syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P9659/1:b..l P9676/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=32061, q=237 ncpus=2)
task:dhcpcd-run-hook state:R  running task     stack:26776 pid:9676  tgid:9676  ppid:5478   task_flags:0x400000 flags:0x00080001
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x1139/0x6150 kernel/sched/core.c:6863
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7190
 irqentry_exit+0x1d8/0x8c0 kernel/entry/common.c:216
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_acquire+0x79/0x330 kernel/locking/lockdep.c:5872
Code: 82 74 02 00 00 8b 35 ba eb ee 0e 85 f6 0f 85 8d 00 00 00 48 8b 44 24 30 65 48 2b 05 39 b4 18 12 0f 85 ad 02 00 00 48 83 c4 38 <5b> 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 65 8b 05 45 b4 18 12
RSP: 0018:ffffc90003437298 EFLAGS: 00000282
RAX: 0000000000000000 RBX: ffffffff8e3c96a0 RCX: 0000000013d622c6
RDX: 0000000000000000 RSI: ffffffff8daa7ee5 RDI: ffffffff8bf2b400
RBP: 0000000000000002 R08: 00000000accd7842 R09: 000000002accd784
R10: 0000000000000002 R11: ffff88802e178b30 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 rcu_read_lock include/linux/rcupdate.h:867 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1195 [inline]
 unwind_next_frame+0xd1/0x20b0 arch/x86/kernel/unwind_orc.c:495
 arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 kmem_cache_alloc_noprof+0x25e/0x770 mm/slub.c:5270
 ptlock_alloc+0x1f/0x70 mm/memory.c:7377
 ptlock_init include/linux/mm.h:3280 [inline]
 pagetable_pte_ctor include/linux/mm.h:3334 [inline]
 __pte_alloc_one_noprof include/asm-generic/pgalloc.h:79 [inline]
 pte_alloc_one+0x84/0x3d0 arch/x86/mm/pgtable.c:18
 __do_fault+0x320/0x490 mm/memory.c:5315
 do_cow_fault mm/memory.c:5785 [inline]
 do_fault+0x111c/0x1ad0 mm/memory.c:5891
 do_pte_missing mm/memory.c:4401 [inline]
 handle_pte_fault mm/memory.c:6273 [inline]
 __handle_mm_fault+0x1919/0x2bb0 mm/memory.c:6411
 handle_mm_fault+0x3fe/0xad0 mm/memory.c:6580
 do_user_addr_fault+0x7a6/0x1370 arch/x86/mm/fault.c:1387
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x64/0xc0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0010:rep_stos_alternative+0x40/0x80 arch/x86/lib/clear_page_64.S:99
Code: c9 75 f6 c3 cc cc cc cc 48 89 07 48 83 c7 08 83 e9 08 74 ef 83 f9 08 73 ef eb de 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 <48> 89 07 48 89 47 08 48 89 47 10 48 89 47 18 48 89 47 20 48 89 47
RSP: 0018:ffffc90003437b98 EFLAGS: 00050206
RAX: 0000000000000000 RBX: ffff8880491f9118 RCX: 0000000000000ff8
RDX: ffff88802e178000 RSI: ffffffff825d389e RDI: 0000562678428008
RBP: 0000562678427000 R08: 00000000ffffffff R09: 00000000ffffffff
R10: 0000000000000001 R11: ffff88802e178b30 R12: 0000562678428010
R13: 0000000000000008 R14: ffff8880491f9138 R15: 00007ffffffff000
 __clear_user arch/x86/include/asm/uaccess_64.h:188 [inline]
 clear_user arch/x86/include/asm/uaccess_64.h:205 [inline]
 padzero fs/binfmt_elf.c:133 [inline]
 elf_load+0x5f5/0x780 fs/binfmt_elf.c:435
 load_elf_binary+0x1422/0x4fe0 fs/binfmt_elf.c:1188
 search_binary_handler fs/exec.c:1669 [inline]
 exec_binprm fs/exec.c:1701 [inline]
 bprm_execve fs/exec.c:1753 [inline]
 bprm_execve+0x8c2/0x1620 fs/exec.c:1729
 do_execveat_common.isra.0+0x4a5/0x610 fs/exec.c:1859
 do_execve fs/exec.c:1933 [inline]
 __do_sys_execve fs/exec.c:2009 [inline]
 __se_sys_execve fs/exec.c:2004 [inline]
 __x64_sys_execve+0x8e/0xb0 fs/exec.c:2004
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbe3fd72107
