syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6521/1:b..l
	(detected by 0, t=10503 jiffies, g=25949, q=96 ncpus=2)
task:dhcpcd-run-hook state:R  running task     stack:24352 pid:6521  ppid:3933   flags:0x00004002
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:mas_validate_parent_slot lib/maple_tree.c:-1 [inline]
RIP: 0010:mt_validate+0xfbd/0x4c90 lib/maple_tree.c:7240
Code: e8 c8 92 64 f7 41 89 c4 31 ff 89 c6 e8 0c 62 7b f7 45 85 e4 0f 84 ae 00 00 00 e8 9e 5e 7b f7 48 89 df 4c 89 f6 e8 73 60 7b f7 <4c> 8b a4 24 38 01 00 00 49 39 de 75 5d 4d 39 e5 0f 85 bf 00 00 00
RSP: 0018:ffffc900034f75e0 EFLAGS: 00000293
RAX: ffffffff8a0577cd RBX: 0000000000000008 RCX: ffff88801dbe0000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000008
RBP: ffffc900034f77b0 R08: 0000000000000004 R09: 0000000000000003
R10: fffffbfff2e0b09c R11: 1ffffffff2e0b09c R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000000 R15: ffff888051d22e90
 validate_mm_mt+0xcd/0x420 mm/mmap.c:295
 validate_mm+0xcc/0x2b0 mm/mmap.c:332
 __vma_adjust+0x17e0/0x1c60 mm/mmap.c:879
 vma_adjust include/linux/mm.h:2810 [inline]
 __split_vma+0x3a7/0x500 mm/mmap.c:-1
 mprotect_fixup+0x597/0x7f0 mm/mprotect.c:623
 do_mprotect_pkey+0x754/0xa40 mm/mprotect.c:792
 __do_sys_mprotect mm/mprotect.c:819 [inline]
 __se_sys_mprotect mm/mprotect.c:816 [inline]
 __x64_sys_mprotect+0x7c/0x90 mm/mprotect.c:816
 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: 0033:0x7f50343842c7
RSP: 002b:00007ffe9ff264a8 EFLAGS: 00000206 ORIG_RAX: 000000000000000a
RAX: ffffffffffffffda RBX: 00007f50343600c0 RCX: 00007f50343842c7
RDX: 0000000000000001 RSI: 0000000000003000 RDI: 00007f503435c000
RBP: 00007ffe9ff26770 R08: 0000000000000000 R09: 00007f50342ddbf7
R10: 00007f50343600c0 R11: 0000000000000206 R12: 0000000000000008
R13: 0000007c21727320 R14: 0000000000000000 R15: 00007f5034398310
 </TASK>
rcu: rcu_preempt kthread starved for 10506 jiffies! g25949 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:27368 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:2167
 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 6524 Comm: syz.6.607 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__lock_acquire+0xe19/0x7c50 kernel/locking/lockdep.c:-1
Code: 00 00 48 89 d8 48 c1 e8 03 48 89 84 24 d8 00 00 00 42 80 3c 00 00 74 12 48 89 df e8 e1 f9 6d 00 49 b8 00 00 00 00 00 fc ff df <48> 89 9c 24 c0 00 00 00 4c 8b 2b 48 83 7c 24 60 00 75 31 48 c7 c0
RSP: 0000:ffffc900035a77c0 EFLAGS: 00000046
RAX: 1ffff110060aa15a RBX: ffff888030550ad0 RCX: ffffffff81630b36
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90ae2250
RBP: ffffc900035a7a10 R08: dffffc0000000000 R09: fffffbfff215c44b
R10: fffffbfff215c44b R11: 1ffffffff215c44a R12: ffff888030550000
R13: ffff888030550b04 R14: ffff888030550ae0 R15: ffff888030550000
FS:  0000555574ed0500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f31dff8 CR3: 000000005ec17000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
 _raw_spin_lock_irq+0x9f/0xe0 kernel/locking/spinlock.c:170
 spin_lock_irq include/linux/spinlock.h:376 [inline]
 get_signal+0x24a/0x1350 kernel/signal.c:2664
 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
 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:316
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0033:0x7fde3666ef8d
Code: 14 d2 49 39 50 28 0f 82 b5 03 00 00 c6 44 24 1e 01 45 31 ff 45 31 f6 44 0f b6 e6 85 c0 0f 84 9e 00 00 00 44 89 f9 49 8b 50 40 <4c> 89 f0 49 03 14 ca 80 3d 0d 8e 37 00 00 49 89 d6 48 89 d5 74 28
RSP: 002b:00007ffe8a4f2240 EFLAGS: 00000297
RAX: 0000000000000001 RBX: 00007fde37515720 RCX: 0000000000034126
RDX: 0000000000000000 RSI: ffffffff8a07c7b9 RDI: 0000000000000012
RBP: ffffffff8a07c7b9 R08: 00007fde369e6218 R09: 00007fde369d2000
R10: 00007fde359fb008 R11: 0000000000000012 R12: 0000000000000012
R13: 0000000000000000 R14: ffffffff8a07c0fc R15: 0000000000034126
 </TASK>
sched: RT throttling activated