rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4993/1:b..l
(detected by 0, t=10502 jiffies, g=10309, q=30)
task:syz.2.218 state:R running task stack:25424 pid: 4993 ppid: 4188 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11c3/0x4350 kernel/sched/core.c:6395
preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6571
preempt_schedule+0xbc/0xd0 kernel/sched/core.c:6596
preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
_raw_spin_unlock_irqrestore+0x10d/0x120 kernel/locking/spinlock.c:194
spin_unlock_irqrestore include/linux/spinlock.h:419 [inline]
__wake_up_common_lock kernel/sched/wait.c:140 [inline]
__wake_up_sync_key+0x128/0x190 kernel/sched/wait.c:205
sock_def_readable+0x136/0x250 net/core/sock.c:3100
__netlink_sendskb net/netlink/af_netlink.c:1260 [inline]
netlink_broadcast_deliver net/netlink/af_netlink.c:1397 [inline]
do_one_broadcast net/netlink/af_netlink.c:1489 [inline]
netlink_broadcast_filtered+0xcc3/0x1170 net/netlink/af_netlink.c:1533
netlink_broadcast+0x33/0x40 net/netlink/af_netlink.c:1557
uevent_net_broadcast_untagged lib/kobject_uevent.c:331 [inline]
kobject_uevent_net_broadcast+0x364/0x530 lib/kobject_uevent.c:409
kobject_uevent_env+0x550/0x890 lib/kobject_uevent.c:608
xprt_switch_alloc+0x41d/0x580 net/sunrpc/xprtmultipath.c:143
rpc_create_xprt+0x1c4/0x9c0 net/sunrpc/clnt.c:467
rpc_create+0x55f/0x7e0 net/sunrpc/clnt.c:604
nfs_create_rpc_client+0x4cc/0x6d0 fs/nfs/client.c:548
nfs4_alloc_client+0x6ea/0xa00 fs/nfs/nfs4client.c:240
nfs_get_client+0x9f4/0xd80 fs/nfs/client.c:447
nfs4_set_client+0x364/0x4e0 fs/nfs/nfs4client.c:936
nfs4_init_server fs/nfs/nfs4client.c:1145 [inline]
nfs4_create_server+0x4c0/0xe50 fs/nfs/nfs4client.c:1194
nfs4_try_get_tree+0x45/0x110 fs/nfs/nfs4super.c:226
vfs_get_tree+0x88/0x270 fs/super.c:1541
do_new_mount+0x247/0xa40 fs/namespace.c:3034
do_mount fs/namespace.c:3377 [inline]
__do_sys_mount fs/namespace.c:3585 [inline]
__se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3562
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fdbdc920159
RSP: 002b:00007fdbdab78028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fdbdcba7fa0 RCX: 00007fdbdc920159
RDX: 0000200000000400 RSI: 0000200000000100 RDI: 0000200000000300
RBP: 00007fdbdc9b706b R08: 0000200000000500 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdbdcba8038 R14: 00007fdbdcba7fa0 R15: 00007ffcde6d20b8
rcu: rcu_preempt kthread starved for 10502 jiffies! g10309 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:28112 pid: 15 ppid: 2 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11c3/0x4350 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
rcu_gp_fqs_loop+0x2be/0x11f0 kernel/rcu/tree.c:1972
rcu_gp_kthread+0x9a/0x370 kernel/rcu/tree.c:2145
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 0
CPU: 0 PID: 4994 Comm: syz.4.216 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
print_other_cpu_stall+0x1110/0x1270 kernel/rcu/tree_stall.h:592
check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
rcu_pending kernel/rcu/tree.c:3936 [inline]
rcu_sched_clock_irq+0x845/0x1120 kernel/rcu/tree.c:2619
update_process_times+0x193/0x200 kernel/time/timer.c:2021
tick_sched_handle kernel/time/tick-sched.c:254 [inline]
tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x4b0/0xb60 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x397/0x8b0 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__put_user_nocheck_4+0x3/0x11
Code: 00 00 48 39 d9 73 54 0f 01 cb 66 89 01 31 c9 0f 01 ca c3 90 90 90 90 90 48 bb fd ef ff ff ff 7f 00 00 48 39 d9 73 34 0f 01 cb <89> 01 31 c9 0f 01 ca c3 90 90 90 90 90 90 48 bb f9 ef ff ff ff 7f
RSP: 0018:ffffc900032afb38 EFLAGS: 00040206
RAX: 0000000000000003 RBX: 00007fb1bcacfe10 RCX: 00007fb1bcacfe40
RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900032afcb0 R08: 0000000000000000 R09: 1ffffffff17c7e65
R10: dffffc0000000000 R11: fffffbfff17c7e66 R12: 00007fb1bcacfc40
R13: dffffc0000000000 R14: 1ffff92000655f74 R15: 0000000000000000
save_xstate_epilog arch/x86/kernel/fpu/signal.c:131 [inline]
copy_fpstate_to_sigframe+0x9a9/0xba0 arch/x86/kernel/fpu/signal.c:217
get_sigframe arch/x86/kernel/signal.c:295 [inline]
__setup_rt_frame arch/x86/kernel/signal.c:471 [inline]
setup_rt_frame arch/x86/kernel/signal.c:780 [inline]
handle_signal arch/x86/kernel/signal.c:824 [inline]
arch_do_signal_or_restart+0x640/0x12a0 arch/x86/kernel/signal.c:869
handle_signal_work kernel/entry/common.c:157 [inline]
exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:181
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:217
__syscall_exit_to_user_mode_work kernel/entry/common.c:299 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:310
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fb1be899157
Code: 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 <0f> 05 48 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89
RSP: 002b:00007fb1bcad0028 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: 0000000000000028 RBX: 00007fb1beb21090 RCX: 00007fb1be899159
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 00007fb1be93006b R08: 0000000000000000 R09: 0000000000000000
R10: 0000020000023896 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb1beb21128 R14: 00007fb1beb21090 R15: 00007ffc7d321bb8