rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4359/1:b..l P4348/1:b..l
(detected by 1, t=10503 jiffies, g=5565, q=82)
task:syz.0.12 state:R running task stack:24400 pid: 4348 ppid: 4182 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
__ext4_read_bh fs/ext4/super.c:156 [inline]
ext4_read_bh+0x180/0x240 fs/ext4/super.c:180
ext4_bread+0x12d/0x180 fs/ext4/inode.c:929
ext4_quota_write+0x230/0x570 fs/ext4/super.c:6596
write_blk fs/quota/quota_tree.c:64 [inline]
get_free_dqblk+0x387/0x7d0 fs/quota/quota_tree.c:125
do_insert_tree+0x214/0x1970 fs/quota/quota_tree.c:335
do_insert_tree+0x5b1/0x1970 fs/quota/quota_tree.c:366
dq_insert_tree fs/quota/quota_tree.c:392 [inline]
qtree_write_dquot+0x361/0x4b0 fs/quota/quota_tree.c:411
v2_write_dquot+0x108/0x190 fs/quota/quota_v2.c:358
dquot_acquire+0x2d5/0x520 fs/quota/dquot.c:472
ext4_acquire_dquot+0x2d9/0x4a0 fs/ext4/super.c:6205
dqget+0x778/0xeb0 fs/quota/dquot.c:988
__dquot_initialize+0x3b6/0xcb0 fs/quota/dquot.c:1517
ext4_file_open+0x2d1/0x6a0 fs/ext4/file.c:855
do_dentry_open+0x7ff/0xf80 fs/open.c:826
do_open fs/namei.c:3616 [inline]
path_openat+0x2682/0x2f30 fs/namei.c:3750
do_filp_open+0x1b3/0x3e0 fs/namei.c:3777
do_sys_openat2+0x142/0x4a0 fs/open.c:1253
do_sys_open fs/open.c:1269 [inline]
__do_sys_openat fs/open.c:1285 [inline]
__se_sys_openat fs/open.c:1280 [inline]
__x64_sys_openat+0x135/0x160 fs/open.c:1280
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: 0033:0x7f40c596b6c9
RSP: 002b:00007f40c3bd2038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f40c5bc1fa0 RCX: 00007f40c596b6c9
RDX: 00000000000c2042 RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 00007f40c59edf91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f40c5bc2038 R14: 00007f40c5bc1fa0 R15: 00007ffc5baa2c48
task:kworker/u4:11 state:R running task stack:27400 pid: 4359 ppid: 2 flags:0x00004000
Workqueue: loop0 loop_rootcg_workfn
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6799
irqentry_exit+0x63/0x70 kernel/entry/common.c:432
asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:681
RIP: 0010:lock_acquire+0x1f2/0x3f0 kernel/locking/lockdep.c:5627
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f6 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0018:ffffc9000333f560 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: f18ba851210fd400
RDX: 0000000000000000 RSI: ffffffff8a0b2f00 RDI: ffffffff8a59e580
RBP: ffffc9000333f680 R08: dffffc0000000000 R09: fffffbfff1ff7c19
R10: fffffbfff1ff7c19 R11: 1ffffffff1ff7c18 R12: ffffffff8c11c760
R13: 1ffff92000667eb8 R14: 0000000000000246 R15: dffffc0000000000
rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
rcu_read_lock include/linux/rcupdate.h:740 [inline]
aa_file_perm+0x114/0xe20 security/apparmor/file.c:611
common_file_perm+0x167/0x1c0 security/apparmor/lsm.c:475
security_file_permission+0x65/0xa0 security/security.c:1521
rw_verify_area fs/read_write.c:389 [inline]
do_iter_read+0x180/0x7c0 fs/read_write.c:785
lo_read_simple drivers/block/loop.c:392 [inline]
do_req_filebacked drivers/block/loop.c:663 [inline]
loop_handle_cmd drivers/block/loop.c:2235 [inline]
loop_process_work+0x18dc/0x2480 drivers/block/loop.c:2275
process_one_work+0x863/0x1000 kernel/workqueue.c:2310
worker_thread+0xaa8/0x12a0 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 10581 jiffies! g5565 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:28064 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: 4367 Comm: syz.2.14 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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:arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline]
RIP: 0010:static_key_false include/linux/jump_label.h:212 [inline]
RIP: 0010:native_write_msr arch/x86/include/asm/msr.h:156 [inline]
RIP: 0010:wrmsr arch/x86/include/asm/msr.h:263 [inline]
RIP: 0010:native_apic_msr_write+0x35/0x50 arch/x86/include/asm/apic.h:208
Code: 74 2a 83 ff 30 74 25 eb 10 81 ff d0 00 00 00 74 1b 81 ff e0 00 00 00 74 13 c1 ef 04 81 c7 00 08 00 00 89 f9 89 f0 31 d2 0f 30 <66> 90 c3 89 f6 31 d2 e9 3f c9 c7 02 66 2e 0f 1f 84 00 00 00 00 00
RSP: 0018:ffffc900032dfcb0 EFLAGS: 00000246
RAX: 00000000000000f6 RBX: ffffffff8bbcca20 RCX: 000000000000083f
RDX: 0000000000000000 RSI: 00000000000000f6 RDI: 000000000000083f
RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffed10172267af
R10: ffffed10172267af R11: 1ffff110172267ae R12: ffff8880b9133b01
R13: dffffc0000000000 R14: dffffc0000000000 R15: 0000000000000020
arch_irq_work_raise+0x82/0xd0 arch/x86/kernel/irq_work.c:31
irq_work_queue+0x95/0x140 kernel/irq_work.c:75
bpf_send_signal_common+0x2b2/0x420 kernel/trace/bpf_trace.c:820
____bpf_send_signal kernel/trace/bpf_trace.c:829 [inline]
bpf_send_signal+0x15/0x20 kernel/trace/bpf_trace.c:827
bpf_prog_7ba5217f62dcd359+0x38/0xf28
bpf_dispatcher_nop_func include/linux/bpf.h:888 [inline]
__bpf_prog_run include/linux/filter.h:628 [inline]
bpf_prog_run include/linux/filter.h:635 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:1878 [inline]
bpf_trace_run2+0x15b/0x2d0 kernel/trace/bpf_trace.c:1915
__bpf_trace_sys_enter+0x60/0x70 include/trace/events/syscalls.h:18
trace_sys_enter+0x65/0x80 include/trace/events/syscalls.h:18
syscall_trace_enter+0x115/0x180 kernel/entry/common.c:77
do_syscall_64+0x24/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f4236ef6779
Code: 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 90 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 c7 c0 0f 00 00 00 0f 05 <0f> 1f 80 00 00 00 00 48 81 ec 48 01 00 00 49 89 d0 64 48 8b 04 25
RSP: 002b:00007f42351c0a80 EFLAGS: 00000246 ORIG_RAX: 000000000000000f
RAX: ffffffffffffffda RBX: 00007f42371b0fa0 RCX: 00007f4236ef6779
RDX: 00007f42351c0a80 RSI: 00007f42351c0bb0 RDI: 0000000000000011
RBP: 00007f4236fdcf91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f42371b1038 R14: 00007f42371b0fa0 R15: 00007ffd7d3886e8