rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=cb04/1/0x4000000000000000 softirq=50510/50511 fqs=3
rcu: 	(detected by 0, t=10502 jiffies, g=46625, q=259 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 12276 Comm: syz.0.2517 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:246 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x11/0x90 kernel/kcov.c:321
Code: cc cc 0f 1f 80 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 0c 25 08 40 c2 92 <65> 8b 15 18 e0 01 11 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75
RSP: 0018:ffffc90000a08c68 EFLAGS: 00000806
RAX: ffffffff89a5ccaa RBX: ffff888058d8cd28 RCX: ffff8880649b9e40
RDX: ffff8880649b9e40 RSI: 0000000000000000 RDI: 0000000000000010
RBP: 0000000000000001 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200014117c R12: dffffc0000000000
R13: ffff888058d8c8c0 R14: ffff888058d8c940 R15: 0000000000000000
FS:  00007ff168a586c0(0000) GS:ffff888125afc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff15d8ffc00 CR3: 0000000075518000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 advance_sched+0x51a/0xc90 net/sched/sch_taprio.c:966
 __run_hrtimer kernel/time/hrtimer.c:1777 [inline]
 __hrtimer_run_queues+0x52c/0xc60 kernel/time/hrtimer.c:1841
 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1058
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1052
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa8/0x110 kernel/locking/spinlock.c:194
Code: 74 05 e8 0b db 45 f6 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4f f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 43 65 0e f6 65 8b 05 dc 08 40 07 85 c0 74 40 48 c7 04 24 0e 36
RSP: 0018:ffffc900168a7600 EFLAGS: 00000206
RAX: f2244ab8d629f100 RBX: 0000000000000a06 RCX: f2244ab8d629f100
RDX: 0000000000000006 RSI: ffffffff8db9fb03 RDI: 0000000000000001
RBP: ffffc900168a7690 R08: ffffffff8fc35777 R09: 1ffffffff1f86aee
R10: dffffc0000000000 R11: fffffbfff1f86aef R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff88801c6a08d8 R15: 1ffff92002d14ec0
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 unlock_page_lruvec_irqrestore include/linux/memcontrol.h:1524 [inline]
 folio_batch_move_lru+0x37e/0x420 mm/swap.c:178
 __folio_batch_add_and_move+0x51c/0xc60 mm/swap.c:196
 shmem_alloc_and_add_folio+0xcb3/0xf60 mm/shmem.c:1969
 shmem_get_folio_gfp+0x59d/0x1660 mm/shmem.c:2533
 shmem_get_folio mm/shmem.c:2639 [inline]
 shmem_write_begin+0xf7/0x2b0 mm/shmem.c:3289
 generic_perform_write+0x2c5/0x900 mm/filemap.c:4242
 shmem_file_write_iter+0xf8/0x120 mm/shmem.c:3464
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x5c9/0xb30 fs/read_write.c:686
 ksys_write+0x145/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff167b8d97f
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48
RSP: 002b:00007ff168a57df0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000100000 RCX: 00007ff167b8d97f
RDX: 0000000000100000 RSI: 00007ff15d800000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000c47
R10: 0000200000001b42 R11: 0000000000000293 R12: 0000000000000003
R13: 00007ff168a57ef0 R14: 00007ff168a57eb0 R15: 00007ff15d800000
 </TASK>
rcu: rcu_preempt kthread starved for 10496 jiffies! g46625 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:27224 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7026
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 13 Comm: kworker/u8:1 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+0xd33/0x12d0 kernel/smp.c:877
Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 96 73 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 41 6f 0b 00 eb 38 f3 90 <42> 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 25 6f
RSP: 0018:ffffc90000126040 EFLAGS: 00000293
RAX: ffffffff81b4ebfb RBX: 1ffff110170e7ffd RCX: ffff88801d688000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900001261c0 R08: ffff888031440a07 R09: 1ffff11006288140
R10: dffffc0000000000 R11: ffffffff817629e0 R12: ffff8880b873ffe8
R13: dffffc0000000000 R14: ffff8880b863b200 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8881259fc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f994d83ff98 CR3: 000000003322e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80 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+0x6b1/0x12d0 arch/x86/mm/tlb.c:1451
 flush_tlb_page arch/x86/include/asm/tlbflush.h:324 [inline]
 ptep_clear_flush+0x120/0x170 mm/pgtable-generic.c:101
 page_vma_mkclean_one+0x406/0x740 mm/rmap.c:1041
 page_mkclean_one+0x1c0/0x280 mm/rmap.c:1082
 __rmap_walk_file+0x467/0x620 mm/rmap.c:2918
 rmap_walk mm/rmap.c:2962 [inline]
 folio_mkclean+0x297/0x390 mm/rmap.c:1114
 folio_clear_dirty_for_io+0x1f5/0x880 mm/page-writeback.c:2938
 mpage_submit_folio+0x86/0x2b0 fs/ext4/inode.c:2061
 mpage_process_page_bufs+0x6d5/0x8e0 fs/ext4/inode.c:2191
 mpage_prepare_extent_to_map+0xe6c/0x16e0 fs/ext4/inode.c:2736
 ext4_do_writepages+0xba0/0x4610 fs/ext4/inode.c:2877
 ext4_writepages+0x205/0x350 fs/ext4/inode.c:3025
 do_writepages+0x32e/0x550 mm/page-writeback.c:2604
 __writeback_single_inode+0x145/0xff0 fs/fs-writeback.c:1719
 writeback_sb_inodes+0x6c7/0x1010 fs/fs-writeback.c:2015
 __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2086
 wb_writeback+0x44f/0xaf0 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+0xaef/0xef0 fs/fs-writeback.c:2382
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>