rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P10088/1:b..l P10047/1:b..l P7984/1:b..l rcu: (detected by 0, t=10502 jiffies, g=41301, q=441 ncpus=2) task:kworker/u4:11 state:R running task stack:24520 pid:7984 ppid:2 flags:0x00004000 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet Call Trace: context_switch kernel/sched/core.c:5381 [inline] __schedule+0x1553/0x45a0 kernel/sched/core.c:6700 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010 irqentry_exit+0x67/0x70 kernel/entry/common.c:438 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:lock_acquire+0x208/0x420 kernel/locking/lockdep.c:5758 Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3c 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 43 c7 44 3c 08 00 00 00 00 65 48 8b 04 25 RSP: 0018:ffffc900036d78a0 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 0000000000000000 RCX: b449c04d17e5b200 RDX: 0000000000000000 RSI: ffffffff8acadae0 RDI: ffffffff8b1c85a0 RBP: ffffc900036d79a8 R08: dffffc0000000000 R09: 1ffffffff22382a0 R10: dffffc0000000000 R11: fffffbfff22382a1 R12: 1ffff920006daf20 R13: ffffffff8d132060 R14: 0000000000000246 R15: dffffc0000000000 rcu_lock_acquire include/linux/rcupdate.h:334 [inline] rcu_read_lock include/linux/rcupdate.h:786 [inline] batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:753 [inline] batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:824 [inline] batadv_iv_ogm_schedule+0x40b/0xf10 net/batman-adv/bat_iv_ogm.c:867 batadv_iv_send_outstanding_bat_ogm_packet+0x733/0x850 net/batman-adv/bat_iv_ogm.c:1711 process_one_work kernel/workqueue.c:2653 [inline] process_scheduled_works+0xa5d/0x15d0 kernel/workqueue.c:2730 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2811 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 task:syz.5.1131 state:R running task stack:24872 pid:10047 ppid:8854 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5381 [inline] __schedule+0x1553/0x45a0 kernel/sched/core.c:6700 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010 irqentry_exit+0x67/0x70 kernel/entry/common.c:438 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:692 RIP: 0010:lock_is_held_type+0x13e/0x190 kernel/locking/lockdep.c:5830 Code: 75 40 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 46 41 f7 c5 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 <48> 3b 44 24 08 75 3c 89 e8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f RSP: 0018:ffffc90003806f18 EFLAGS: 00000206 RAX: b4c7d6e14ad75900 RBX: ffff888023fe8000 RCX: b4c7d6e14ad75900 RDX: ffff888023fe8000 RSI: ffffffff8acadae0 RDI: ffffffff8b1c85a0 RBP: 0000000000000000 R08: dffffc0000000000 R09: 1ffffffff22382a0 R10: dffffc0000000000 R11: fffffbfff22382a1 R12: 0000000000000003 R13: 0000000000000246 R14: ffff88807be560a8 R15: ffff888023fe8b58 lock_is_held include/linux/lockdep.h:288 [inline] xa_entry include/linux/xarray.h:1216 [inline] xas_descend+0x107/0x490 lib/xarray.c:206 xas_load+0xbe/0x140 lib/xarray.c:244 filemap_get_entry+0x182/0x3f0 mm/filemap.c:1852 __filemap_get_folio+0x7c/0xbb0 mm/filemap.c:1897 simple_write_begin+0x61/0x840 fs/libfs.c:915 generic_perform_write+0x2fe/0x5c0 mm/filemap.c:4031 generic_file_write_iter+0xaf/0x2e0 mm/filemap.c:4152 __kernel_write_iter+0x28c/0x690 fs/read_write.c:517 dump_emit_page fs/coredump.c:957 [inline] dump_user_range+0x420/0x860 fs/coredump.c:984 elf_core_dump+0x31d0/0x3770 fs/binfmt_elf.c:2184 do_coredump+0x17cc/0x24d0 fs/coredump.c:833 get_signal+0x1133/0x13f0 kernel/signal.c:2888 arch_do_signal_or_restart+0xc2/0x800 arch/x86/kernel/signal.c:310 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 irqentry_exit_to_user_mode+0x9/0x30 kernel/entry/common.c:315 exc_page_fault+0x8c/0x100 