syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4274/1:b..l
	(detected by 1, t=10502 jiffies, g=33393, q=46 ncpus=2)
task:syz-executor    state:R  running task     stack:22656 pid:4274  ppid:4260   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 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:lock_acquire+0x20f/0x490 kernel/locking/lockdep.c:5666
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0018:ffffc90003e57520 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 6dca5cc65b218500
RDX: 0000000000000000 RSI: ffffffff8a6c1780 RDI: ffffffff8abef920
RBP: ffffc90003e57640 R08: dffffc0000000000 R09: fffffbfff2119049
R10: fffffbfff2119049 R11: 1ffffffff2119048 R12: 0000000000000001
R13: 1ffff920007caeb0 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 page_ext_get+0x3a/0x2a0 mm/page_ext.c:157
 __reset_page_owner+0x31/0x1a0 mm/page_owner.c:144
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1459 [inline]
 free_pcp_prepare mm/page_alloc.c:1509 [inline]
 free_unref_page_prepare+0x8b4/0x9a0 mm/page_alloc.c:3384
 free_unref_page_list+0xbb/0x8e0 mm/page_alloc.c:3525
 release_pages+0x1f92/0x2200 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+0x75b/0x2050 mm/shmem.c:946
 shmem_truncate_range mm/shmem.c:1062 [inline]
 shmem_evict_inode+0x248/0xa40 mm/shmem.c:1171
 evict+0x485/0x870 fs/inode.c:705
 do_unlinkat+0x377/0x560 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:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6f25f8ecf7
RSP: 002b:00007ffc42773978 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f6f25f8ecf7
RDX: 00007ffc427739a0 RSI: 00007ffc42773a30 RDI: 00007ffc42773a30
RBP: 00007ffc42773a30 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffc42774ac0
R13: 00007f6f26013d7d R14: 000000000004ef4f R15: 00007ffc42774b00
 </TASK>
rcu: rcu_preempt kthread starved for 10409 jiffies! g33393 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:27576 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 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:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 7027 Comm: syz.4.578 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:101 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x5c/0x290 mm/kasan/generic.c:189
Code: 01 00 00 00 00 fc ff df 49 89 fb 49 c1 eb 03 49 b8 00 00 00 00 00 fc ff df 4f 8d 0c 03 48 8d 5c 37 ff 48 c1 eb 03 4e 8d 14 3b <4d> 89 d6 4d 29 ce 49 83 fe 10 7f 26 4d 85 f6 0f 84 39 01 00 00 48
RSP: 0018:ffffc900035576e0 EFLAGS: 00000807
RAX: 0000000000000001 RBX: 1ffffffff2119048 RCX: ffffffff81631a45
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff908c8240
RBP: ffffc90003557950 R08: dffffc0000000000 R09: fffffbfff2119048
R10: fffffbfff2119049 R11: 1ffffffff2119048 R12: 00000000da2e6163
R13: 000000000000402d R14: 0000000034457c0f R15: dffffc0000000001
FS:  000055557a516500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2e5dbeaf98 CR3: 0000000056805000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 instrument_atomic_read include/linux/instrumented.h:72 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 hlock_class kernel/locking/lockdep.c:228 [inline]
 __lock_acquire+0x12e5/0x7c50 kernel/locking/lockdep.c:5046
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 __lock_timer+0x55/0x3f0 kernel/time/posix-timers.c:631
 posixtimer_rearm+0x5c/0x340 kernel/time/posix-timers.c:324
 dequeue_signal+0x1b6/0x4b0 kernel/signal.c:704
 get_signal+0x547/0x1350 kernel/signal.c:2751
 arch_do_signal_or_restart+0xb7/0x1240 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f2e5cd8f751
Code: 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 48 3d 01 f0 ff ff 73 01 <c3> 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f
RSP: 002b:00007ffe270b4758 EFLAGS: 00000217
RAX: 0000000000000000 RBX: 000000000004f834 RCX: 00007f2e5cd8f749
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f2e5cfe609c
RBP: 0000000000000032 R08: 00280cb6eec6ea32 R09: 00000019270b4a4f
R10: 00007ffe270b4850 R11: 0000000000000246 R12: 00007f2e5cfe609c
R13: 00007ffe270b4850 R14: 000000000004f866 R15: 00007ffe270b4870
 </TASK>