syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P17447/1:b..l
	(detected by 0, t=10502 jiffies, g=115329, q=109 ncpus=2)
task:udevd           state:R  running task     stack:23648 pid:17447 ppid:3639   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:lock_is_held_type+0x1/0x190 kernel/locking/lockdep.c:5690
Code: 07 04 00 75 d6 48 c7 c7 20 04 8c 8a 48 c7 c6 60 04 8c 8a e8 f1 36 35 f7 0f 0b eb bf e8 98 fd ff ff 0f 1f 84 00 00 00 00 00 55 <41> 57 41 56 41 55 41 54 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00
RSP: 0018:ffffc90004527998 EFLAGS: 00000202
RAX: 1ffffffff1966001 RBX: ffffffff8cb55c20 RCX: 7fe33ab524023700
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: ffffffff8cb2aca0
RBP: 0000000000000cc0 R08: dffffc0000000000 R09: fffffbfff215c449
R10: fffffbfff215c449 R11: 1ffffffff215c448 R12: 0000000000000000
R13: 0000000000000098 R14: ffff88807e4fbbac R15: dffffc0000000000
 task_css include/linux/cgroup.h:509 [inline]
 mem_cgroup_from_task+0x96/0x110 mm/memcontrol.c:985
 get_obj_cgroup_from_current+0x163/0x280 mm/memcontrol.c:3023
 memcg_slab_pre_alloc_hook mm/slab.h:485 [inline]
 slab_pre_alloc_hook+0x91/0x310 mm/slab.h:715
 slab_alloc_node mm/slub.c:3279 [inline]
 slab_alloc mm/slub.c:3367 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3374 [inline]
 kmem_cache_alloc+0x56/0x2f0 mm/slub.c:3383
 vm_area_dup+0x23/0x1a0 kernel/fork.c:467
 __split_vma+0xb9/0x500 mm/mmap.c:2363
 do_mas_align_munmap+0x762/0x1220 mm/mmap.c:2501
 do_mas_munmap+0x240/0x2b0 mm/mmap.c:2650
 __vm_munmap+0x18d/0x290 mm/mmap.c:2936
 __do_sys_munmap mm/mmap.c:2961 [inline]
 __se_sys_munmap mm/mmap.c:2958 [inline]
 __x64_sys_munmap+0x5c/0x70 mm/mmap.c:2958
 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: 0033:0x7f29a2b1e097
RSP: 002b:00007ffeb61b51c8 EFLAGS: 00000246 ORIG_RAX: 000000000000000b
RAX: ffffffffffffffda RBX: 00005556fa01a460 RCX: 00007f29a2b1e097
RDX: 00005556fa00a1a8 RSI: 0000000000000200 RDI: 00007f29a3223000
RBP: 00005556fa004cc0 R08: 0000000000000040 R09: 0000000000040000
R10: 00005556fa004cb0 R11: 0000000000000246 R12: 00007f29a33717c0
R13: 00007f29a337339c R14: 0000000000000022 R15: 0000000000000001
 </TASK>
rcu: rcu_preempt kthread starved for 10536 jiffies! g115329 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:27040 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:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 19391 Comm: syz.9.3446 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:lock_acquire+0x6/0x490 kernel/locking/lockdep.c:5630
Code: e9 35 fb ff ff 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 65 8b 05 d1 79 9f 7e a9 00 ff ff 00 0f 95 c0 c3 55 48 89 e5 41 57 <41> 56 41 55 41 54 53 48 83 e4 e0 48 81 ec e0 00 00 00 4c 89 4c 24
RSP: 0018:ffffc9000d1f79a0 EFLAGS: 00000046
RAX: 0000000000000002 RBX: ffff8880b8f2a580 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8880b8f2a598
RBP: ffffc9000d1f79a8 R08: 0000000000000001 R09: 0000000000000000
R10: fffffbfff1c3ed96 R11: 1ffffffff1c3ed95 R12: dffffc0000000000
R13: dffffc0000000000 R14: 0000000000000802 R15: 1ffff92001a3ef38
FS:  00007fd3354af6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8bad9e7dac CR3: 000000007e401000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
 lock_hrtimer_base kernel/time/hrtimer.c:180 [inline]
 hrtimer_start_range_ns+0xec/0xfc0 kernel/time/hrtimer.c:1346
 posixtimer_rearm+0x131/0x340 kernel/time/posix-timers.c:329
 dequeue_signal+0x1b6/0x4b0 kernel/signal.c:704
 get_signal+0x547/0x1350 kernel/signal.c:2751
 arch_do_signal_or_restart+0xb7/0x1240 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: 0033:0x7fd33458efc9
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:00007fd3354af0e8 EFLAGS: 00000246
RAX: fffffffffffffffc RBX: 00007fd3347e6098 RCX: 00007fd33458efc9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fd3347e6098
RBP: 00007fd3347e6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd3347e6128 R14: 00007fffd0d45a80 R15: 00007fffd0d45b68
 </TASK>