syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P22523/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=182345, q=900521 ncpus=2)
task:syz.0.4142      state:R  running task     stack:23608 pid:22523 tgid:22515 ppid:14572  task_flags:0x2040044c flags:0x00080001
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x17b4/0x5680 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/0x730 kernel/entry/common.c:164
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:is_bpf_text_address+0x0/0x2b0 kernel/bpf/core.c:744
Code: 3b 5b 00 be 00 02 00 00 bf 02 00 00 00 4c 89 ea e8 25 f5 55 ff 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <0f> 1f 40 d6 55 41 57 41 56 41 55 41 54 53 48 83 ec 10 49 89 fe e8
RSP: 0018:ffffc9000d1f65d0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 00007f6d24f9cdd9 RCX: 0000000000000046
RDX: 0000000000000002 RSI: ffffffff8e218a98 RDI: 00007f6d24f9cdd9
RBP: 0000000000000001 R08: ffffffff81af5add R09: ffffffff8e95cd60
R10: ffffc9000d1f6678 R11: ffffffff81b0e910 R12: ffff888035201ec0
R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff92001a3ecce
 kernel_text_address+0xa5/0xe0 kernel/extable.c:125
 __kernel_text_address+0xd/0x30 kernel/extable.c:79
 unwind_get_return_address+0x4d/0x90 arch/x86/kernel/unwind_orc.c:385
 arch_stack_walk+0xfb/0x150 arch/x86/kernel/stacktrace.c:26
 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:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4569 [inline]
 slab_alloc_node mm/slub.c:4898 [inline]
 kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4905
 kmem_alloc_batch lib/debugobjects.c:371 [inline]
 fill_pool+0x156/0x580 lib/debugobjects.c:420
 debug_objects_fill_pool lib/debugobjects.c:742 [inline]
 debug_object_activate+0x4a3/0x580 lib/debugobjects.c:831
 debug_rcu_head_queue kernel/rcu/rcu.h:236 [inline]
 __call_rcu_common kernel/rcu/tree.c:3116 [inline]
 call_rcu+0x43/0x890 kernel/rcu/tree.c:3251
 slab_free_hook mm/slub.c:2653 [inline]
 slab_free mm/slub.c:6250 [inline]
 kmem_cache_free+0x462/0x650 mm/slub.c:6377
 mempool_free+0xec/0x130 mm/mempool.c:711
 blk_update_request+0x57e/0xe60 block/blk-mq.c:1016
 blk_mq_end_request+0x3e/0x70 block/blk-mq.c:1178
 nullb_complete_cmd drivers/block/null_blk/main.c:1412 [inline]
 null_handle_cmd drivers/block/null_blk/main.c:1464 [inline]
 null_queue_rq+0xbfe/0xe30 drivers/block/null_blk/main.c:1703
 null_queue_rqs+0x123/0x270 drivers/block/null_blk/main.c:1717
 __blk_mq_flush_list block/blk-mq.c:2858 [inline]
 blk_mq_dispatch_queue_requests+0x417/0x800 block/blk-mq.c:2903
 blk_mq_flush_plug_list+0x456/0x570 block/blk-mq.c:2991
 blk_add_rq_to_plug+0x175/0x450 block/blk-mq.c:1417
 blk_mq_submit_bio+0x1acf/0x28e0 block/blk-mq.c:3245
 __submit_bio+0x1c0/0x580 block/blk-core.c:635
 __submit_bio_noacct_mq block/blk-core.c:722 [inline]
 submit_bio_noacct_nocheck+0x2f4/0xa40 block/blk-core.c:753
 __block_write_full_folio+0x810/0xe10 fs/buffer.c:1830
 blkdev_writepages+0xef/0x1b0 block/fops.c:486
 do_writepages+0x32e/0x550 mm/page-writeback.c:2571
 filemap_writeback mm/filemap.c:388 [inline]
 filemap_fdatawrite_range mm/filemap.c:413 [inline]
 filemap_write_and_wait_range+0x335/0x3f0 mm/filemap.c:685
 filemap_write_and_wait include/linux/pagemap.h:65 [inline]
 sync_blockdev block/bdev.c:276 [inline]
 bdev_release+0x192/0x650 block/bdev.c:1134
 blkdev_release+0x15/0x20 block/fops.c:705
 __fput+0x44f/0xa60 fs/file_table.c:510
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x70f/0x22c0 kernel/exit.c:975
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1117
 get_signal+0x1284/0x1330 kernel/signal.c:3037
 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x86/0x480 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:238 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6d24f9cdd9
RSP: 002b:00007f6d25de00e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f6d25216188 RCX: 00007f6d24f9cdd9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f6d25216188
