syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5104/1:b..l
	(detected by 0, t=10502 jiffies, g=11465, q=212 ncpus=2)
task:modprobe        state:R  running task     stack:24032 pid:5104  ppid:4618   flags:0x00004000
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:__sanitizer_cov_trace_switch+0x3f/0xe0 kernel/kcov.c:-1
Code: 00 b8 8b 00 00 00 0f a3 c8 0f 83 b3 00 00 00 48 8b 06 48 85 c0 0f 84 a7 00 00 00 41 57 41 56 41 54 53 48 8b 0c cd 18 1a 90 8a <48> 8b 54 24 20 65 4c 8b 05 34 94 81 7e 45 31 c9 eb 08 49 ff c1 4c
RSP: 0018:ffffc9000cadf398 EFLAGS: 00000206
RAX: 0000000000000003 RBX: dffffc0000000000 RCX: 0000000000000005
RDX: 0000000000000001 RSI: ffffffff8e0853a0 RDI: 0000000000000001
RBP: ffffc9000cadf590 R08: 0000000000000004 R09: 0000000000000003
R10: fffffbfff2e0b09c R11: 1ffffffff2e0b09c R12: ffff88802f7e5b60
R13: ffff888028888680 R14: ffff888028888600 R15: 0000000000000001
 mas_data_end lib/maple_tree.c:1483 [inline]
 mt_validate_nulls lib/maple_tree.c:7198 [inline]
 mt_validate+0x4478/0x4c90 lib/maple_tree.c:7247
 validate_mm_mt+0xcd/0x420 mm/mmap.c:295
 validate_mm+0xcc/0x2b0 mm/mmap.c:332
 remove_mt mm/mmap.c:2322 [inline]
 do_mas_align_munmap+0xf98/0x1220 mm/mmap.c:2595
 do_mas_munmap+0x240/0x2b0 mm/mmap.c:2650
 __mmap_region mm/mmap.c:2698 [inline]
 mmap_region+0x6e5/0x1c70 mm/mmap.c:2916
 do_mmap+0x958/0xfd0 mm/mmap.c:1436
 vm_mmap_pgoff+0x1b2/0x2b0 mm/util.c:520
 ksys_mmap_pgoff+0x516/0x6f0 mm/mmap.c:1482
 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: 0033:0x7f909f4dc242
RSP: 002b:00007ffdb743c708 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f909f23e000 RCX: 00007f909f4dc242
RDX: 0000000000000005 RSI: 000000000014e000 RDI: 00007f909f23e000
RBP: 0000000000000812 R08: 0000000000000000 R09: 0000000000028000
R10: 0000000000000812 R11: 0000000000000206 R12: 00007ffdb743c758
R13: 00007f909f4b85f0 R14: 00007ffdb743cf40 R15: 00000fffb6e878e4
 </TASK>
rcu: rcu_preempt kthread starved for 9756 jiffies! g11465 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:26880 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:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:742
Code: 48 89 df e8 b7 3b af f7 e9 4c ff ff ff e8 dd 07 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 66 90 0f 00 2d 97 d4 64 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: 6580d828492cd100 RBX: ffffffff8a21ce97 RCX: 6580d828492cd100
RDX: 0000000000000001 RSI: ffffffff8a8c0580 RDI: ffffffff8adef760
RBP: ffffffff8c807ec0 R08: dffffc0000000000 R09: ffffed10171c6afa
R10: ffffed10171c6afa R11: 1ffff110171c6af9 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8c8bc740 R15: 1ffffffff1c3ed96
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8795e9e269 CR3: 000000001c6ed000 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+0x1fc/0x570 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+0x490/0x539 init/main.c:1152
 secondary_startup_64_no_verify+0xcf/0xdb
 </TASK>