rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P49/2:b..l rcu: (detected by 1, t=10503 jiffies, g=94573, q=3701 ncpus=2) task:kworker/u8:3 state:R running task stack:23368 pid:49 tgid:49 ppid:2 task_flags:0x24208160 flags:0x00004000 Workqueue: writeback wb_workfn (flush-250:0) Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6961 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7288 irqentry_exit+0x36/0x90 kernel/entry/common.c:197 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:lock_release+0x183/0x2f0 kernel/locking/lockdep.c:5893 Code: 0f c1 05 38 3e 3e 12 83 f8 01 0f 85 1d 01 00 00 9c 58 f6 c4 02 0f 85 08 01 00 00 41 f7 c5 00 02 00 00 74 01 fb 48 8b 44 24 10 <65> 48 2b 05 4d fc 3d 12 0f 85 58 01 00 00 48 83 c4 18 5b 41 5c 41 RSP: 0018:ffffc90000b966d0 EFLAGS: 00000206 RAX: 3b3eba0f4d09c500 RBX: ffffffff8e5c1160 RCX: ffffc90000b966dc RDX: 0000000000000004 RSI: ffffffff8de29498 RDI: ffffffff8c161180 RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000004 R11: 000000000003c3d8 R12: ffffffff816ae8a4 R13: 0000000000000202 R14: ffff88801eaf2440 R15: 0000000000000005 rcu_lock_release include/linux/rcupdate.h:341 [inline] rcu_read_unlock include/linux/rcupdate.h:871 [inline] class_rcu_destructor include/linux/rcupdate.h:1155 [inline] unwind_next_frame+0x3f9/0x20a0 arch/x86/kernel/unwind_orc.c:479 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 poison_kmalloc_redzone mm/kasan/common.c:388 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:405 kmalloc_noprof include/linux/slab.h:905 [inline] slab_free_hook mm/slub.c:2369 [inline] slab_free mm/slub.c:4680 [inline] kmem_cache_free+0x142/0x4d0 mm/slub.c:4782 mempool_free+0x102/0x750 mm/mempool.c:576 bio_put_percpu_cache block/bio.c:801 [inline] bio_put+0x355/0x5b0 block/bio.c:820 bio_endio+0x70a/0x850 block/bio.c:1651 blk_update_request+0x93e/0x15f0 block/blk-mq.c:989 blk_mq_end_request+0x5b/0x630 block/blk-mq.c:1151 blk_mq_complete_request block/blk-mq.c:1329 [inline] blk_mq_complete_request+0x88/0xb0 block/blk-mq.c:1326 nullb_complete_cmd drivers/block/null_blk/main.c:1402 [inline] null_handle_cmd drivers/block/null_blk/main.c:1454 [inline] null_queue_rq+0xb69/0xfd0 drivers/block/null_blk/main.c:1693 null_queue_rqs+0xe9/0x2f0 drivers/block/null_blk/main.c:1707 __blk_mq_flush_list block/blk-mq.c:2828 [inline] __blk_mq_flush_list+0x9a/0xc0 block/blk-mq.c:2824 blk_mq_dispatch_queue_requests+0x184/0x7b0 block/blk-mq.c:2873 blk_mq_flush_plug_list+0x1f2/0x600 block/blk-mq.c:2961 blk_add_rq_to_plug+0x1ca/0x540 block/blk-mq.c:1390 blk_mq_submit_bio+0x1a1c/0x2880 block/blk-mq.c:3212 __submit_bio+0x3cf/0x690 block/blk-core.c:635 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x660/0xd30 block/blk-core.c:751 submit_bio_noacct+0xb49/0x1eb0 block/blk-core.c:874 __block_write_full_folio+0x735/0xe00 fs/buffer.c:1933 block_write_full_folio+0x341/0x400 fs/buffer.c:2753 blkdev_writepages+0xb8/0x140 block/fops.c:483 do_writepages+0x27a/0x600 mm/page-writeback.c:2634 __writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1680 writeback_sb_inodes+0x60d/0xfa0 fs/fs-writeback.c:1976 __writeback_inodes_wb+0xf8/0x2d0 fs/fs-writeback.c:2047 wb_writeback+0x7f3/0xb70 fs/fs-writeback.c:2158 wb_check_old_data_flush fs/fs-writeback.c:2262 [inline] wb_do_writeback fs/fs-writeback.c:2315 [inline] wb_workfn+0x8ca/0xbe0 fs/fs-writeback.c:2343 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3236 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c5/0x780 kernel/kthread.c:463 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: rcu_preempt kthread starved for 729 jiffies! g94573 