rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P59/1:b..l rcu: (detected by 0, t=10502 jiffies, g=41869, q=818 ncpus=1) task:kworker/u8:5 state:R running task stack:23464 pid:59 tgid:59 ppid:2 task_flags:0x24248060 flags:0x00080000 Workqueue: writeback wb_workfn (flush-8:0) Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7556 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x14f/0x8f0 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:deref_stack_reg arch/x86/kernel/unwind_orc.c:422 [inline] RIP: 0010:unwind_next_frame+0xcb7/0x2550 arch/x86/kernel/unwind_orc.c:614 Code: 4c 39 f8 0f 96 c0 20 c8 3c 01 0f 85 76 0e 00 00 48 89 d7 e8 eb 23 00 00 48 89 c3 49 bc 00 00 00 00 00 fc ff df 48 8b 44 24 20 <42> 80 3c 20 00 4d 8d 7e 48 74 08 4c 89 ff e8 e6 0f bd 00 49 89 1f RSP: 0018:ffffc9000200e6e0 EFLAGS: 00000202 RAX: 1ffff92000401cfa RBX: ffffffff825780af RCX: 1ffff92000401c01 RDX: ffffc9000200f6d8 RSI: 0000000000000002 RDI: ffffc9000200f6d8 RBP: 1ffffffff21ffdfa R08: ffffc9000200f6e0 R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff8eb59c60 R12: dffffc0000000000 R13: ffffc90002010000 R14: ffffc9000200e788 R15: ffffc90002008000 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:165 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320 reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1406 [inline] __free_frozen_pages+0xc1e/0xd10 mm/page_alloc.c:2950 __slab_free+0x274/0x2c0 mm/slub.c:5741 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:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4584 [inline] slab_alloc_node mm/slub.c:4917 [inline] kmem_cache_alloc_noprof+0x2a0/0x5f0 mm/slub.c:4931 ext4_init_io_end+0x29/0x130 fs/ext4/page-io.c:310 ext4_do_writepages+0xc06/0x47a0 fs/ext4/inode.c:2890 ext4_writepages+0x241/0x3b0 fs/ext4/inode.c:3043 do_writepages+0x338/0x560 mm/page-writeback.c:2571 __writeback_single_inode+0x12e/0xf90 fs/fs-writeback.c:1787 writeback_sb_inodes+0x9de/0x1b00 fs/fs-writeback.c:2079 __writeback_inodes_wb+0x114/0x240 fs/fs-writeback.c:2155 wb_writeback+0x42f/0xad0 fs/fs-writeback.c:2266 wb_check_old_data_flush fs/fs-writeback.c:2370 [inline] wb_do_writeback fs/fs-writeback.c:2449 [inline] wb_workfn+0xc92/0x10f0 fs/fs-writeback.c:2477 process_one_work kernel/workqueue.c:3322 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486 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 rcu: rcu_preempt kthread starved for 538 jiffies! g41869 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:27496 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7326 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325 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 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 3212 Comm: kworker/R-bat_e Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 Workqueue: bat_events batadv_tt_purge RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80 kernel/locking/spinlock.c:198 Code: f7 e8 2d 3d ce f5 f7 c3 00 02 00 00 74 05 e8 90 1d fa f5 9c 58 a9 00 02 00 00 75 27 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 c4 50 bf f5 65 8b 05 bd 50 98 07 85 c0 74 18 5b 41 5e e9 8c 21 RSP: 0018:ffffc90000007b08 EFLAGS: 00000206 RAX: 0000000000000006 RBX: 0000000000000246 RCX: 0000000080000101 RDX: 0000000000000002 RSI: ffffffff8e22ceab RDI: 0000000000000001 RBP: ffffc90000007e10 R08: ffffffff90578f37 R09: 1ffffffff20af1e6 R10: dffffc0000000000 R11: fffffbfff20af1e7 R12: 0000000000000246 R13: dffffc0000000000 R14: ffff88802a5fc000 R15: ffff88802a5ec410 FS: 0000000000000000(0000) GS:ffff888124f49000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5ce362c2e7 CR3: 0000000078e2c000 CR4: 0000000000350ef0 Call Trace: spin_unlock_irqrestore include/linux/spinlock.h:408 [inline] dummy_timer+0x497b/0x4cf0 drivers/usb/gadget/udc/dummy_hcd.c:-1 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x3bc/0xa10 kernel/time/hrtimer.c:2096 hrtimer_run_softirq+0x17a/0x240 kernel/time/hrtimer.c:2113 handle_softirqs+0x225/0x840 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0xca/0x220 kernel/softirq.c:735 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:should_resched arch/x86/include/asm/preempt.h:104 [inline] RIP: 0010:__local_bh_enable_ip+0xd8/0x130 kernel/softirq.c:457 Code: 8b e8 ec 03 4a 0a 65 66 8b 05 9c f0 e4 11 66 85 c0 75 32 bf 01 00 00 00 e8 85 f0 0b 00 e8 30 bd 46 00 fb 65 8b 05 78 f0 e4 11 <85> c0 75 05 e8 3f df aa ff 5b 41 5e e9 42 c1 87 ff cc 90 0f 0b 90 RSP: 0018:ffffc9000dba7a40 EFLAGS: 00000206 RAX: 0000000080000000 RBX: 0000000000000201 RCX: 0000000000000046 RDX: 0000000000000006 RSI: ffffffff8e22ceab RDI: ffffffff8c4bbf80 RBP: 0000000000000000 R08: ffffffff90578f37 R09: 1ffffffff20af1e6 R10: dffffc0000000000 R11: fffffbfff20af1e7 R12: dffffc0000000000 R13: ffff88807b5aaf08 R14: ffffffff8ba0fdce R15: ffff88807b5aaf10 spin_unlock_bh include/linux/spinlock.h:396 [inline] batadv_tt_global_purge net/batman-adv/translation-table.c:2301 [inline] batadv_tt_purge+0x4ae/0xa10 net/batman-adv/translation-table.c:3566 process_one_work kernel/workqueue.c:3322 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405 rescuer_thread+0x7b6/0x10b0 kernel/workqueue.c:3629 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