rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-...!: (1 ticks this GP) idle=5f9/1/0x4000000000000002 softirq=29293/29298 fqs=3
(detected by 1, t=10506 jiffies, g=41985, q=17)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 10212 Comm: syz.0.2144 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:__kasan_check_read+0x0/0x10 mm/kasan/shadow.c:31
Code: 41 5c 41 5d 41 5e 41 5f 5d c3 48 c7 c7 86 d9 de 8b eb 0a 48 c7 c7 80 fe c4 8b 48 89 de e8 d8 93 f3 07 31 ed eb d7 00 00 cc cc <89> f6 48 8b 0c 24 31 d2 e9 43 ef ff ff 0f 1f 00 89 f6 48 8b 0c 24
RSP: 0018:ffffc90002f4f620 EFLAGS: 00000046
RAX: ffffffff817f4f55 RBX: 0000000000000000 RCX: ffff8880234f1dc0
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8d89e368
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001200 CR3: 0000000022a2c000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
instrument_atomic_read include/linux/instrumented.h:71 [inline]
test_bit include/asm-generic/bitops/instrumented-non-atomic.h:134 [inline]
cpumask_test_cpu include/linux/cpumask.h:344 [inline]
cpu_online include/linux/cpumask.h:895 [inline]
trace_irq_disable include/trace/events/preemptirq.h:36 [inline]
trace_hardirqs_off_finish+0x9d/0x1f0 kernel/trace/trace_preemptirq.c:67
irqentry_enter+0x33/0x50 kernel/entry/common.c:384
sysvec_irq_work+0xa/0xc0 arch/x86/kernel/irq_work.c:17
asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 12 f2 9c 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc90002f4f720 EFLAGS: 00000206
RAX: 516ed785e6588c00 RBX: 1ffff920005e9ee8 RCX: 516ed785e6588c00
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f980
RBP: ffffc90002f4f7f0 R08: ffffffff901d40c7 R09: 1ffffffff203a818
R10: dffffc0000000000 R11: fffffbfff203a819 R12: ffffffff8c322f00
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
rcu_read_unlock include/linux/rcupdate.h:772 [inline]
__unlock_page_memcg+0xea/0x100 mm/memcontrol.c:2093
__set_page_dirty_buffers+0x2bf/0x4a0 fs/buffer.c:645
zap_pte_range mm/memory.c:1377 [inline]
zap_pmd_range mm/memory.c:1505 [inline]
zap_pud_range mm/memory.c:1534 [inline]
zap_p4d_range mm/memory.c:1555 [inline]
unmap_page_range+0xd5e/0x2500 mm/memory.c:1576
unmap_vmas+0x131/0x250 mm/memory.c:1653
exit_mmap+0x3b9/0x640 mm/mmap.c:3216
__mmput+0x115/0x3b0 kernel/fork.c:1127
exit_mm+0x588/0x6e0 kernel/exit.c:550
do_exit+0x5a9/0x20c0 kernel/exit.c:870
do_group_exit+0x12e/0x300 kernel/exit.c:997
__do_sys_exit_group kernel/exit.c:1008 [inline]
__se_sys_exit_group kernel/exit.c:1006 [inline]
__x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1006
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: 0033:0x7f3a61578799
Code: Unable to access opcode bytes at RIP 0x7f3a6157876f.
RSP: 002b:00007fff06b5bd08 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f3a61578799
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fff06b5bd6c R08: 0000000000000000 R09: 00000000000927c0
R10: 00007f3a617f2038 R11: 0000000000000246 R12: 000000000000014a
R13: 00000000000927c0 R14: 00000000000643d9 R15: 00007fff06b5bdc0
rcu: rcu_preempt kthread starved for 10490 jiffies! g41985 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:26960 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:2117
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 1
CPU: 1 PID: 1453 Comm: kworker/u4:4 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: writeback wb_workfn (flush-8:0)
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: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+0x4b4/0xb70 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:native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
RIP: 0010:kvm_wait+0x159/0x1b0 arch/x86/kernel/kvm.c:918
Code: 89 df 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 4b 0f b6 1f e8 77 b3 4a 00 44 38 e3 75 10 66 90 0f 00 2d 99 e2 f3 08 fb f4 16 ff ff ff fb e9 10 ff ff ff e8 47 cf 87 08 89 f9 80 e1 07 38
RSP: 0018:ffffc90006126800 EFLAGS: 00000246
RAX: c678b729cb6b6900 RBX: 0000000000000003 RCX: c678b729cb6b6900
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f980
RBP: ffffc900061268b0 R08: ffffffff901d40c7 R09: 1ffffffff203a818
R10: dffffc0000000000 R11: fffffbfff203a819 R12: 0000000000000003
R13: ffff8880b913b154 R14: dffffc0000000000 R15: 1ffff92000c24d00
pv_wait arch/x86/include/asm/paravirt.h:597 [inline]
pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
__pv_queued_spin_lock_slowpath+0x60f/0x9c0 kernel/locking/qspinlock.c:508
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline]
queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51
queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
do_raw_spin_lock+0x265/0x2f0 kernel/locking/spinlock_debug.c:115
page_vma_mapped_walk+0x1468/0x1740 mm/page_vma_mapped.c:-1
page_mkclean_one+0x17d/0x3e0 mm/rmap.c:926
rmap_walk_file+0x408/0x610 mm/rmap.c:2378
rmap_walk mm/rmap.c:2396 [inline]
page_mkclean+0x2f4/0x400 mm/rmap.c:1006
clear_page_dirty_for_io+0x3f8/0x9f0 mm/page-writeback.c:2749
mpage_submit_page+0x8a/0x210 fs/ext4/inode.c:2093
mpage_map_and_submit_buffers fs/ext4/inode.c:2361 [inline]
mpage_map_and_submit_extent fs/ext4/inode.c:2500 [inline]
ext4_writepages+0x1ae0/0x2df0 fs/ext4/inode.c:2829
do_writepages+0x476/0x6e0 mm/page-writeback.c:2386
__writeback_single_inode+0x153/0xda0 fs/fs-writeback.c:1657
writeback_sb_inodes+0xa4e/0x1680 fs/fs-writeback.c:1940
__writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:2011
wb_writeback+0x46f/0xbe0 fs/fs-writeback.c:2116
wb_check_old_data_flush fs/fs-writeback.c:2216 [inline]
wb_do_writeback fs/fs-writeback.c:2269 [inline]
wb_workfn+0xb15/0xf20 fs/fs-writeback.c:2298
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