rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-....: (1 ticks this GP) idle=cef4/1/0x4000000000000000 softirq=21931/21931 fqs=3
rcu: hardirqs softirqs csw/system
rcu: number: 2 0 4
rcu: cputime: 0 0 0 ==> 21700(ms)
rcu: (detected by 1, t=10506 jiffies, g=14121, q=2060 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6462 Comm: sed Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:debug_spin_lock_before kernel/locking/spinlock_debug.c:86 [inline]
RIP: 0010:do_raw_spin_lock+0x77/0x2b0 kernel/locking/spinlock_debug.c:115
Code: f1 f1 f1 c7 42 04 04 f3 f3 f3 65 48 8b 15 49 d3 e2 11 48 89 54 24 60 31 d2 48 89 fa 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 <83> c0 03 38 d0 7c 08 84 d2 0f 85 e4 01 00 00 8b 43 04 3d ad 4e ad
RSP: 0018:ffffc90000007cf8 EFLAGS: 00000002
RAX: 0000000000000004 RBX: ffff88807aef12e8 RCX: ffffffff938faa00
RDX: 0000000000000000 RSI: ffffffff8d800139 RDI: ffff88807aef12ec
RBP: 1ffff92000000fa0 R08: d75098bb7aa38fe9 R09: 0000000000000001
R10: 0000000000000002 R11: 0000000000000000 R12: ffff8880b8627c80
R13: 0000000000000000 R14: ffff88807aef1340 R15: ffffffff89686380
FS: 0000000000000000(0000) GS:ffff888124e78000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3760d33e9c CR3: 000000000df82000 CR4: 00000000003526f0
Call Trace:
spin_lock include/linux/spinlock.h:351 [inline]
advance_sched+0xd9/0xc80 net/sched/sch_taprio.c:929
__run_hrtimer kernel/time/hrtimer.c:1777 [inline]
__hrtimer_run_queues+0x202/0xad0 kernel/time/hrtimer.c:1841
hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1903
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline]
__sysvec_apic_timer_interrupt+0x108/0x3f0 arch/x86/kernel/apic/apic.c:1058
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1052
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:deref_stack_reg arch/x86/kernel/unwind_orc.c:403 [inline]
RIP: 0010:unwind_next_frame+0x83e/0x20a0 arch/x86/kernel/unwind_orc.c:573
Code: 00 fc ff df 48 8b 14 24 48 c1 ea 03 80 3c 02 00 0f 85 50 14 00 00 4d 8b 75 38 ba 08 00 00 00 4c 89 f6 4c 89 ef 4c 89 44 24 20 <48> 89 4c 24 18 4d 8d 7d 34 e8 a4 f5 ff ff 84 c0 0f 84 2e fb ff ff
RSP: 0018:ffffc90003c6f7a8 EFLAGS: 00000283
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff91009a48
RDX: 0000000000000008 RSI: ffffc90003c6fba8 RDI: ffffc90003c6f818
RBP: ffffc90003c6f860 R08: ffffffff91009a4c R09: 0000000000000000
R10: 0000000000000001 R11: 00000000000118b9 R12: ffffc90003c6f868
R13: ffffc90003c6f818 R14: ffffc90003c6fba8 R15: ffffc90003c6fbd0
arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:559
slab_free_hook mm/slub.c:2475 [inline]
slab_free mm/slub.c:6566 [inline]
kmem_cache_free+0x15e/0x6c0 mm/slub.c:6676
exit_mmap+0x50a/0xb90 mm/mmap.c:1305
__mmput+0x12a/0x410 kernel/fork.c:1133
mmput+0x62/0x70 kernel/fork.c:1156
exit_mm kernel/exit.c:582 [inline]
do_exit+0x7c7/0x2bf0 kernel/exit.c:954
do_group_exit+0xd3/0x2a0 kernel/exit.c:1107
__do_sys_exit_group kernel/exit.c:1118 [inline]
__se_sys_exit_group kernel/exit.c:1116 [inline]
__x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1116
x64_sys_call+0x150b/0x1730 arch/x86/include/generated/asm/syscalls_64.h:232
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x4e0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3760e926c5
Code: Unable to access opcode bytes at 0x7f3760e9269b.
