syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4270/1:b..l
	(detected by 0, t=10502 jiffies, g=14293, q=164 ncpus=2)
task:syz-executor    state:R  running task     stack:22000 pid:4270  ppid:4264   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6874
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:unwind_next_frame+0x75/0x20b0 arch/x86/kernel/unwind_orc.c:425
Code: 03 48 89 44 24 50 42 80 3c 30 00 74 08 4c 89 ff e8 b0 47 9a 00 4c 89 7c 24 58 4c 8b 6b 38 49 89 df 49 c1 ef 03 43 0f b6 04 37 <84> c0 0f 85 a0 19 00 00 8b 03 85 c0 0f 84 79 18 00 00 48 89 6c 24
RSP: 0018:ffffc90004207330 EFLAGS: 00000a06
RAX: 0000000000000000 RBX: ffffc90004207408 RCX: 0000000080000000
RDX: dffffc0000000000 RSI: ffffffff81b16aa6 RDI: ffffc90004207408
RBP: ffffc90004207450 R08: ffffc900042074d0 R09: 0000000000000002
R10: dffffc0000000000 R11: fffff52000840e8d R12: ffffffff81b16aa6
R13: ffffc900042077c0 R14: dffffc0000000000 R15: 1ffff92000840e81
 arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 save_stack+0x121/0x230 mm/page_owner.c:127
 __reset_page_owner+0x51/0x1a0 mm/page_owner.c:148
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1486 [inline]
 free_pcp_prepare mm/page_alloc.c:1536 [inline]
 free_unref_page_prepare+0x8b4/0x9a0 mm/page_alloc.c:3413
 free_unref_page_list+0xbb/0x8e0 mm/page_alloc.c:3554
 release_pages+0x1fa6/0x2220 mm/swap.c:1035
 __pagevec_release+0x6d/0xe0 mm/swap.c:1055
 pagevec_release include/linux/pagevec.h:71 [inline]
 folio_batch_release include/linux/pagevec.h:135 [inline]
 shmem_undo_range+0x7c2/0x20c0 mm/shmem.c:946
 shmem_truncate_range mm/shmem.c:1062 [inline]
 shmem_evict_inode+0x25b/0xa80 mm/shmem.c:1171
 evict+0x4c9/0x8d0 fs/inode.c:705
 do_unlinkat+0x388/0x580 fs/namei.c:4405
 __do_sys_unlink fs/namei.c:4446 [inline]
 __se_sys_unlink fs/namei.c:4444 [inline]
 __x64_sys_unlink+0x45/0x50 fs/namei.c:4444
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fcf72f9b717
RSP: 002b:00007ffe20ebada8 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fcf72f9b717
RDX: 00007ffe20ebadd0 RSI: 00007ffe20ebae60 RDI: 00007ffe20ebae60
RBP: 00007ffe20ebae60 R08: 00007ffe20ebbe60 R09: 00000000ffffffff
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffe20ebbef0
R13: 00007fcf73031ef0 R14: 0000000000026005 R15: 00007ffe20ebbf30
 </TASK>
rcu: rcu_preempt kthread starved for 9496 jiffies! g14293 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:27256 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:742
Code: 48 89 df e8 27 c3 9c f7 e9 44 ff ff ff e8 3d 07 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 66 90 0f 00 2d 77 0c 50 00 fb f4 <c3> 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48
RSP: 0018:ffffffff8c807d88 EFLAGS: 000002c6
RAX: 64dbadd9a31c7700 RBX: ffffffff8a36a2b7 RCX: 64dbadd9a31c7700
RDX: 0000000000000001 RSI: ffffffff8a8c1220 RDI: ffffffff8adf0de0
RBP: ffffffff8c807ec0 R08: ffff8880b8e3580b R09: 1ffff110171c6b01
R10: dffffc0000000000 R11: ffffed10171c6b02 R12: 1ffffffff1900fbc
R13: dffffc0000000000 R14: ffffffff8c8bc740 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe61c9e56dc CR3: 000000002f1dd000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 default_idle_call+0x84/0xc0 kernel/sched/idle.c:109
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x20d/0x5a0 kernel/sched/idle.c:303
 cpu_startup_entry+0x3f/0x60 kernel/sched/idle.c:401
 rest_init+0x2dc/0x300 init/main.c:745
 arch_call_rest_init+0xa/0xa init/main.c:905
 start_kernel+0x493/0x53c init/main.c:1152
 secondary_startup_64_no_verify+0xcf/0xdb
 </TASK>