syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P9334/1:b..l
	(detected by 1, t=10502 jiffies, g=82097, q=134)
task:syz.0.1492      state:R  running task     stack:21496 pid: 9334 ppid:  7836 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6780
 irqentry_exit+0x53/0x80 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:rcu_read_lock_held_common kernel/rcu/update.c:112 [inline]
RIP: 0010:rcu_read_lock_held+0x15/0x40 kernel/rcu/update.c:309
Code: 00 00 00 00 00 e8 4b f4 00 00 e9 e6 f5 00 00 66 0f 1f 44 00 00 53 e8 6a bf c8 08 85 c0 74 26 31 db e8 7f c4 00 00 84 c0 74 20 <e8> d6 c5 00 00 84 c0 74 17 48 c7 c7 20 fb 91 8c be ff ff ff ff 5b
RSP: 0018:ffffc90003037440 EFLAGS: 00000202
RAX: 000000000005a101 RBX: 0000000000000000 RCX: ffff8880602ed940
RDX: ffff8880602ed940 RSI: ffffffff8ad8f7e0 RDI: ffffffff8ad8f7a0
RBP: ffff888018cacf50 R08: ffffffff842fe23d R09: fffffbfff1f8e019
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff92000606ea8
R13: 0000000000000006 R14: ffff88801205f182 R15: ffffc90003037540
 xa_entry include/linux/xarray.h:1182 [inline]
 xas_descend+0x118/0x3a0 lib/xarray.c:204
 xas_load+0xba/0x140 lib/xarray.c:240
 mapping_get_entry mm/filemap.c:1826 [inline]
 pagecache_get_page+0x20f/0x1010 mm/filemap.c:1894
 find_get_page_flags include/linux/pagemap.h:357 [inline]
 __find_get_block_slow fs/buffer.c:202 [inline]
 __find_get_block+0x3e8/0x1350 fs/buffer.c:1310
 __getblk_slow fs/buffer.c:1037 [inline]
 __getblk_gfp+0x164/0xaf0 fs/buffer.c:1336
 __bread_gfp+0x2a/0x390 fs/buffer.c:1381
 sb_bread include/linux/buffer_head.h:337 [inline]
 get_branch+0x2c3/0x6e0 fs/sysv/itree.c:101
 get_block+0x16c/0x1790 fs/sysv/itree.c:221
 block_read_full_page+0x2f9/0xde0 fs/buffer.c:2290
 do_read_cache_page+0x752/0x1040
 read_mapping_page include/linux/pagemap.h:515 [inline]
 dir_get_page fs/sysv/dir.c:58 [inline]
 sysv_readdir+0x19b/0x820 fs/sysv/dir.c:83
 iterate_dir+0x224/0x570
 __do_sys_getdents64 fs/readdir.c:369 [inline]
 __se_sys_getdents64+0x209/0x4f0 fs/readdir.c:354
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f82095c19f9
RSP: 002b:00007f8207a40048 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f820974ff80 RCX: 00007f82095c19f9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f820962f8ee R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f820974ff80 R15: 00007fff61b85888
 </TASK>
rcu: rcu_preempt kthread starved for 10529 jiffies! g82097 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:26816 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1f0 kernel/sched/core.c:6459
 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: 0 Comm: swapper/1 Not tainted 5.15.164-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
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_save_fl arch/x86/include/asm/irqflags.h:22 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:132 [inline]
RIP: 0010:acpi_safe_halt drivers/acpi/processor_idle.c:109 [inline]
RIP: 0010:acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:562
Code: ca 43 f7 48 83 e3 08 0f 85 0a 01 00 00 4c 8d 74 24 20 e8 c4 46 4a f7 0f 1f 44 00 00 e8 4a c6 43 f7 0f 00 2d c3 90 a6 00 fb f4 <4c> 89 f3 48 c1 eb 03 42 80 3c 3b 00 74 08 4c 89 f7 e8 8b 9a 8d f7
RSP: 0018:ffffc90000d67b00 EFLAGS: 000002d3
RAX: ffffffff8a3c9b16 RBX: 0000000000000000 RCX: ffff888012a10000
RDX: 0000000000000000 RSI: ffffffff8a8b2a00 RDI: ffffffff8ad8f800
RBP: ffffc90000d67b90 R08: ffffffff8186e200 R09: ffffed1002542001
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff920001acf60
R13: ffff888146226804 R14: ffffc90000d67b20 R15: dffffc0000000000
 acpi_idle_enter+0x352/0x4f0 drivers/acpi/processor_idle.c:697
 cpuidle_enter_state+0x521/0xef0 drivers/cpuidle/cpuidle.c:237
 cpuidle_enter+0x59/0x90 drivers/cpuidle/cpuidle.c:351
 call_cpuidle kernel/sched/idle.c:158 [inline]
 cpuidle_idle_call kernel/sched/idle.c:239 [inline]
 do_idle+0x3e4/0x670 kernel/sched/idle.c:306
 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:403
 start_secondary+0x371/0x500 arch/x86/kernel/smpboot.c:281
 secondary_startup_64_no_verify+0xb1/0xbb
 </TASK>