syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10504 jiffies, g=12125, q=582 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 6246 (4294975265-4294969019), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 6246 jiffies! g12125 f0x2 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:25784 pid:18    tgid:18    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5378 [inline]
 __schedule+0x190e/0x4c90 kernel/sched/core.c:6765
 __schedule_loop kernel/sched/core.c:6842 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6857
 schedule_timeout+0x15a/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x2df/0x1330 kernel/rcu/tree.c:2024
 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2226
 kthread+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </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: 6058 Comm: dhcpcd Not tainted 6.14.0-rc7-syzkaller-00196-g88d324e69ea9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:advance_sched+0x602/0xca0
Code: 23 f8 48 8b 1b 42 80 7c 25 00 00 48 8b 6c 24 40 74 08 4c 89 ef e8 3e e9 23 f8 4b 03 1c fe 48 89 e8 48 c1 e8 03 42 80 3c 20 00 <74> 08 48 89 ef e8 14 ea 23 f8 4b 89 9c fe c0 00 00 00 4c 39 bc 24
RSP: 0018:ffffc90000a28c70 EFLAGS: 00000046
RAX: 1ffff1100ee54f99 RBX: 0000005414fd3780 RCX: ffff88802ea4bc00
RDX: 0000000000010000 RSI: 0000000000000cb2 RDI: 0000000000000000
RBP: ffff8880772a7cc8 R08: ffffffff8a0535b3 R09: fffff5200014517c
R10: dffffc0000000000 R11: fffff5200014517c R12: dffffc0000000000
R13: ffff8880772a7c08 R14: ffff8880772a7c00 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f530816680 CR3: 0000000030c94000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <IRQ>
 __run_hrtimer kernel/time/hrtimer.c:1801 [inline]
 __hrtimer_run_queues+0x59b/0xd30 kernel/time/hrtimer.c:1865
 hrtimer_interrupt+0x403/0xa40 kernel/time/hrtimer.c:1927
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
 __sysvec_apic_timer_interrupt+0x110/0x420 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1049
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire+0x26/0x550 kernel/locking/lockdep.c:5819
Code: 90 90 90 90 f3 0f 1e fa 55 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec 20 01 00 00 4c 89 4c 24 28 4c 89 44 24 38 <48> 89 4c 24 30 89 54 24 1c 41 89 f6 48 89 7c 24 20 65 48 8b 04 25
RSP: 0018:ffffc90003477300 EFLAGS: 00000286
RAX: 0000000000000002 RBX: 00000000000001e0 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8eb39360
RBP: ffffc90003477450 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff940003ff849 R12: dffffc0000000000
R13: 000000000007ff09 R14: ffffffff823510f6 R15: ffff88813fffa720
 rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 rcu_read_lock_sched include/linux/rcupdate.h:941 [inline]
 pfn_valid+0x113/0x450 include/linux/mmzone.h:2067
 page_table_check_clear+0x1e/0x550 mm/page_table_check.c:70
 get_and_clear_full_ptes include/linux/pgtable.h:712 [inline]
 zap_present_folio_ptes mm/memory.c:1510 [inline]
 zap_present_ptes mm/memory.c:1595 [inline]
 do_zap_pte_range mm/memory.c:1697 [inline]
 zap_pte_range mm/memory.c:1741 [inline]
 zap_pmd_range mm/memory.c:1833 [inline]
 zap_pud_range mm/memory.c:1862 [inline]
 zap_p4d_range mm/memory.c:1883 [inline]
 unmap_page_range+0x33fa/0x4510 mm/memory.c:1904
 unmap_vmas+0x3cc/0x5f0 mm/memory.c:1994
 exit_mmap+0x283/0xd40 mm/mmap.c:1284
 __mmput+0x115/0x420 kernel/fork.c:1356
 exit_mm+0x220/0x310 kernel/exit.c:570
 do_exit+0x9ad/0x2940 kernel/exit.c:925
 do_group_exit+0x207/0x2c0 kernel/exit.c:1087
 __do_sys_exit_group kernel/exit.c:1098 [inline]
 __se_sys_exit_group kernel/exit.c:1096 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1096
 x64_sys_call+0x26a8/0x26b0 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f607778da90
Code: Unable to access opcode bytes at 0x7f607778da66.
RSP: 002b:00007fff567133d8 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f60776dd6c0 RCX: 00007f607778da90
RDX: 00000000000000e7 RSI: 000000000000003c RDI: 0000000000000001
RBP: 00007fff56713458 R08: 0000000000000007 R09: 6c68308a5d4c873d
R10: 0000000000000770 R11: 0000000000000202 R12: 0000000000000001
R13: 00007fff56713a28 R14: 0000000000000003 R15: 0000000000000000
 </TASK>