RSP: 002b:00007fbe3fbdbe68 EFLAGS: 00000202 ORIG_RAX: 000000000000003b
RAX: ffffffffffffffda RBX: 00007ffd4315bf10 RCX: 00007fbe3fd72107
RDX: 0000555afe4494c0 RSI: 00007ffd4315c100 RDI: 0000555af56f36bd
RBP: 00007fbe3fbdbff0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000008 R11: 0000000000000202 R12: 0000000000000001
R13: 00007ffd4315bbf0 R14: 00007fbe3fbdbf20 R15: 0000000000000040
 </TASK>
task:syz.2.911       state:R  running task     stack:26888 pid:9659  tgid:9658  ppid:5813   task_flags:0x40044c flags:0x00080001
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x1139/0x6150 kernel/sched/core.c:6863
 preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:7047
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 zap_pte_range mm/memory.c:1884 [inline]
 zap_pmd_range mm/memory.c:1946 [inline]
 zap_pud_range mm/memory.c:1975 [inline]
 zap_p4d_range mm/memory.c:1996 [inline]
 unmap_page_range+0x1047/0x43c0 mm/memory.c:2017
 unmap_single_vma+0x153/0x240 mm/memory.c:2059
 unmap_vmas+0x218/0x470 mm/memory.c:2101
 exit_mmap+0x1b0/0xb60 mm/mmap.c:1277
 __mmput+0x12a/0x410 kernel/fork.c:1173
 mmput+0x62/0x70 kernel/fork.c:1196
 exit_mm kernel/exit.c:581 [inline]
 do_exit+0x7d7/0x2bd0 kernel/exit.c:959
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1112
 get_signal+0x2671/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7e0 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
 exit_to_user_mode_loop+0x8c/0x540 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x4ee/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f658518f749
RSP: 002b:00007f65860fa038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: 0000000000000001 RBX: 00007f65853e5fa0 RCX: 00007f658518f749
RDX: 0000000000000001 RSI: 0000200000000700 RDI: 0000000000000003
RBP: 00007f6585213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f65853e6038 R14: 00007f65853e5fa0 R15: 00007ffdbc14c1d8
 </TASK>
rcu: rcu_preempt kthread starved for 10583 jiffies! g32061 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:28408 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x1139/0x6150 kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6960
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x983/0xb10 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:
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 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+0xf/0x20 arch/x86/kernel/paravirt.c:82
Code: c6 5f 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 13 49 12 00 fb f4 <e9> cc 35 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffffff8e007df8 EFLAGS: 000002c6
RAX: 0000000000f1a033 RBX: 0000000000000000 RCX: ffffffff8b7816d9
RDX: 0000000000000000 RSI: ffffffff8dacdf79 RDI: ffffffff8bf2b400
RBP: fffffbfff1c12f68 R08: 0000000000000001 R09: ffffed101708673d
R10: ffff8880b84339eb R11: ffffffff8e098670 R12: 0000000000000000
R13: ffffffff8e097b40 R14: ffffffff9088b6d0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881248f5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c36117e CR3: 000000003529b000 CR4: 00000000003526f0
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+0x6c/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x38d/0x510 kernel/sched/idle.c:332
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:430
 rest_init+0x16b/0x2b0 init/main.c:757
 start_kernel+0x3ef/0x4d0 init/main.c:1206
 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:310
 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:291
 common_startup_64+0x13e/0x148
 </TASK>