syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P13258/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=93869, q=907 ncpus=2)
task:syz.2.1872      state:R  running task     stack:24104 pid:13258 tgid:13258 ppid:11279  task_flags:0x400040 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7288
 irqentry_exit+0x6f/0x90 kernel/entry/common.c:197
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:206 [inline]
RIP: 0010:unwind_next_frame+0x1c9/0x2390 arch/x86/kernel/unwind_orc.c:494
Code: 08 4c 89 ff e8 d8 5d b0 00 4d 8b 27 48 83 f3 01 48 c7 c2 40 41 88 8b 49 29 dc 0f 84 a2 01 00 00 49 81 fc 00 00 00 81 0f 92 c0 <49> 81 fc 7c e3 7d 8b 0f 93 c1 08 c1 0f 85 e8 00 00 00 48 c7 c0 00
RSP: 0018:ffffc900038af678 EFLAGS: 00000202
RAX: 1ffff92000715e00 RBX: 0000000000000001 RCX: 667c002879b37100
RDX: ffffffff8b884140 RSI: ffffffff8be33960 RDI: ffffffff8be33920
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffffff8172c195
R10: ffffc900038af798 R11: ffffffff81ac3ae0 R12: ffffffff87c99429
R13: ffffc900038af798 R14: ffffc900038af748 R15: ffffc900038af790
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:243 [inline]
 __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2422 [inline]
 slab_free mm/slub.c:4695 [inline]
 kfree+0x18e/0x440 mm/slub.c:4894
 vfree+0x353/0x400 mm/vmalloc.c:3439
 vb2_vmalloc_put+0x68/0xb0 drivers/media/common/videobuf2/videobuf2-vmalloc.c:68
 __vb2_buf_mem_free+0x119/0x2d0 drivers/media/common/videobuf2/videobuf2-core.c:275
 __vb2_free_mem drivers/media/common/videobuf2/videobuf2-core.c:571 [inline]
 __vb2_queue_free+0x414/0xb00 drivers/media/common/videobuf2/videobuf2-core.c:599
 vb2_core_queue_release+0x6b/0x150 drivers/media/common/videobuf2/videobuf2-core.c:2695
 v4l2_m2m_ctx_release+0x1e/0x40 drivers/media/v4l2-core/v4l2-mem2mem.c:1276
 vim2m_release+0xd5/0x140 drivers/media/test-drivers/vim2m.c:1458
 v4l2_release+0x1ea/0x3b0 drivers/media/v4l2-core/v4l2-dev.c:458
 __fput+0x449/0xa70 fs/file_table.c:468
 task_work_run+0x1d1/0x260 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa53b58ebe9
RSP: 002b:00007fa53b8efb88 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fa53b7c7da0 RCX: 00007fa53b58ebe9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007fa53b7c7da0 R08: 0000000000000208 R09: 0000001e3b8efe7f
R10: 00007fa53b7c7cb0 R11: 0000000000000246 R12: 00000000000a8d1c
R13: 00007fa53b7c5fa0 R14: ffffffffffffffff R15: 00007fa53b8efca0
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g93869 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=46733
rcu: rcu_preempt kthread starved for 10502 jiffies! g93869 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27432 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </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 UID: 0 PID: 13269 Comm: syz.3.1873 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:do_raw_spin_unlock+0x11/0x240 kernel/locking/spinlock_debug.c:139
Code: 85 00 e9 60 ff ff ff 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 0f 1f 00 55 41 57 41 56 41 55 41 54 53 48 89 fb <49> bc 00 00 00 00 00 fc ff df 4c 8d 77 04 4c 89 f0 48 c1 e8 03 42
RSP: 0018:ffffc900038cfa68 EFLAGS: 00000082
RAX: b114d67544796e00 RBX: ffffffff8e916180 RCX: b114d67544796e00
RDX: 0000000000000001 RSI: ffffffff8dba895d RDI: ffffffff8e916180
RBP: ffffc900038cfb30 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000719f44 R12: dffffc0000000000
R13: ffff8880309f8424 R14: ffffffff8e916180 R15: 1ffff92000719f54
FS:  0000000000000000(0000) GS:ffff888125c15000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055557e4eb5c8 CR3: 0000000032122000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000053d850c4
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:150 [inline]
 _raw_spin_unlock_irqrestore+0x78/0x110 kernel/locking/spinlock.c:194
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 vga_put drivers/pci/vgaarb.c:553 [inline]
 vga_arb_release+0x40c/0xaa0 drivers/pci/vgaarb.c:1455
 __fput+0x449/0xa70 fs/file_table.c:468
 task_work_run+0x1d1/0x260 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x6b5/0x2300 kernel/exit.c:961
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1102
 __do_sys_exit_group kernel/exit.c:1113 [inline]
 __se_sys_exit_group kernel/exit.c:1111 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1111
 x64_sys_call+0x21f7/0x2200 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb06b58ebe9
Code: Unable to access opcode bytes at 0x7fb06b58ebbf.
RSP: 002b:00007fb06b8ef578 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000000000000000b RCX: 00007fb06b58ebe9
RDX: 00007fb06b5461d7 RSI: 0000000000000000 RDI: 000000000000000b
RBP: 0000000000000003 R08: 00007fb06b8efa27 R09: 000000000000000b
R10: 00007fb06b7c5fa0 R11: 0000000000000246 R12: 00007fb06b7c627c
R13: 00007fb06b7c6270 R14: 00000000000015ad R15: 0000000000000006
 </TASK>