syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P7671/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=15177, q=1031 ncpus=2)
task:syz.0.390       state:R  running task     stack:26400 pid:7671  tgid:7659  ppid:5821   task_flags:0x400140 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x116f/0x5de0 kernel/sched/core.c:6767
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7090
 irqentry_exit+0x36/0x90 kernel/entry/common.c:354
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire+0x62/0x350 kernel/locking/lockdep.c:5870
Code: b1 0e 12 83 f8 07 0f 87 bc 02 00 00 89 c0 48 0f a3 05 22 34 ee 0e 0f 82 74 02 00 00 8b 35 9a 63 ee 0e 85 f6 0f 85 8d 00 00 00 <48> 8b 44 24 30 65 48 2b 05 f9 b0 0e 12 0f 85 c7 02 00 00 48 83 c4
RSP: 0018:ffffc9001bc9f1b0 EFLAGS: 00000206
RAX: 0000000000000046 RBX: ffffffff8e3c1580 RCX: 00000000a07923a3
RDX: 0000000000000000 RSI: ffffffff8dbc95df RDI: ffffffff8bf46580
RBP: 0000000000000002 R08: 22dd6caee5500fac R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 rcu_read_lock include/linux/rcupdate.h:841 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1155 [inline]
 unwind_next_frame+0xd1/0x20a0 arch/x86/kernel/unwind_orc.c:479
 arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 save_stack+0x160/0x1f0 mm/page_owner.c:156
 __reset_page_owner+0x84/0x1a0 mm/page_owner.c:308
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1262 [inline]
 free_unref_folios+0x999/0x1630 mm/page_alloc.c:2737
 folios_put_refs+0x56f/0x740 mm/swap.c:992
 folio_batch_release include/linux/pagevec.h:101 [inline]
 mapping_try_invalidate+0x2fd/0x3c0 mm/truncate.c:550
 drop_pagecache_sb+0xe2/0x2a0 fs/drop_caches.c:40
 iterate_supers+0xfb/0x240 fs/super.c:934
 drop_caches_sysctl_handler fs/drop_caches.c:64 [inline]
 drop_caches_sysctl_handler+0xeb/0x190 fs/drop_caches.c:51
 proc_sys_call_handler+0x3bf/0x5c0 fs/proc/proc_sysctl.c:601
 do_iter_readv_writev+0x654/0x950 fs/read_write.c:825
 vfs_writev+0x353/0xdc0 fs/read_write.c:1055
 do_writev+0x132/0x330 fs/read_write.c:1101
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc94df8d169
RSP: 002b:00007fc94ee72038 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007fc94e1a6080 RCX: 00007fc94df8d169
RDX: 0000000000000002 RSI: 0000200000000080 RDI: 0000000000000005
RBP: 00007fc94e00e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fc94e1a6080 R15: 00007ffc858c1718
 </TASK>
rcu: rcu_preempt kthread starved for 10547 jiffies! g15177 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:27704 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x116f/0x5de0 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6860
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2046
 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2248
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.14.0-syzkaller-13423-ga8662bcd2ff1 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:81
Code: 95 5d 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d d3 bc 17 00 fb f4 <c3> cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffffff8e007e10 EFLAGS: 000002c6
RAX: 0000000000d737e3 RBX: 0000000000000000 RCX: ffffffff8b723439
RDX: 0000000000000000 RSI: ffffffff8dbeeb53 RDI: ffffffff8bf46580
RBP: fffffbfff1c12ee8 R08: 0000000000000001 R09: ffffed10170865bd
R10: ffff8880b8432deb R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff8e097740 R14: ffffffff90865310 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881249b3000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055694d7ef060 CR3: 000000002a0ae000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:748
 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:117
 cpuidle_idle_call kernel/sched/idle.c:185 [inline]
 do_idle+0x391/0x510 kernel/sched/idle.c:325
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:423
 rest_init+0x16b/0x2b0 init/main.c:743
 start_kernel+0x3e9/0x4d0 init/main.c:1099
 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:513
 x86_64_start_kernel+0xb0/0xc0 arch/x86/kernel/head64.c:494
 common_startup_64+0x13e/0x148
 </TASK>