rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4358/1:b..l
(detected by 1, t=10502 jiffies, g=6261, q=39)
task:syz.1.16 state:R running task stack:26240 pid: 4358 ppid: 4180 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6571
preempt_schedule+0xa7/0xb0 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+0x497/0x810 block/blk-mq.c:2070
blk_mq_try_issue_directly+0xaf/0x270 block/blk-mq.c:2101
blk_mq_submit_bio+0xf17/0x17b0 block/blk-mq.c:-1
__submit_bio+0x7bd/0x810 block/blk-core.c:917
__submit_bio_noacct_mq block/blk-core.c:997 [inline]
submit_bio_noacct+0x5f1/0x6d0 block/blk-core.c:1027
submit_bio+0x2be/0x560 block/blk-core.c:1089
submit_bh+0x23/0x30 fs/buffer.c:3062
write_mmp_block_thawed+0x367/0x500 fs/ext4/mmp.c:51
ext4_multi_mount_protect+0x2d5/0x8f0 fs/ext4/mmp.c:367
ext4_fill_super+0x61d7/0x9a60 fs/ext4/super.c:4659
mount_bdev+0x287/0x3c0 fs/super.c:1400
legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
vfs_get_tree+0x88/0x270 fs/super.c:1530
do_new_mount+0x24a/0xa40 fs/namespace.c:3034
do_mount fs/namespace.c:3377 [inline]
__do_sys_mount fs/namespace.c:3585 [inline]
__se_sys_mount+0x2d6/0x3c0 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: 0033:0x7ff29a872eea
RSP: 002b:00007ff298ad7e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ff298ad7ef0 RCX: 00007ff29a872eea
RDX: 0000200000000040 RSI: 0000200000000000 RDI: 00007ff298ad7eb0
RBP: 0000200000000040 R08: 00007ff298ad7ef0 R09: 0000000003000046
R10: 0000000003000046 R11: 0000000000000246 R12: 0000200000000000
R13: 00007ff298ad7eb0 R14: 0000000000000564 R15: 000000000000002c
rcu: rcu_preempt kthread starved for 10538 jiffies! g6261 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:28224 pid: 15 ppid: 2 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
rcu_gp_kthread+0x98/0x350 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 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x397/0x3d0 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+0x10c8/0x1220 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+0x831/0x1110 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+0x4fe/0xc40 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: bf 48 89 df e8 c6 03 11 f8 eb b5 e8 ef b5 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 00 cc 66 90 0f 00 2d 17 93 5a 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:ffffc90000d67d48 EFLAGS: 000002c2
RAX: 9835383b29834d00 RBX: ffff88813fe40000 RCX: 9835383b29834d00
RDX: 0000000000000001 RSI: ffffffff8a0b1be0 RDI: ffffffff8a59e800
RBP: ffffc90000d67e80 R08: dffffc0000000000 R09: ffffed1017227662
R10: ffffed1017227662 R11: 1ffff11017227661 R12: ffffffff8d6935a8
R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff11027fc8000
default_idle_call+0x81/0xc0 kernel/sched/idle.c:112
cpuidle_idle_call kernel/sched/idle.c:194 [inline]
do_idle+0x21b/0x5b0 kernel/sched/idle.c:306
cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:403
start_secondary+0x31f/0x430 arch/x86/kernel/smpboot.c:281
secondary_startup_64_no_verify+0xb1/0xbb