arch/x86/mm/fault.c:1519 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608 RIP: 0033:0x7f6aa5a52777 RSP: 002b:00007f6aa69a8120 EFLAGS: 00010202 RAX: 0000000000000000 RBX: 000000000000000b RCX: 00007f6aa5b9c799 RDX: 00007f6aa69a8140 RSI: 00007f6aa69a8270 RDI: 000000000000000b RBP: 00007f6aa5c32c99 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 00007f6aa5e16038 R14: 00007f6aa5e15fa0 R15: 00007ffd30b759f8 task:syz.5.1136 state:R running task stack:24520 pid:10088 ppid:8854 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5381 [inline] __schedule+0x1553/0x45a0 kernel/sched/core.c:6700 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867 preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6891 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3a/0x40 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] wp_page_copy mm/memory.c:3202 [inline] do_wp_page+0x1f56/0x35f0 mm/memory.c:3469 handle_pte_fault mm/memory.c:5063 [inline] __handle_mm_fault mm/memory.c:5188 [inline] handle_mm_fault+0x135d/0x4c00 mm/memory.c:5353 faultin_page mm/gup.c:868 [inline] __get_user_pages+0x5d0/0x1380 mm/gup.c:1167 __get_user_pages_locked mm/gup.c:1431 [inline] __gup_longterm_locked+0x4de/0x2b80 mm/gup.c:2132 internal_get_user_pages_fast+0x21bf/0x2760 mm/gup.c:3227 io_pin_pages+0x92/0x170 io_uring/io_uring.c:2731 io_sqe_buffer_register+0x159/0x1910 io_uring/rsrc.c:892 io_sqe_buffers_register+0x3cb/0x520 io_uring/rsrc.c:1010 __io_uring_register io_uring/io_uring.c:4527 [inline] __do_sys_io_uring_register io_uring/io_uring.c:4704 [inline] __se_sys_io_uring_register+0x674/0xc50 io_uring/io_uring.c:4665 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f6aa5b9c799 RSP: 002b:00007f6aa6985028 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab RAX: ffffffffffffffda RBX: 00007f6aa5e16180 RCX: 00007f6aa5b9c799 RDX: 00002000000002c0 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 00007f6aa5c32c99 R08: 0000000000000000 R09: 0000000000000000 R10: 100000000000011a R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6aa5e16218 R14: 00007f6aa5e16180 R15: 00007ffd30b759f8 rcu: rcu_preempt kthread starved for 10385 jiffies! g41301 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:27312 pid:17 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5381 [inline] __schedule+0x1553/0x45a0 kernel/sched/core.c:6700 schedule+0xbd/0x170 kernel/sched/core.c:6774 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168 rcu_gp_fqs_loop+0x313/0x1590 kernel/rcu/tree.c:1667 rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:pv_native_safe_halt+0xf/0x10 arch/x86/kernel/paravirt.c:148 Code: 40 22 02 c3 cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d c3 29 43 00 fb f4 66 0f 1f 00 55 41 57 41 56 41 54 53 50 8b 2f eb 2e 41 89 de 80 RSP: 0018:ffffc90000187de0 EFLAGS: 000002c6 RAX: 9b7f570e00ec3a00 RBX: ffffffff8162ac40 RCX: 9b7f570e00ec3a00 RDX: 0000000000000001 RSI: ffffffff8acac960 RDI: ffffffff8b1c85a0 RBP: ffffc90000187f20 R08: ffff8880b8f36b2b R09: 1ffff110171e6d65 R10: dffffc0000000000 R11: ffffed10171e6d66 R12: 1ffff110036cd780 R13: 1ffff92000030fc8 R14: 0000000000000001 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1b9d4a76a2 CR3: 000000007af9a000 CR4: 00000000003506e0 DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000000083 DR3: ffffffffefffff15 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:753 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97 cpuidle_idle_call kernel/sched/idle.c:170 [inline] do_idle+0x1f0/0x4e0 kernel/sched/idle.c:282 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380 start_secondary+0xee/0xf0 arch/x86/kernel/smpboot.c:323 secondary_startup_64_no_verify+0x179/0x17b