rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4211/1:b..l P4749/1:b..l
(detected by 0, t=10502 jiffies, g=9913, q=27)
task:syz.1.117 state:R running task stack:25360 pid: 4749 ppid: 4184 flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11ef/0x43c0 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_irq include/linux/spinlock_api_smp.h:169 [inline]
_raw_spin_unlock_irq+0x3c/0x40 kernel/locking/spinlock.c:202
spin_unlock_irq include/linux/spinlock.h:414 [inline]
loop_queue_work drivers/block/loop.c:1069 [inline]
loop_queue_rq+0x9e0/0xac0 drivers/block/loop.c:2202
__blk_mq_issue_directly block/blk-mq.c:2014 [inline]
__blk_mq_try_issue_directly+0x497/0x820 block/blk-mq.c:2070
blk_mq_request_issue_directly block/blk-mq.c:2118 [inline]
blk_mq_try_issue_list_directly+0x1a1/0x530 block/blk-mq.c:2136
blk_mq_sched_insert_requests+0x2d6/0x5c0 block/blk-mq-sched.c:512
blk_mq_flush_plug_list+0x59b/0x690 block/blk-mq.c:1971
blk_flush_plug_list+0x404/0x450 block/blk-core.c:1734
blk_finish_plug+0x59/0x80 block/blk-core.c:1751
__ext4_get_inode_loc+0x9d2/0xcd0 fs/ext4/inode.c:4420
ext4_get_inode_loc fs/ext4/inode.c:4456 [inline]
ext4_reserve_inode_write+0x140/0x2e0 fs/ext4/inode.c:5840
ext4_xattr_set_handle+0x4d5/0x12b0 fs/ext4/xattr.c:2362
ext4_set_context+0x22c/0x550 fs/ext4/super.c:1510
fscrypt_set_context+0x384/0x510 fs/crypto/policy.c:698
__ext4_new_inode+0x2e43/0x3a40 fs/ext4/ialloc.c:1323
ext4_mkdir+0x43f/0xce0 fs/ext4/namei.c:3066
vfs_mkdir+0x387/0x570 fs/namei.c:4073
do_mkdirat+0x1df/0x5b0 fs/namei.c:4098
__do_sys_mkdirat fs/namei.c:4113 [inline]
__se_sys_mkdirat fs/namei.c:4111 [inline]
__x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
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: 0033:0x7f9f94fb1b97
RSP: 002b:00007f9f9320de58 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f9f9320dee0 RCX: 00007f9f94fb1b97
RDX: 00000000000001ff RSI: 00002000000000c0 RDI: 00000000ffffff9c
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00002000000000c0
R13: 00007f9f9320dea0 R14: 0000000000000000 R15: 0000000000000000
task:kworker/u4:5 state:R running task stack:21464 pid: 4211 ppid: 2 flags:0x00004000
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
irqentry_exit+0x63/0x70 kernel/entry/common.c:432
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:INIT_LIST_HEAD include/linux/list.h:35 [inline]
RIP: 0010:batadv_iv_ogm_aggregate_new net/batman-adv/bat_iv_ogm.c:584 [inline]
RIP: 0010:batadv_iv_ogm_queue_add+0x992/0xcf0 net/batman-adv/bat_iv_ogm.c:670
Code: 48 c7 c2 40 05 6c 96 31 c9 45 31 c0 45 31 c9 6a 00 e8 d2 9b d2 f7 48 83 c4 08 4d 8d 74 24 50 4c 89 f0 48 c1 e8 03 80 3c 18 00 <74> 08 4c 89 f7 e8 d4 e1 33 f8 4d 89 74 24 50 49 8d 7c 24 58 48 89
RSP: 0018:ffffc9000305f980 EFLAGS: 00000246
RAX: 1ffff1100c47d78a RBX: dffffc0000000000 RCX: dffffc0000000000
RDX: 0000000000000010 RSI: 0000000000000000 RDI: ffff8880623ebc89
RBP: dffffc0000000000 R08: ffff8880623ebc7f R09: ffff8880623ebc70
R10: dffffc0000000000 R11: ffffed100c47d790 R12: ffff8880623ebc00
R13: ffff8880623ebc20 R14: ffff8880623ebc50 R15: ffff888019fe4c80
batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:849 [inline]
batadv_iv_ogm_schedule+0xae2/0xec0 net/batman-adv/bat_iv_ogm.c:868
batadv_iv_send_outstanding_bat_ogm_packet+0x72f/0x840 net/batman-adv/bat_iv_ogm.c:1712
process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
rcu: rcu_preempt kthread starved for 10314 jiffies! g9913 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:28016 pid: 15 ppid: 2 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_timeout+0x184/0x2d0 kernel/time/timer.c:1914
rcu_gp_fqs_loop+0x2be/0x11d0 kernel/rcu/tree.c:1972
rcu_gp_kthread+0x9b/0x370 kernel/rcu/tree.c:2145
kthread+0x436/0x520 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: 0 Comm: swapper/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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+0x843/0x1120 kernel/rcu/tree.c:2619
update_process_times+0x193/0x200 kernel/time/timer.c:1818
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+0x4ad/0xb70 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x3bb/0x8d0 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:default_idle+0xb/0x10 arch/x86/kernel/process.c:730
Code: b7 48 89 df e8 c6 9c fa f7 eb ad e8 4f b1 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 00 cc 66 90 0f 00 2d 67 4c 62 00 fb f4 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48
RSP: 0018:ffffffff8c007dc8 EFLAGS: 000002c6
RAX: d1af6b641345e800 RBX: ffffffff8c0bc480 RCX: d1af6b641345e800
RDX: 0000000000000001 RSI: ffffffff8a2b1c00 RDI: ffffffff8a79e740
RBP: ffffffff8c007ef8 R08: ffff8880b903b30b R09: 1ffff11017207661
R10: dffffc0000000000 R11: ffffed1017207662 R12: 1ffffffff1817890
R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffffffff1800fc4
default_idle_call+0x81/0xc0 kernel/sched/idle.c:112
cpuidle_idle_call kernel/sched/idle.c:194 [inline]
do_idle+0x21f/0x580 kernel/sched/idle.c:306
cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:403
start_kernel+0x489/0x540 init/main.c:1154
secondary_startup_64_no_verify+0xb1/0xbb