syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 GPs behind) idle=e7f/1/0x4000000000000002 softirq=30862/30865 fqs=441 
	(detected by 1, t=10506 jiffies, g=35429, q=1113)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 9720 Comm: syz.0.5746 Not tainted 5.15.165-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
RIP: 0010:error_entry+0x16/0xf0 arch/x86/entry/entry_64.S:1011
Code: ff ff 85 db 0f 85 7a fe ff ff 0f 01 f8 e9 72 fe ff ff 66 90 56 48 8b 74 24 08 48 89 7c 24 08 52 51 50 41 50 41 51 41 52 41 53 <53> 55 41 54 41 55 41 56 41 57 56 31 d2 31 c9 45 31 c0 45 31 c9 45
RSP: 0000:ffffc9000353f888 EFLAGS: 00000006
RAX: 3d8232a0e54bc200 RBX: 1ffff920006a7f28 RCX: ffffffff81631a88
RDX: dffffc0000000000 RSI: ffffffff8a400e3b RDI: ffffffff8ad8f7c0
RBP: ffffc9000353f9d8 R08: dffffc0000000000 R09: fffffbfff20e1e19
R10: 0000000000000000 R11: dffffc0000000001 R12: ffffffff8c923c00
R13: ffff88807d8c3fd8 R14: ffffc9000353f940 R15: 1ffff920006a7f24
FS:  0000555556a8a500(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b3005ffff CR3: 0000000020276000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 </TASK>
rcu: rcu_preempt kthread starved for 8300 jiffies! g35429 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:27064 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 schedule+0x11b/0x1f0 kernel/sched/core.c:6456
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x2bf/0x1080 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2145
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 1
CPU: 1 PID: 3615 Comm: kworker/u4:0 Not tainted 5.15.165-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_check_gp_kthread_starvation+0x1d2/0x240 kernel/rcu/tree_stall.h:487
 print_other_cpu_stall+0x137a/0x14d0 kernel/rcu/tree_stall.h:592
 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
 rcu_pending kernel/rcu/tree.c:3932 [inline]
 rcu_sched_clock_irq+0xa38/0x1150 kernel/rcu/tree.c:2619
 update_process_times+0x196/0x200 kernel/time/timer.c:1818
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x386/0x550 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1686 [inline]
 __hrtimer_run_queues+0x55b/0xcf0 kernel/time/hrtimer.c:1750
 hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1812
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1085 [inline]
 __sysvec_apic_timer_interrupt+0x139/0x470 arch/x86/kernel/apic/apic.c:1102
 sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1096
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
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+0x1b4/0x200 arch/x86/kernel/kvm.c:918
Code: e0 48 c1 e8 03 42 0f b6 04 28 84 c0 75 42 45 0f b6 34 24 e8 8e de 4e 00 44 3a 74 24 1c 75 10 66 90 0f 00 2d 8e 7c 50 09 fb f4 <e9> c8 fe ff ff fb e9 c2 fe ff ff 44 89 e1 80 e1 07 38 c1 0f 8c 54
RSP: 0018:ffffc90002ec6360 EFLAGS: 00000246
RAX: d91776a95f5a6e00 RBX: 1ffff920005d8c70 RCX: ffffffff81631a88
RDX: dffffc0000000000 RSI: ffffffff8a8b2a20 RDI: ffffffff8ad8f7c0
RBP: ffffc90002ec6430 R08: dffffc0000000000 R09: fffffbfff20e1e19
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff888074bed120
R13: dffffc0000000000 R14: 0000000000000003 R15: ffffc90002ec63a0
 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+0x6bc/0xc40 kernel/locking/qspinlock.c:508
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline]
 queued_spin_lock_slowpath+0x42/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
 do_raw_spin_lock+0x269/0x370 kernel/locking/spinlock_debug.c:115
 page_vma_mapped_walk+0x15e0/0x18c0
 page_mkclean_one+0x340/0x7b0 mm/rmap.c:926
 rmap_walk_file+0x3f8/0x600 mm/rmap.c:2378
 rmap_walk mm/rmap.c:2396 [inline]
 page_mkclean+0x330/0x490 mm/rmap.c:1006
 clear_page_dirty_for_io+0x3ce/0xa60 mm/page-writeback.c:2749
 mpage_submit_page+0x90/0x230 fs/ext4/inode.c:2092
 mpage_process_page_bufs+0x6c8/0x8b0 fs/ext4/inode.c:2226
 mpage_prepare_extent_to_map+0xc9d/0x1150 fs/ext4/inode.c:2654
 ext4_writepages+0xcd0/0x3d10 fs/ext4/inode.c:2782
 do_writepages+0x481/0x730 mm/page-writeback.c:2386
 __writeback_single_inode+0x15b/0xe30 fs/fs-writeback.c:1647
 writeback_sb_inodes+0xbce/0x1a40 fs/fs-writeback.c:1930
 __writeback_inodes_wb+0x114/0x400 fs/fs-writeback.c:2001
 wb_writeback+0x465/0xc50 fs/fs-writeback.c:2106
 wb_check_old_data_flush fs/fs-writeback.c:2206 [inline]
 wb_do_writeback fs/fs-writeback.c:2259 [inline]
 wb_workfn+0xc55/0x1130 fs/fs-writeback.c:2288
 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>