syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P8029/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=10265, q=2928343 ncpus=2)
task:syz.4.237       state:R  running task     stack:0     pid:8029  tgid:8026  ppid:6479   task_flags:0x40054c flags:0x0000000c
Call trace:
 __switch_to+0x414/0x788 arch/arm64/kernel/process.c:701 (T)
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x16a4/0x2c80 kernel/sched/core.c:6767
 preempt_schedule_common+0xe8/0x1dc kernel/sched/core.c:6947
 preempt_schedule+0x60/0x80 kernel/sched/core.c:6971
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x74/0x78 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 zap_pte_range mm/memory.c:1761 [inline]
 zap_pmd_range mm/memory.c:1823 [inline]
 zap_pud_range mm/memory.c:1852 [inline]
 zap_p4d_range mm/memory.c:1873 [inline]
 unmap_page_range+0x2b58/0x321c mm/memory.c:1894
 unmap_single_vma mm/memory.c:1940 [inline]
 unmap_vmas+0x378/0x598 mm/memory.c:1984
 exit_mmap+0x1f0/0xda4 mm/mmap.c:1284
 __mmput+0xec/0x3dc kernel/fork.c:1379
 mmput+0x70/0xac kernel/fork.c:1401
 exit_mm+0x148/0x210 kernel/exit.c:589
 do_exit+0x46c/0x1a20 kernel/exit.c:940
 do_group_exit+0x194/0x22c kernel/exit.c:1102
 get_signal+0x13e4/0x1500 kernel/signal.c:3034
 do_signal+0x22c/0x39f0 arch/arm64/kernel/signal.c:1615
 do_notify_resume+0x74/0x1f4 arch/arm64/kernel/entry-common.c:148
 exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline]
 el0_svc+0xac/0x168 arch/arm64/kernel/entry-common.c:745
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
rcu: rcu_preempt kthread starved for 1047 jiffies! g10265 f0x2 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:0     pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00000008
Call trace:
 __switch_to+0x414/0x788 arch/arm64/kernel/process.c:701 (T)
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x16a4/0x2c80 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0xbc/0x238 kernel/sched/core.c:6860
 schedule_timeout+0x164/0x2ac kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x2cc/0x16e8 kernel/rcu/tree.c:2046
 rcu_gp_kthread+0xc0/0x308 kernel/rcu/tree.c:2248
 kthread+0x674/0x7dc kernel/kthread.c:464
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 6 Comm: kworker/R-kvfre Not tainted 6.15.0-rc2-syzkaller-gc72692105976 #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: kvfree_rcu_reclaim kfree_rcu_monitor
pstate: 40400005 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __netif_receive_skb_core+0x33f8/0x3c30 net/core/dev.c:5844
lr : deliver_ptype_list_skb net/core/dev.c:2428 [inline]
lr : __netif_receive_skb_core+0x33b8/0x3c30 net/core/dev.c:5841
sp : ffff800080017720
x29: ffff8000800179e0 x28: ffff00005c136850 x27: ffff0000d04dc0d0
x26: dfff800000000000 x25: ffff800080017970 x24: ffff700010002f0c
x23: ffff800080017a80 x22: 000000000000ca88 x21: ffff80008ff59110
x20: ffff00005c136780 x19: 0000000000000008 x18: ffff0001fea918d8
x17: ffff800123885000 x16: ffff8000806abb64 x15: 0000000000000002
x14: 0000000000000000 x13: 000000000000a888 x12: ffff0000c19e1e80
x11: 0000000000ff0100 x10: 0000000000ff0100 x9 : 0000000000000000
x8 : 0000000000000000 x7 : ffff800089ac2dd8 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000002
x2 : ffff800080017aa0 x1 : 0000000000000008 x0 : 000000000000ca88
Call trace:
 __netif_receive_skb_core+0x33f8/0x3c30 net/core/dev.c:5844 (P)
 __netif_receive_skb_one_core net/core/dev.c:5883 [inline]
 __netif_receive_skb+0x114/0x3c8 net/core/dev.c:5998
 process_backlog+0x640/0x123c net/core/dev.c:6350
 __napi_poll+0xb4/0x3fc net/core/dev.c:7322
 napi_poll net/core/dev.c:7386 [inline]
 net_rx_action+0x6a8/0xf4c net/core/dev.c:7508
 handle_softirqs+0x320/0xd34 kernel/softirq.c:579
 __do_softirq+0x14/0x20 kernel/softirq.c:613
 ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:81
 call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:891
 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:86
 invoke_softirq kernel/softirq.c:460 [inline]
 __irq_exit_rcu+0x1d8/0x544 kernel/softirq.c:680
 irq_exit_rcu+0x14/0x84 kernel/softirq.c:696
 __el1_irq arch/arm64/kernel/entry-common.c:561 [inline]
 el1_interrupt+0x38/0x68 arch/arm64/kernel/entry-common.c:575
 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:580
 el1h_64_irq+0x6c/0x70 arch/arm64/kernel/entry.S:596
 __daif_local_irq_restore arch/arm64/include/asm/irqflags.h:175 [inline] (P)
 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:195 [inline] (P)
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline] (P)
 _raw_spin_unlock_irqrestore+0x44/0x98 kernel/locking/spinlock.c:194 (P)
 schedule_delayed_monitor_work+0x9c/0xb0 mm/slab_common.c:1665
 kfree_rcu_monitor+0x278/0x2b4 mm/slab_common.c:1783
 process_one_work+0x810/0x1638 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 rescuer_thread+0x59c/0xfa0 kernel/workqueue.c:3496
 kthread+0x674/0x7dc kernel/kthread.c:464
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862