syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P7354/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=27089, q=342 ncpus=2)
task:udevd           state:R  running task     stack:24968 pid:7354  ppid:5136   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7009
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:mas_mn lib/maple_tree.c:313 [inline]
RIP: 0010:mas_next_node+0xf1/0xa10 lib/maple_tree.c:4546
Code: 25 7e fe ff 89 c5 31 ff 89 c6 e8 9a b5 2e f7 85 ed 0f 85 30 08 00 00 48 bd 00 00 00 00 00 fc ff df 48 8b 44 24 40 80 3c 28 00 <4c> 8b 74 24 28 74 08 4c 89 f7 e8 b0 1f 86 f7 4d 8b 3e 4d 89 fd 49
RSP: 0018:ffffc9000b8bf670 EFLAGS: 00000246
RAX: 1ffff92001717f07 RBX: ffffc9000b8bf820 RCX: 0000000000000000
RDX: ffff888027c38000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff2e5551c R12: 00007f0c17b37000
R13: ffff8880777dd800 R14: 0000000000000000 R15: dffffc0000000000
 mas_dfs_postorder lib/maple_tree.c:6701 [inline]
 mt_validate+0x310c/0x4530 lib/maple_tree.c:7235
 validate_mm+0xb1/0x420 mm/mmap.c:288
 vma_merge+0x1ab6/0x2110 mm/mmap.c:1035
 mprotect_fixup+0x47f/0xc90 mm/mprotect.c:632
 do_mprotect_pkey+0x76e/0xc30 mm/mprotect.c:819
 __do_sys_mprotect mm/mprotect.c:840 [inline]
 __se_sys_mprotect mm/mprotect.c:837 [inline]
 __x64_sys_mprotect+0x80/0x90 mm/mprotect.c:837
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f0c1751dfe7
RSP: 002b:00007ffc631bf548 EFLAGS: 00000246 ORIG_RAX: 000000000000000a
RAX: ffffffffffffffda RBX: 0000000000000200 RCX: 00007f0c1751dfe7
RDX: 0000000000000001 RSI: 0000000000000200 RDI: 00007f0c173ba000
RBP: 000055a71756f050 R08: 0000000000000000 R09: 0000000000000200
R10: 000055a71756f0b0 R11: 0000000000000246 R12: 0000000000000038
R13: 0000000000000400 R14: 000055a717570638 R15: 00007f0c17c0d39c
 </TASK>
rcu: rcu_preempt kthread starved for 10530 jiffies! g27089 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:27752 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </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: 0 Comm: swapper/1 Not tainted syzkaller #0
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:148
Code: cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d 23 bb 40 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 66 0f 1f 00 55 41 57 41 56
RSP: 0018:ffffc90000187de0 EFLAGS: 000002c2
RAX: de8f67998b20ed00 RBX: ffffffff8161881b RCX: de8f67998b20ed00
RDX: 0000000000000001 RSI: ffffffff8aaabce0 RDI: ffffffff8afc6f80
RBP: ffffc90000187f20 R08: ffff8880b8f36b2b R09: 1ffff110171e6d65
R10: dffffc0000000000 R11: ffffed10171e6d66 R12: ffffffff8e4a2128
R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff1100364e780
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000058 CR3: 000000005f253000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:753
 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97
 cpuidle_idle_call kernel/sched/idle.c:170 [inline]
 do_idle+0x1eb/0x510 kernel/sched/idle.c:282
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380
 start_secondary+0xee/0xf0 arch/x86/kernel/smpboot.c:323
 secondary_startup_64_no_verify+0x179/0x17b
 </TASK>