syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P15233/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=75149, q=525 ncpus=2)
task:syz.1.2437      state:R  running task     stack:25688 pid:15233 tgid:15232 ppid:5832   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x14bc/0x5000 kernel/sched/core.c:6863
 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7190
 irqentry_exit+0x5d8/0x660 kernel/entry/common.c:216
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:__asan_memset+0x31/0x50 mm/kasan/shadow.c:87
Code: 53 48 89 d3 89 f5 49 89 fe 48 8b 4c 24 18 48 89 d6 ba 01 00 00 00 e8 7e e4 ff ff 84 c0 74 11 4c 89 f7 89 ee 48 89 da 5b 41 5e <5d> e9 e9 4b 27 09 31 c0 5b 41 5e 5d e9 f9 93 e8 fe cc 66 66 66 66
RSP: 0018:ffffc90002fc7028 EFLAGS: 00000202
RAX: 1ffff920005f8e01 RBX: ffffc90002fc7140 RCX: ffffffff81740b38
RDX: 0000000000000010 RSI: 0000000000000000 RDI: ffffc90002fc7158
RBP: 0000000000000000 R08: ffffc90002fc7167 R09: 1ffff920005f8e2c
R10: dffffc0000000000 R11: fffff520005f8e2d R12: ffffc90002fc7f48
R13: ffffc90002fc7158 R14: ffffc90002fc7108 R15: ffffc90002fc7150
 unwind_next_frame+0xc98/0x2390 arch/x86/kernel/unwind_orc.c:592
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 save_stack+0xf5/0x1f0 mm/page_owner.c:165
 __set_page_owner+0x8d/0x4c0 mm/page_owner.c:341
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x234/0x290 mm/page_alloc.c:1846
 prep_new_page mm/page_alloc.c:1854 [inline]
 get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3915
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5210
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
 folio_alloc_mpol_noprof+0x39/0x70 mm/mempolicy.c:2505
 shmem_alloc_folio mm/shmem.c:1888 [inline]
 shmem_alloc_and_add_folio+0x423/0xf40 mm/shmem.c:1930
 shmem_get_folio_gfp+0x59d/0x1660 mm/shmem.c:2554
 shmem_get_folio mm/shmem.c:2660 [inline]
 shmem_write_begin+0xf7/0x2b0 mm/shmem.c:3309
 generic_perform_write+0x2c5/0x900 mm/filemap.c:4314
 shmem_file_write_iter+0xf8/0x120 mm/shmem.c:3484
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x5c9/0xb30 fs/read_write.c:686
 ksys_write+0x145/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f78d278e1ff
RSP: 002b:00007f78d3619df0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000001000000 RCX: 00007f78d278e1ff
RDX: 0000000001000000 RSI: 00007f78c8400000 RDI: 0000000000000009
RBP: 0000000000000000 R08: 0000000000000000 R09: 00000000000055a8
R10: 0000000000000002 R11: 0000000000000293 R12: 0000000000000009
R13: 00007f78d3619ef0 R14: 00007f78d3619eb0 R15: 00007f78c8400000
 </TASK>
rcu: rcu_preempt kthread starved for 10558 jiffies! g75149 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:27200 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x14bc/0x5000 kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6960
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82
Code: ce 73 c1 f5 cc cc cc 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 83 80 19 00 f3 0f 1e fa fb f4 <e9> a3 73 c1 f5 cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90000197de0 EFLAGS: 000002c6
RAX: 4cfe6d7a5c581500 RBX: ffffffff81974b6a RCX: 4cfe6d7a5c581500
RDX: 0000000000000001 RSI: ffffffff8d7831da RDI: ffffffff8bc00c60
RBP: ffffc90000197f10 R08: ffff8880b89336db R09: 1ffff110171266db
R10: dffffc0000000000 R11: ffffed10171266dc R12: ffffffff8f815070
R13: 1ffff11003956b70 R14: 0000000000000001 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff888126184000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe29577e000 CR3: 000000005b6f5000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:767
 default_idle_call+0x73/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x1ea/0x520 kernel/sched/idle.c:332
 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:430
 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312
 common_startup_64+0x13e/0x147
 </TASK>