syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P7715/1:b..l
	(detected by 1, t=10502 jiffies, g=36501, q=409 ncpus=2)
task:syz.2.918       state:R  running task     stack:23488 pid:7715  ppid:4266   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+0x13a/0x190 kernel/locking/lockdep.c:5710
Code: 75 40 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 46 41 f7 c5 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 <48> 3b 44 24 08 75 3c 89 e8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffffc90004ddf828 EFLAGS: 00000206
RAX: 1406fdafcfaf1700 RBX: ffff8880734b5940 RCX: 1406fdafcfaf1700
RDX: 0000000000000000 RSI: ffffffff8a8c1480 RDI: ffffffff8adefaa0
RBP: 0000000000000001 R08: dffffc0000000000 R09: fffffbfff215c449
R10: fffffbfff215c449 R11: 1ffffffff215c448 R12: 0000000000000002
R13: 0000000000000246 R14: ffffffff8cb2a9e0 R15: ffff8880734b6470
 lookup_page_ext mm/page_ext.c:277 [inline]
 page_ext_get+0x18f/0x2a0 mm/page_ext.c:158
 __reset_page_owner+0x31/0x1a0 mm/page_owner.c:144
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1459 [inline]
 free_pcp_prepare mm/page_alloc.c:1509 [inline]
 free_unref_page_prepare+0x8b4/0x9a0 mm/page_alloc.c:3384
 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3479
 __vunmap+0x856/0xa00 mm/vmalloc.c:2726
 vb2_vmalloc_put+0x64/0xa0 drivers/media/common/videobuf2/videobuf2-vmalloc.c:68
 __vb2_buf_mem_free+0x113/0x2c0 drivers/media/common/videobuf2/videobuf2-core.c:266
 __vb2_free_mem drivers/media/common/videobuf2/videobuf2-core.c:496 [inline]
 __vb2_queue_free+0x447/0xd80 drivers/media/common/videobuf2/videobuf2-core.c:541
 vb2_core_queue_release+0x5b/0x80 drivers/media/common/videobuf2/videobuf2-core.c:2477
 vb2_queue_release drivers/media/common/videobuf2/videobuf2-v4l2.c:934 [inline]
 _vb2_fop_release drivers/media/common/videobuf2/videobuf2-v4l2.c:1119 [inline]
 vb2_fop_release+0x160/0x1e0 drivers/media/common/videobuf2/videobuf2-v4l2.c:1133
 v4l2_release+0x266/0x390 drivers/media/v4l2-core/v4l2-dev.c:459
 __fput+0x22c/0x920 fs/file_table.c:320
 task_work_run+0x1ca/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0x93e/0x2400 kernel/exit.c:880
 do_group_exit+0x217/0x2d0 kernel/exit.c:1022
 __do_sys_exit_group kernel/exit.c:1033 [inline]
 __se_sys_exit_group kernel/exit.c:1031 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1031
 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: 0033:0x7fdac138eba9
RSP: 002b:00007ffdae91fcb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdac138eba9
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffdae91fd1c R08: 0000001dae91fdaf R09: 00000000000927c0
R10: 00000000000160cc R11: 0000000000000246 R12: 00000000000000a5
R13: 00000000000927c0 R14: 00000000000454f2 R15: 00007ffdae91fd70
 </TASK>
rcu: rcu_preempt kthread starved for 9178 jiffies! g36501 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:28096 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: 0 Comm: swapper/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:742
Code: 48 89 df e8 d7 b6 af f7 e9 4c ff ff ff e8 fd 07 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 66 90 0f 00 2d 07 63 65 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:ffffc90000177de8 EFLAGS: 000002c6
RAX: f9711cb1fbe93d00 RBX: ffffffff8a213fa7 RCX: f9711cb1fbe93d00
RDX: 0000000000000001 RSI: ffffffff8a8c0300 RDI: ffffffff8adefaa0
RBP: ffffc90000177f20 R08: dffffc0000000000 R09: ffffed10171e6afa
R10: ffffed10171e6afa R11: 1ffff110171e6af9 R12: 0000000000000001
R13: dffffc0000000000 R14: ffff88813fed9dc0 R15: 1ffffffff1c3ee8e
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa47a396b49 CR3: 0000000023c48000 CR4: 00000000003506e0
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
 start_secondary+0xe4/0xf0 arch/x86/kernel/smpboot.c:281
 secondary_startup_64_no_verify+0xcf/0xdb
 </TASK>