syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4383/1:b..l
	(detected by 1, t=10503 jiffies, g=33413, q=265 ncpus=2)
task:udevd           state:R  running task     stack:23584 pid:4383  ppid:3638   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:__sanitizer_cov_trace_pc+0x0/0x60 kernel/kcov.c:212
Code: 2e 0f 1f 84 00 00 00 00 00 90 53 48 89 fb e8 17 00 00 00 48 8b 3d d0 a6 9e 0c 48 89 de 5b e9 37 58 4f 00 00 00 cc cc 00 00 cc <48> 8b 04 24 65 48 8b 0d a4 9e 81 7e 65 8b 15 a5 9e 81 7e 81 e2 00
RSP: 0018:ffffc900041c7348 EFLAGS: 00000202
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 92548dad60854c00
RDX: ffff8880271dbb80 RSI: ffffffff8adefc80 RDI: ffffffff8adefc40
RBP: 0000000000000001 R08: dffffc0000000000 R09: fffffbfff215c449
R10: fffffbfff215c449 R11: 1ffffffff215c448 R12: 00000000000001de
R13: dffffc0000000000 R14: 00007f49ded1dfe7 R15: 0000000000000000
 rcu_read_unlock include/linux/rcupdate.h:820 [inline]
 is_bpf_text_address+0x209/0x2a0 kernel/bpf/core.c:737
 kernel_text_address+0x9c/0xd0 kernel/extable.c:125
 __kernel_text_address+0x9/0x30 kernel/extable.c:79
 unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
 arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0x98/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 __kasan_slab_alloc+0x6b/0x80 mm/kasan/common.c:328
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook+0x4b/0x480 mm/slab.h:737
 kmem_cache_alloc_bulk+0x3ba/0x4e0 mm/slub.c:3880
 mt_alloc_bulk lib/maple_tree.c:157 [inline]
 mas_alloc_nodes+0x449/0x890 lib/maple_tree.c:1299
 mas_node_count_gfp lib/maple_tree.c:1359 [inline]
 mas_preallocate+0x161/0x3c0 lib/maple_tree.c:5807
 __vma_adjust+0x2e2/0x1c60 mm/mmap.c:724
 vma_merge+0x8fe/0x9c0 mm/mmap.c:-1
 mprotect_fixup+0x418/0x7f0 mm/mprotect.c:605
 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: 0033:0x7f49ded1dfe7
RSP: 002b:00007ffdcc667c18 EFLAGS: 00000246 ORIG_RAX: 000000000000000a
RAX: ffffffffffffffda RBX: 0000000000000200 RCX: 00007f49ded1dfe7
RDX: 0000000000000001 RSI: 0000000000000200 RDI: 00007f49df3d8000
RBP: 0000557276ca5f80 R08: 0000000000000000 R09: 0000000000000200
R10: 0000557276ca5fe0 R11: 0000000000000246 R12: 0000000000000018
R13: 0000000000000400 R14: 0000557276cabc68 R15: 00007f49df58439c
 </TASK>
rcu: rcu_preempt kthread starved for 10550 jiffies! g33413 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:26720 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:1965
 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: 1 PID: 7255 Comm: syz.5.596 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: f5 ff 0f 1f 00 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 3e 18 42 f7 48 89 df e8 96 dd 42 f7 e8 61 d1 65 f7 fb bf 01 00 00 00 <e8> e6 5a 36 f7 65 8b 05 e7 13 e1 75 85 c0 74 02 5b c3 e8 34 25 df
RSP: 0018:ffffc90004d07bb8 EFLAGS: 00000286
RAX: 29703e214109bd00 RBX: ffff888027b36f00 RCX: 29703e214109bd00
RDX: dffffc0000000000 RSI: ffffffff8a8c0500 RDI: 0000000000000001
RBP: 1ffff11004e1a29d R08: dffffc0000000000 R09: ffffed1004f66de1
R10: ffffed1004f66de1 R11: 1ffff11004f66de0 R12: ffff888026548920
R13: 0000000000000000 R14: dffffc0000000000 R15: ffff888026548938
FS:  00007fe1b703c6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000005d209000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 spin_unlock_irq include/linux/spinlock.h:401 [inline]
 get_signal+0x1163/0x1350 kernel/signal.c:2874
 arch_do_signal_or_restart+0xb0/0x1230 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
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe1b618eba9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe1b703c0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fe1b63d6188 RCX: 00007fe1b618eba9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fe1b63d6188
RBP: 00007fe1b63d6180 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe1b63d6218 R14: 00007ffeb1adac70 R15: 00007ffeb1adad58
 </TASK>