rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-...!: (1 GPs behind) idle=f1e4/1/0x4000000000000000 softirq=88540/88543 fqs=3
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P16898
rcu: (detected by 1, t=10505 jiffies, g=81389, q=769 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 16898 Comm: syz.3.2721 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:26 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:109 [inline]
RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:151 [inline]
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:198
Code: 48 89 f3 49 89 fe 48 83 c7 18 48 8b 74 24 10 e8 85 6f e6 f5 4c 89 f7 e8 8d e4 e6 f5 f7 c3 00 02 00 00 74 05 e8 90 6f 12 f6 9c <58> a9 00 02 00 00 75 27 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00
RSP: 0018:ffffc90000007d20 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000096 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff9a6ccba0
RBP: ffff888056808c58 R08: ffffffff9a6ccba3 R09: 1ffffffff34d9974
R10: dffffc0000000000 R11: fffffbfff34d9975 R12: ffff888056808c50
R13: ffff888056808c40 R14: ffffffff9a6ccba0 R15: 1ffff1100ad0118a
FS: 00007f9e8d1d86c0(0000) GS:ffff888125213000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31b23ffc CR3: 000000007a102000 CR4: 00000000003526f0
Call Trace:
debug_object_activate+0x320/0x580 lib/debugobjects.c:853
debug_hrtimer_activate kernel/time/hrtimer.c:485 [inline]
debug_activate kernel/time/hrtimer.c:528 [inline]
enqueue_hrtimer+0xa9/0x2c0 kernel/time/hrtimer.c:1109
__run_hrtimer kernel/time/hrtimer.c:1946 [inline]
__hrtimer_run_queues+0x4d2/0xa20 kernel/time/hrtimer.c:1994
hrtimer_interrupt+0x44b/0x950 kernel/time/hrtimer.c:2113
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
__sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1067
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1061
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:get_current arch/x86/include/asm/current.h:25 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:245 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x8/0x90 kernel/kcov.c:314
Code: 89 44 11 20 e9 49 00 f6 09 cc 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 15 c8 fa 7a 11 65 8b 0d e9 fa 7a 11 81 e1 00 01 ff 00 74
RSP: 0018:ffffc9001012f620 EFLAGS: 00000297
RAX: ffffffff8994c026 RBX: ffff8880adc403c0 RCX: ffff88808d249ec0
RDX: 0000000000000002 RSI: 0000000000000401 RDI: 0000000000003ec0
RBP: ffff88805726c000 R08: ffff88808d249ec7 R09: 1ffff11011a493d8
R10: dffffc0000000000 R11: ffffffffa020178c R12: 0000000000000000
R13: 0000000000000401 R14: 0000000000000000 R15: dffffc0000000000
__bpf_skb_change_tail+0x206/0xb80 net/core/filter.c:-1
____bpf_skb_change_tail net/core/filter.c:3859 [inline]
bpf_skb_change_tail+0x34/0x1b0 net/core/filter.c:3856
bpf_prog_c5e8b7905b0ef9a4+0x59/0x62
bpf_dispatcher_nop_func include/linux/bpf.h:1402 [inline]
__bpf_prog_run include/linux/filter.h:722 [inline]
bpf_prog_run include/linux/filter.h:729 [inline]
bpf_test_run+0x354/0x830 net/bpf/test_run.c:423
bpf_prog_test_run_skb+0xe2c/0x2260 net/bpf/test_run.c:1192
bpf_prog_test_run+0x2c7/0x340 kernel/bpf/syscall.c:4742
__sys_bpf+0x643/0x950 kernel/bpf/syscall.c:6266
__do_sys_bpf kernel/bpf/syscall.c:6361 [inline]
__se_sys_bpf kernel/bpf/syscall.c:6359 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6359
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9e8c39cdd9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9e8d1d8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f9e8c615fa0 RCX: 00007f9e8c39cdd9
RDX: 0000000000000050 RSI: 00002000000003c0 RDI: 000000000000000a
RBP: 00007f9e8c432d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9e8c616038 R14: 00007f9e8c615fa0 R15: 00007fff5f3224e8
task:syz.3.2721 state:R running task stack:26688 pid:16898 tgid:16897 ppid:5850 task_flags:0x400140 flags:0x00080010
Call Trace:
rcu: rcu_preempt kthread starved for 10490 jiffies! g81389 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:27400 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5387 [inline]
__schedule+0x17b4/0x5680 kernel/sched/core.c:7188
__schedule_loop kernel/sched/core.c:7267 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7282
schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095
rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
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: 13988 Comm: kworker/u8:35 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: writeback wb_workfn (flush-8:0)
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0xfcf/0x13d0 kernel/smp.c:892
Code: 79 45 8b 2e 44 89 ee 83 e6 01 31 ff e8 fa fc 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 a5 f8 0b 00 eb 37 f3 90 <43> 0f b6 04 2c 84 c0 75 10 41 f7 06 01 00 00 00 74 1e e8 8a f8 0b
RSP: 0018:ffffc90006b1e220 EFLAGS: 00000293
RAX: ffffffff81b9d866 RBX: ffff8880b873c148 RCX: ffff888085eb8000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90006b1e350 R08: ffff8880345e5507 R09: 1ffff110068bcaa0
R10: dffffc0000000000 R11: ffffffff81790290 R12: 1ffff110170c8589
R13: dffffc0000000000 R14: ffff8880b8642c48 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888125313000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f036904f0d1 CR3: 00000000316f6000 CR4: 00000000003526f0
Call Trace:
on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1057
__flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline]
flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
flush_tlb_mm_range+0x5c3/0x10b0 arch/x86/mm/tlb.c:1451
flush_tlb_page arch/x86/include/asm/tlbflush.h:345 [inline]
ptep_clear_flush+0x120/0x170 mm/pgtable-generic.c:104
page_vma_mkclean_one+0x438/0x780 mm/rmap.c:1138
page_mkclean_one+0x1d8/0x2b0 mm/rmap.c:1186
__rmap_walk_file+0x467/0x620 mm/rmap.c:3062
rmap_walk mm/rmap.c:3106 [inline]
folio_mkclean+0x2bb/0x3d0 mm/rmap.c:1218
folio_clear_dirty_for_io+0x1a5/0x710 mm/page-writeback.c:2909
mpage_submit_folio+0x86/0x2b0 fs/ext4/inode.c:2084
mpage_process_page_bufs+0x6d5/0x8e0 fs/ext4/inode.c:2214
mpage_prepare_extent_to_map+0xe1b/0x16f0 fs/ext4/inode.c:2753
ext4_do_writepages+0xbac/0x4670 fs/ext4/inode.c:2894
ext4_writepages+0x241/0x3b0 fs/ext4/inode.c:3042
do_writepages+0x32e/0x550 mm/page-writeback.c:2575
__writeback_single_inode+0x133/0x10e0 fs/fs-writeback.c:1762
writeback_sb_inodes+0x979/0x19d0 fs/fs-writeback.c:2054
__writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2130
wb_writeback+0x459/0xb00 fs/fs-writeback.c:2241
wb_check_old_data_flush fs/fs-writeback.c:2345 [inline]
wb_do_writeback fs/fs-writeback.c:2398 [inline]
wb_workfn+0xb12/0xf10 fs/fs-writeback.c:2426
process_one_work kernel/workqueue.c:3302 [inline]
process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245