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:27392 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:7058 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2285 kthread+0x3c5/0x780 kernel/kthread.c:463 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: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 22326 Comm: kworker/u8:20 Not tainted 6.16.0-syzkaller-12063-g37816488247d #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Workqueue: wg-kex-wg0 wg_packet_handshake_send_worker RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline] RIP: 0010:rcu_is_watching+0x12/0xc0 kernel/rcu/tree.c:751 Code: 84 00 00 00 00 00 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 53 65 ff 05 f3 0c 35 12 e8 5e 11 f2 09 <48> c7 c3 a8 f2 d6 93 89 c5 83 f8 07 0f 87 82 00 00 00 48 8d 3c ed RSP: 0018:ffffc90000007950 EFLAGS: 00000296 RAX: 0000000000000000 RBX: ffff8880807b4880 RCX: ffffffff896f5de7 RDX: 0000000000000001 RSI: ffffffff8c161100 RDI: ffffffff8c161140 RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffffc90000007bf0 R13: 0000000000000001 R14: ffff8881d798b640 R15: ffff8881d798b640 FS: 0000000000000000(0000) GS:ffff8881246c4000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffffffffffffd CR3: 00000000433cd000 CR4: 00000000003526f0 Call Trace: rcu_read_lock_held_common kernel/rcu/update.c:109 [inline] rcu_read_lock_held+0x1e/0x50 kernel/rcu/update.c:349 read_pnet_rcu include/net/net_namespace.h:418 [inline] dev_net_rcu include/linux/netdevice.h:2721 [inline] __netif_receive_skb_core.constprop.0+0x2452/0x48c0 net/core/dev.c:5811 __netif_receive_skb_one_core+0xb0/0x1e0 net/core/dev.c:5977 __netif_receive_skb+0x1d/0x160 net/core/dev.c:6092 process_backlog+0x442/0x15e0 net/core/dev.c:6444 __napi_poll.constprop.0+0xb7/0x550 net/core/dev.c:7489 napi_poll net/core/dev.c:7552 [inline] net_rx_action+0xa9f/0xfe0 net/core/dev.c:7679 handle_softirqs+0x216/0x8e0 kernel/softirq.c:579 do_softirq kernel/softirq.c:480 [inline] do_softirq+0xb2/0xf0 kernel/softirq.c:467 __local_bh_enable_ip+0x100/0x120 kernel/softirq.c:407 local_bh_enable include/linux/bottom_half.h:33 [inline] fpregs_unlock arch/x86/include/asm/fpu/api.h:77 [inline] kernel_fpu_end+0x5e/0x70 arch/x86/kernel/fpu/core.c:479 blake2s_compress+0x7f/0xe0 lib/crypto/x86/blake2s-glue.c:46 blake2s_update+0xef/0x360 lib/crypto/blake2s.c:33 hmac.constprop.0+0x32a/0x420 drivers/net/wireguard/noise.c:332 kdf.constprop.0+0x14b/0x280 drivers/net/wireguard/noise.c:367 message_ephemeral+0x5f/0x70 drivers/net/wireguard/noise.c:493 wg_noise_handshake_create_initiation+0x2c6/0x650 drivers/net/wireguard/noise.c:545 wg_packet_send_handshake_initiation+0x19a/0x360 drivers/net/wireguard/send.c:34 wg_packet_handshake_send_worker+0x1c/0x30 drivers/net/wireguard/send.c:51 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3236 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 batman_adv: batadv0: Local translation table size (108) exceeds maximum packet size (-320); Ignoring new local tt entry: aa:aa:aa:aa:aa:17 batman_adv: batadv0: Local translation table size (108) exceeds maximum packet size (-320); Ignoring new local tt entry: aa:aa:aa:aa:aa:17 tipc: Duplicate ac1414aa using udp(172.20.20.170:20002) seen on batman_adv: batadv0: Local translation table size (108) exceeds maximum packet size (-320); Ignoring new local tt entry: aa:aa:aa:aa:aa:17 batman_adv: batadv0: Local translation table size (108) exceeds maximum packet size (-320); Ignoring new local tt entry: aa:aa:aa:aa:aa:17 batman_adv: batadv0: Local translation table size (108) exceeds maximum packet size (-320); Ignoring new local tt entry: aa:aa:aa:aa:aa:17