RSP: 002b:00007ffc83992f08 EFLAGS: 00000206 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f3760f93fe8 RCX: 00007f3760e926c5
RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f3760f92680 R15: 00007f3760f94000
rcu: rcu_preempt kthread starved for 2115 jiffies! g14121 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:28232 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x1190/0x5de0 kernel/sched/core.c:6929
__schedule_loop kernel/sched/core.c:7011 [inline]
schedule+0xe7/0x3a0 kernel/sched/core.c:7026
schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083
rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285
kthread+0x3c2/0x780 kernel/kthread.c:463
ret_from_fork+0x56a/0x730 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 1091 Comm: kworker/u8:6 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: writeback wb_workfn (flush-8:0)
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0xdfd/0x1600 kernel/smp.c:877
Code: 57 48 8b 54 24 10 4c 89 74 24 10 49 89 d5 48 89 d5 48 89 54 24 18 49 c1 ed 03 83 e5 07 4d 01 e5 83 c5 03 e8 b5 0b 0c 00 f3 90 <41> 0f b6 45 00 40 38 c5 7c 08 84 c0 0f 85 e0 05 00 00 8b 43 08 31
RSP: 0018:ffffc90003cfe8b8 EFLAGS: 00000293
RAX: 0000000000000000 RBX: ffff8880b8642800 RCX: ffffffff81af2a21
RDX: ffff8880278e2480 RSI: ffffffff81af29fb RDI: 0000000000000005
RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: dffffc0000000000
R13: ffffed10170c8501 R14: 0000000000000001 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888124f78000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbe44a25e9c CR3: 000000000df82000 CR4: 00000000003526f0
Call Trace:
on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1043
__flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline]
flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
flush_tlb_mm_range+0x4a0/0x17a0 arch/x86/mm/tlb.c:1451
flush_tlb_page arch/x86/include/asm/tlbflush.h:324 [inline]
ptep_clear_flush+0x136/0x180 mm/pgtable-generic.c:101
page_vma_mkclean_one.constprop.0+0x3b4/0x7e0 mm/rmap.c:1041
page_mkclean_one+0x196/0x260 mm/rmap.c:1082
__rmap_walk_file+0x356/0x620 mm/rmap.c:2918
rmap_walk_file+0x174/0x1f0 mm/rmap.c:2951
rmap_walk mm/rmap.c:2962 [inline]
folio_mkclean+0x251/0x3f0 mm/rmap.c:1114
folio_clear_dirty_for_io+0x153/0x790 mm/page-writeback.c:2938
mpage_submit_folio+0x84/0x2d0 fs/ext4/inode.c:2061
mpage_map_and_submit_buffers+0x5c1/0xab0 fs/ext4/inode.c:2324
mpage_map_and_submit_extent fs/ext4/inode.c:2514 [inline]
ext4_do_writepages+0x2149/0x3cf0 fs/ext4/inode.c:2931
ext4_writepages+0x37a/0x7d0 fs/ext4/inode.c:3025
do_writepages+0x277/0x600 mm/page-writeback.c:2604
__writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1719
writeback_sb_inodes+0x60d/0xfa0 fs/fs-writeback.c:2015
__writeback_inodes_wb+0xf8/0x2d0 fs/fs-writeback.c:2086
wb_writeback+0x7f3/0xb70 fs/fs-writeback.c:2197
wb_check_old_data_flush fs/fs-writeback.c:2301 [inline]
wb_do_writeback fs/fs-writeback.c:2354 [inline]
wb_workfn+0x8ca/0xbe0 fs/fs-writeback.c:2382
process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
process_scheduled_works kernel/workqueue.c:3346 [inline]
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
kthread+0x3c2/0x780 kernel/kthread.c:463
ret_from_fork+0x56a/0x730 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245