syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6424/1:b..l
	(detected by 1, t=10503 jiffies, g=56881, q=219 ncpus=2)
task:udevd           state:R  running task     stack:24944 pid:6424  ppid:3638   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:debug_lockdep_rcu_enabled+0x9/0x30 kernel/rcu/update.c:280
Code: 40 0f 8c 8a 48 c7 c6 20 33 8c 8a e8 41 1a 20 f7 0f 0b eb d1 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 31 c0 83 3d 07 15 f2 03 00 <74> 1d 83 3d 92 48 f2 03 00 74 14 65 48 8b 0d 24 a4 d4 75 31 c0 83
RSP: 0018:ffffc900035373c8 EFLAGS: 00000202
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88802b67d940
RDX: 0000000000000000 RSI: 00007f3f7111dfe7 RDI: ffffffffa0004ac0
RBP: 0000000000000000 R08: dffffc0000000000 R09: 1ffffffff215ee48
R10: dffffc0000000000 R11: fffffbfff215ee49 R12: 0000000000000092
R13: dffffc0000000000 R14: 00007f3f7111dfe7 R15: 0000000000000000
 rcu_read_unlock include/linux/rcupdate.h:820 [inline]
 is_bpf_text_address+0x1ec/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+0xa6/0xf0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x131/0x1a0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 kmem_cache_free+0xf7/0x290 mm/slub.c:3709
 anon_vma_chain_free mm/rmap.c:146 [inline]
 unlink_anon_vmas+0x2c8/0x660 mm/rmap.c:420
 anon_vma_merge include/linux/rmap.h:166 [inline]
 __vma_adjust+0x160c/0x1cd0 mm/mmap.c:858
 vma_merge+0x8cf/0xa00 mm/mmap.c:1072
 mprotect_fixup+0x428/0x800 mm/mprotect.c:605
 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: 0033:0x7f3f7111dfe7
RSP: 002b:00007ffecbdf1948 EFLAGS: 00000246 ORIG_RAX: 000000000000000a
RAX: ffffffffffffffda RBX: 0000000000000200 RCX: 00007f3f7111dfe7
RDX: 0000000000000001 RSI: 0000000000000200 RDI: 00007f3f717a2000
RBP: 000055acd3cc0050 R08: 0000000000000000 R09: 0000000000000200
R10: 000055acd3cc00b0 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000004a00 R14: 000055acd3ccb448 R15: 00007f3f718cc39c
 </TASK>
rcu: rcu_preempt kthread starved for 10522 jiffies! g56881 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:28016 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:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 9508 Comm: syz.1.1086 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:__local_bh_enable_ip+0x122/0x1c0 kernel/softirq.c:416
Code: d8 65 01 05 f8 08 b3 7e 65 8b 05 f1 08 b3 7e a9 00 ff ff 00 75 19 48 c7 c7 60 06 8b 8a e8 76 74 de 08 65 66 8b 05 0e 3a b4 7e <66> 85 c0 75 54 bf 01 00 00 00 e8 6f 85 09 00 e8 1a 77 39 00 fb 65
RSP: 0018:ffffc90004237c00 EFLAGS: 00000086
RAX: 000000000000018a RBX: 0000000000000200 RCX: 9e96ed8d2bc6e400
RDX: dffffc0000000000 RSI: ffffffff8a8b0660 RDI: ffffffff8adf0d20
RBP: ffffc90004237c90 R08: ffff88807ba75947 R09: 1ffff1100f74eb28
R10: dffffc0000000000 R11: ffffed100f74eb29 R12: ffffffff812fa606
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff92000846f80
FS:  00007fa89e1f66c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c408b9c CR3: 000000006851d000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 handle_signal arch/x86/kernel/signal.c:844 [inline]
 arch_do_signal_or_restart+0xf6b/0x1350 arch/x86/kernel/signal.c:873
 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:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa89ffbbd90
Code: 83 c0 16 83 e0 f7 74 12 50 48 8d 3d 3a 22 07 00 e8 65 65 f9 ff 0f 1f 44 00 00 c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 <83> ff 21 74 0b c3 66 2e 0f 1f 84 00 00 00 00 00 55 53 48 89 f3 48
RSP: 002b:00007fa89e1f5a78 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 00007fa8a0215fa0 RCX: 00007fa89ff9c819
RDX: 00007fa89e1f5a80 RSI: 00007fa89e1f5bb0 RDI: 0000000000000021
RBP: 00007fa8a0032c91 R08: 0000000000001000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa8a0216038 R14: 00007fa8a0215fa0 R15: 00007ffe8ca9ea38
 </TASK>