syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6717/1:b..l
	(detected by 0, t=10502 jiffies, g=25573, q=289 ncpus=2)
task:dhcpcd-run-hook state:R  running task     stack:24336 pid:6717  ppid:3933   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6874
 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:check_kcov_mode kernel/kcov.c:184 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:245 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x2c/0x80 kernel/kcov.c:313
Code: 04 24 65 48 8b 15 24 f8 7f 7e 65 8b 0d 25 f8 7f 7e 81 e1 00 01 ff 00 74 11 81 f9 00 01 00 00 75 5b 83 ba 1c 16 00 00 00 74 52 <8b> 8a f8 15 00 00 83 f9 03 75 47 48 8b 8a 00 16 00 00 44 8b 8a fc
RSP: 0018:ffffc900038f75f8 EFLAGS: 00000246
RAX: ffffffff8a1a3684 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff8880283c5940 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900038f77b0 R08: ffff8880283c5940 R09: 0000000000000003
R10: 0000000000000003 R11: 0000000000000000 R12: ffff88807d7b40d8
R13: ffff88807d1e6e80 R14: ffff88801ce7e900 R15: 0000000000000001
 mt_slot lib/maple_tree.c:816 [inline]
 mas_slot lib/maple_tree.c:849 [inline]
 mt_validate_nulls lib/maple_tree.c:7193 [inline]
 mt_validate+0x4344/0x4cb0 lib/maple_tree.c:7249
 validate_mm_mt+0xe2/0x440 mm/mmap.c:295
 validate_mm+0xe1/0x2e0 mm/mmap.c:332
 __vma_adjust+0x1855/0x1cd0 mm/mmap.c:879
 vma_adjust include/linux/mm.h:2810 [inline]
 __split_vma+0x3a7/0x500 mm/mmap.c:-1
 mprotect_fixup+0x5b1/0x800 mm/mprotect.c:623
 do_mprotect_pkey+0x7fe/0xba0 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:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f7647f9d2c7
RSP: 002b:00007ffef17ce0e8 EFLAGS: 00000206 ORIG_RAX: 000000000000000a
RAX: ffffffffffffffda RBX: 00007f7647f7a050 RCX: 00007f7647f9d2c7
RDX: 0000000000000001 RSI: 0000000000001000 RDI: 00007f7647cc4000
RBP: 00007ffef17ce3b0 R08: 0000000000000000 R09: 00007f7647d16870
R10: 00007f7647f7a050 R11: 0000000000000206 R12: 0000000000000010
R13: 000000af43eef80f R14: 0000000000000000 R15: 00007f7647fb1310
 </TASK>
rcu: rcu_preempt kthread starved for 7776 jiffies! g25573 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:27760 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x99/0x3b0 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:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:742
Code: 48 89 df e8 b7 d1 9c f7 e9 44 ff ff ff e8 3d 07 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 66 90 0f 00 2d 77 1c 50 00 fb f4 <c3> 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48
RSP: 0018:ffffffff8c807d88 EFLAGS: 000002c6
RAX: ef8bed2ee720fd00 RBX: ffffffff8a3692b7 RCX: ef8bed2ee720fd00
RDX: 0000000000000001 RSI: ffffffff8a8c1220 RDI: ffffffff8adf0d20
RBP: ffffffff8c807ec0 R08: ffff8880b8e3580b R09: 1ffff110171c6b01
R10: dffffc0000000000 R11: ffffed10171c6b02 R12: 1ffffffff1900fbc
R13: dffffc0000000000 R14: ffffffff8c8bc740 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f227808ff46 CR3: 0000000074091000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 default_idle_call+0x84/0xc0 kernel/sched/idle.c:109
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x20d/0x5a0 kernel/sched/idle.c:303
 cpu_startup_entry+0x3f/0x60 kernel/sched/idle.c:401
 rest_init+0x2dc/0x300 init/main.c:745
 arch_call_rest_init+0xa/0xa init/main.c:905
 start_kernel+0x493/0x53c init/main.c:1152
 secondary_startup_64_no_verify+0xcf/0xdb
 </TASK>