCX: 00007f974d799ce9
RDX: 0000000000000004 RSI: 0000000000000000 RDI: 00007fff0005d298
RBP: 00007fff0005d860 R08: 00007f974d9e4cc0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff0005d6a0
R13: 000055556cc03508 R14: 000055556cc06830 R15: 00007fff0005d3e0
 </TASK>
task:syz-executor    state:R  running task     stack:19224 pid:5829  tgid:5829  ppid:1      task_flags:0x40054c flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5260 [inline]
 __schedule+0xfe4/0x5e10 kernel/sched/core.c:6867
 preempt_schedule_common+0x42/0xc0 kernel/sched/core.c:7051
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __raw_read_unlock include/linux/rwlock_api_smp.h:233 [inline]
 _raw_read_unlock+0x3e/0x50 kernel/locking/spinlock.c:260
 zap_pid_ns_processes+0x259/0x6a0 kernel/pid_namespace.c:233
 find_child_reaper kernel/exit.c:622 [inline]
 forget_original_parent kernel/exit.c:706 [inline]
 exit_notify kernel/exit.c:743 [inline]
 do_exit+0x22da/0x2a30 kernel/exit.c:983
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1112
 get_signal+0x1ec7/0x21e0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x91/0x770 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
 exit_to_user_mode_loop+0x86/0x4b0 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x4ea/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa65735b58e
RSP: 002b:00007ffff078c9b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
RAX: 0000000000000000 RBX: 000055557b302500 RCX: 00007fa65735b58e
RDX: 00007ffff078ca10 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffff078ca7c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000008f1
R13: 0000000000000064 R14: 0000000000095ec3 R15: 00007ffff078cad0
 </TASK>
rcu: rcu_preempt kthread starved for 5472 jiffies! g125145 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:28408 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5260 [inline]
 __schedule+0xfe4/0x5e10 kernel/sched/core.c:6867
 __schedule_loop kernel/sched/core.c:6949 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:6964
 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1a9/0xb00 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x21e/0x320 kernel/rcu/tree.c:2285
 kthread+0x3b3/0x730 kernel/kthread.c:463
 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 3411 Comm: kworker/R-bat_e Tainted: G     U    I  L      syzkaller #0 PREEMPT(full) 
Tainted: [U]=USER, [I]=FIRMWARE_WORKAROUND, [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026
Workqueue: bat_events batadv_dat_purge
RIP: 0010:unwind_next_frame+0x11de/0x1ea0 arch/x86/kernel/unwind_orc.c:532
Code: ff ff 80 3d 96 92 e9 0e 00 0f 85 85 f1 ff ff e9 f0 bb 6a ff 48 b8 00 00 00 00 00 fc ff df 48 8b 14 24 48 c1 ea 03 80 3c 02 00 <0f> 85 02 09 00 00 48 89 c8 4d 8b 7d 38 48 ba 00 00 00 00 00 fc ff
RSP: 0018:ffffc90000006ed8 EFLAGS: 00000246
RAX: dffffc0000000000 RBX: 0000000000000002 RCX: ffffffff91634dfa
RDX: 1ffff92000000df0 RSI: 0000000000000001 RDI: ffffffff90d8f9d4
RBP: ffffc90000006f90 R08: ffffffff91634dfe R09: 0000000000000007
R10: 0000000000000200 R11: 0000000000016f75 R12: ffffc90000006f98
R13: ffffc90000006f48 R14: 0000000000000005 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881245e5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa65819d9a0 CR3: 0000000075e88000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 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
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 kmem_cache_alloc_noprof+0x2ad/0x780 mm/slub.c:5270
 skb_clone+0x190/0x400 net/core/skbuff.c:2087
 deliver_clone net/bridge/br_forward.c:125 [inline]
 maybe_deliver+0xd4/0x180 net/bridge/br_forward.c:191
 br_flood+0x193/0x650 net/bridge/br_forward.c:238
 br_handle_frame_finish+0xf57/0x1f00 net/bridge/br_input.c:229
 br_nf_hook_thresh+0x30d/0x420 net/bridge/br_netfilter_hooks.c:1167
 br_nf_pre_routing_finish_ipv6+0x769/0xfb0 net/bridge/br_netfilter_ipv6.c:154
 NF_HOOK include/linux/netfilter.h:318 [inline]
 br_nf_pre_routing_ipv6+0x39c/0x8b0 net/bridge/br_netfilter_ipv6.c:184
 br_nf_pre_routing+0x93b/0x1510 net/bridge/br_netfilter_hooks.c:508
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:291 [inline]
 br_handle_frame+0xa68/0x1510 net/bridge/br_input.c:442
 __netif_receive_skb_core.constprop.0+0x6d7/0x3460 net/core/dev.c:6039
 __netif_receive_skb_one_core+0xb0/0x1e0 net/core/dev.c:6150
 __netif_receive_skb+0x1f/0x120 net/core/dev.c:6265
 process_backlog+0x37a/0x1580 net/core/dev.c:6617
 __napi_poll.constprop.0+0xaf/0x450 net/core/dev.c:7681
 napi_poll net/core/dev.c:7744 [inline]
 net_rx_action+0xa40/0xf20 net/core/dev.c:7896
 handle_softirqs+0x1ea/0x910 kernel/softirq.c:622
 do_softirq kernel/softirq.c:523 [inline]
 do_softirq+0xac/0xe0 kernel/softirq.c:510
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0xf8/0x120 kernel/softirq.c:450
 spin_unlock_bh include/linux/spinlock.h:396 [inline]
 __batadv_dat_purge.part.0+0x294/0x3c0 net/batman-adv/distributed-arp-table.c:185
 __batadv_dat_purge net/batman-adv/distributed-arp-table.c:166 [inline]
 batadv_dat_purge+0x4b/0xa0 net/batman-adv/distributed-arp-table.c:204
 process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 rescuer_thread+0x8f1/0xf40 kernel/workqueue.c:3528
 kthread+0x3b3/0x730 kernel/kthread.c:463
 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>