syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4311/1:b..l P571/1:b..l P3912/1:b..l
	(detected by 0, t=10502 jiffies, g=5809, q=239 ncpus=2)
task:udevd           state:R  running task     stack:0     pid:3912  ppid:1      flags:0x00000004
Call trace:
 __switch_to+0x2f4/0x568 arch/arm64/kernel/process.c:555
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0xdd4/0x1b2c kernel/sched/core.c:6561
 preempt_schedule_common+0xec/0x1a0 kernel/sched/core.c:6730
 preempt_schedule+0x64/0x84 kernel/sched/core.c:6754
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0xa8/0xac kernel/locking/spinlock.c:194
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 __wake_up_common_lock kernel/sched/wait.c:140 [inline]
 __wake_up_sync_key+0x11c/0x178 kernel/sched/wait.c:208
 sock_def_readable+0x150/0x278 net/core/sock.c:3308
 __netlink_sendskb net/netlink/af_netlink.c:1258 [inline]
 netlink_sendskb+0xa4/0x164 net/netlink/af_netlink.c:1264
 netlink_unicast+0x2d0/0x818 net/netlink/af_netlink.c:1352
 netlink_sendmsg+0x6e8/0x9b0 net/netlink/af_netlink.c:1859
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x5b8/0x918 net/socket.c:2519
 ___sys_sendmsg net/socket.c:2573 [inline]
 __sys_sendmsg+0x25c/0x320 net/socket.c:2602
 __do_sys_sendmsg net/socket.c:2611 [inline]
 __se_sys_sendmsg net/socket.c:2609 [inline]
 __arm64_sys_sendmsg+0x80/0x94 net/socket.c:2609
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
task:kworker/u4:5    state:R  running task     stack:0     pid:571   ppid:2      flags:0x00000008
Workqueue: bat_events batadv_nc_worker
Call trace:
 __switch_to+0x2f4/0x568 arch/arm64/kernel/process.c:555
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0xdd4/0x1b2c kernel/sched/core.c:6561
 preempt_schedule_irq+0x8c/0x1b8 kernel/sched/core.c:6873
 arm64_preempt_schedule_irq+0x44/0x58 arch/arm64/kernel/entry-common.c:265
 __el1_irq arch/arm64/kernel/entry-common.c:474 [inline]
 el1_interrupt+0x3c/0x54 arch/arm64/kernel/entry-common.c:486
 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:491
 el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:581
 preempt_count arch/arm64/include/asm/preempt.h:13 [inline]
 check_kcov_mode kernel/kcov.c:182 [inline]
 write_comp_data kernel/kcov.c:245 [inline]
 __sanitizer_cov_trace_const_cmp4+0x14/0xb0 kernel/kcov.c:313
 process_one_work+0x7f4/0x13a8 kernel/workqueue.c:2292
 worker_thread+0x8c8/0xfbc kernel/workqueue.c:2439
 kthread+0x250/0x2d8 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:849
task:udevd           state:R  running task     stack:0     pid:4311  ppid:3912   flags:0x00000004
Call trace:
 __switch_to+0x2f4/0x568 arch/arm64/kernel/process.c:555
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0xdd4/0x1b2c kernel/sched/core.c:6561
 preempt_schedule_common+0xec/0x1a0 kernel/sched/core.c:6730
 preempt_schedule+0x64/0x84 kernel/sched/core.c:6754
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x80/0x84 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 __d_lookup+0x528/0x6a8 fs/dcache.c:2506
 lookup_fast+0x78/0x43c fs/namei.c:1648
 walk_component fs/namei.c:1994 [inline]
 link_path_walk+0x518/0xc6c fs/namei.c:2325
 path_openat+0x1c0/0x2680 fs/namei.c:3779
 do_filp_open+0x174/0x344 fs/namei.c:3810
 do_sys_openat2+0x128/0x3d8 fs/open.c:1318
 do_sys_open fs/open.c:1334 [inline]
 __do_sys_openat fs/open.c:1350 [inline]
 __se_sys_openat fs/open.c:1345 [inline]
 __arm64_sys_openat+0x120/0x154 fs/open.c:1345
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
rcu: rcu_preempt kthread starved for 10507 jiffies! g5809 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:0     pid:16    ppid:2      flags:0x00000008
Call trace:
 __switch_to+0x2f4/0x568 arch/arm64/kernel/process.c:555
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0xdd4/0x1b2c kernel/sched/core.c:6561
 schedule+0xc4/0x170 kernel/sched/core.c:6637
 schedule_timeout+0x180/0x2c8 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2a8/0x134c kernel/rcu/tree.c:1706
 rcu_gp_kthread+0xc0/0x2f8 kernel/rcu/tree.c:1905
 kthread+0x250/0x2d8 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:849
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 4472 Comm: syz.0.16 Not tainted 6.1.142-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : do_notify_resume+0x118/0x2b0c arch/arm64/kernel/signal.c:1127
lr : local_daif_restore arch/arm64/include/asm/daifflags.h:75 [inline]
lr : do_notify_resume+0x10c/0x2b0c arch/arm64/kernel/signal.c:1122
sp : ffff800020f57be0
x29: ffff800020f57e10 x28: ffff0000d1858000 x27: 0000000000000000
x26: dfff800000000000 x25: 0000000000000001 x24: 1fffe0001a30b000
x23: 0000000080001000 x22: ffff800020f57d20 x21: ffff800020f57eb0
x20: ffff800020f57fc8 x19: ffff800020f57fb0 x18: 0000000000000000
x17: 0000000000000000 x16: ffff8000082d2400 x15: 0000ffffdae3d580
x14: 0000000000000000 x13: 1ffff00002a100b1 x12: 0000000000ff0100
x11: ff0080000a88b400 x10: 0000000000000000 x9 : ffff80000a88b400
x8 : 0000000001df931b x7 : 0000000000000000 x6 : ffff800020f57638
x5 : ffff800020f57638 x4 : 0000000000000000 x3 : 0000000000000000
x2 : ffff800020f57b20 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
 local_daif_restore arch/arm64/include/asm/daifflags.h:117 [inline]
 do_notify_resume+0x118/0x2b0c arch/arm64/kernel/signal.c:1122
 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
 el0_svc+0x98/0x138 arch/arm64/kernel/entry-common.c:638
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585