RBP: 00007f6d25216180 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6d25216218 R14: 00007f6d2533f960 R15: 00007f6d2533fa48
 </TASK>
rcu: rcu_preempt kthread starved for 226 jiffies! g182345 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:27400 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x17b4/0x5680 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: 1337 Comm: kworker/u8:9 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:check_preemption_disabled+0x1/0xe0 lib/smp_processor_id.c:13
Code: 80 ac 28 8c 48 c7 c6 c0 ac 28 8c eb 1c 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 <41> 57 41 56 53 65 8b 05 b7 9f 90 07 65 8b 0d ac 9f 90 07 f7 c1 ff
RSP: 0018:ffffc90000a077a8 EFLAGS: 00000206
RAX: 0000000000000001 RBX: ffffffff90c98901 RCX: ffff888029561ec0
RDX: ffffc90000a07801 RSI: ffffffff8c28acc0 RDI: ffffffff8c28ac80
RBP: dffffc0000000000 R08: ffffc90000a079e0 R09: 0000000000000000
R10: ffffc90000a078f8 R11: fffff52000140f21 R12: ffffc90000a079f0
R13: ffffc90000a01000 R14: ffffc90000a078a8 R15: ffffffff8176f256
FS:  0000000000000000(0000) GS:ffff888125390000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f753523d356 CR3: 000000000e74a000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline]
 rcu_is_watching+0x15/0xb0 kernel/rcu/tree.c:752
 rcu_read_unlock include/linux/rcupdate.h:867 [inline]
 class_rcu_destructor include/linux/rcupdate.h:1181 [inline]
 unwind_next_frame+0x1b76/0x2550 arch/x86/kernel/unwind_orc.c:709
 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
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5419
 kmalloc_noprof include/linux/slab.h:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 ref_tracker_alloc+0x15a/0x4c0 lib/ref_tracker.c:270
 __netdev_tracker_alloc include/linux/netdevice.h:4471 [inline]
 netdev_hold include/linux/netdevice.h:4500 [inline]
 dst_init+0xd9/0x480 net/core/dst.c:52
 dst_alloc+0x12a/0x170 net/core/dst.c:94
 rt_dst_alloc net/ipv4/route.c:1651 [inline]
 __mkroute_output net/ipv4/route.c:2655 [inline]
 ip_route_output_key_hash_rcu+0x14d0/0x25d0 net/ipv4/route.c:2875
 ip_route_output_key_hash+0x18d/0x2a0 net/ipv4/route.c:2705
 __ip_route_output_key include/net/route.h:169 [inline]
 ip_route_output_flow+0x2a/0x150 net/ipv4/route.c:2932
 ip_route_output_key include/net/route.h:179 [inline]
 ip_route_me_harder+0x742/0xf90 net/ipv4/netfilter.c:54
 synproxy_send_tcp+0x34c/0x670 net/netfilter/nf_synproxy_core.c:432
 synproxy_send_client_synack+0x8c1/0xe30 net/netfilter/nf_synproxy_core.c:485
 nft_synproxy_eval_v4+0x34a/0x4e0 net/netfilter/nft_synproxy.c:60
 nft_synproxy_do_eval+0x305/0x580 net/netfilter/nft_synproxy.c:142
 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline]
 nft_do_chain+0x467/0x19f0 net/netfilter/nf_tables_core.c:285
 nft_do_chain_inet+0x360/0x4b0 net/netfilter/nft_chain_filter.c:162
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619
 nf_hook include/linux/netfilter.h:273 [inline]
 NF_HOOK+0x21f/0x3c0 include/linux/netfilter.h:316
 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318
 __netif_receive_skb_one_core net/core/dev.c:6202 [inline]
 __netif_receive_skb net/core/dev.c:6315 [inline]
 process_backlog+0xaa3/0x1950 net/core/dev.c:6666
 __napi_poll+0xae/0x340 net/core/dev.c:7730
 napi_poll net/core/dev.c:7793 [inline]
 net_rx_action+0x627/0xf70 net/core/dev.c:7950
 handle_softirqs+0x22a/0x840 kernel/softirq.c:622
 do_softirq+0x76/0xd0 kernel/softirq.c:523
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 __alloc_skb+0x1aa/0x7d0 net/core/skbuff.c:697
 alloc_skb include/linux/skbuff.h:1383 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:819 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:876 [inline]
 nsim_dev_trap_report_work+0x29a/0xb90 drivers/net/netdevsim/dev.c:922
 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>