[v6.1] INFO: rcu detected stall in v4l2_release

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f89b6e15694c Linux 6.1.149
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16df6a42580000
kernel config: https://syzkaller.appspot.com/x/.config?x=115cdcc5760d448b
dashboard link: https://syzkaller.appspot.com/bug?extid=d73e65b2a807a5e610e6
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/394a7db0dd9e/disk-f89b6e15.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fbc1ab2ec301/vmlinux-f89b6e15.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6d7c129efafb/bzImage-f89b6e15.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d73e65...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5104/1:b..l
(detected by 0, t=10502 jiffies, g=14117, q=76 ncpus=2)
task:syz.4.203 state:R running task stack:24352 pid:5104 ppid:4265 flags:0x00004000
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:unwind_next_frame+0x2e/0x20b0 arch/x86/kernel/unwind_orc.c:424
Code: 56 41 55 41 54 53 48 81 ec a0 00 00 00 48 89 fb 49 be 00 00 00 00 00 fc ff df 48 8d 6f 48 48 89 e8 48 c1 e8 03 48 89 44 24 28 <42> 80 3c 30 00 74 08 48 89 ef e8 c3 87 98 00 4c 8b 63 48 4c 8d 7b
RSP: 0018:ffffc9000ef076b0 EFLAGS: 00000a06
RAX: 1ffff92001de0efa RBX: ffffc9000ef07788 RCX: 0000000080000000
RDX: dffffc0000000000 RSI: ffffffff81c58124 RDI: ffffc9000ef07788
RBP: ffffc9000ef077d0 R08: ffffc9000ef07850 R09: 0000000000000000
R10: fffff52001de0efd R11: 1ffff92001de0efb R12: ffff888024ea1dc0
R13: 1ffff92001de0f1c R14: dffffc0000000000 R15: ffffc9000ef07788
arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x98/0xe0 kernel/stacktrace.c:122
save_stack+0xf3/0x1e0 mm/page_owner.c:127
__reset_page_owner+0x51/0x1a0 mm/page_owner.c:148
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
v4l2_m2m_ctx_release+0x1a/0x30 drivers/media/v4l2-core/v4l2-mem2mem.c:1273
vicodec_release+0x93/0x110 drivers/media/test-drivers/vicodec/vicodec-core.c:1933
v4l2_release+0x1f9/0x390 drivers/media/v4l2-core/v4l2-dev.c:456
__fput+0x22c/0x920 fs/file_table.c:320
task_work_run+0x1ca/0x250 kernel/task_work.c:203
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
exit_to_user_mode_prepare+0xb1/0x140 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: 0033:0x7f414ed8ebe9
RSP: 002b:00007ffe52ac8d78 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f414efc7da0 RCX: 00007f414ed8ebe9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f414efc7da0 R08: 0000000000000214 R09: 0000001e52ac906f
R10: 00007f414efc7cb0 R11: 0000000000000246 R12: 000000000001e605
R13: 00007f414efc6180 R14: ffffffffffffffff R15: 00007ffe52ac8e90
</TASK>
rcu: rcu_preempt kthread starved for 10457 jiffies! g14117 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: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: 0 PID: 0 Comm: swapper/0 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 37 b2 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 87 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:ffffffff8c807d88 EFLAGS: 000002c6
RAX: 0efcb389ba495a00 RBX: ffffffff8a213f27 RCX: 0efcb389ba495a00
RDX: 0000000000000001 RSI: ffffffff8a8c0300 RDI: ffffffff8adefae0
RBP: ffffffff8c807ec0 R08: dffffc0000000000 R09: ffffed10171c6af6
R10: ffffed10171c6af6 R11: 1ffff110171c6af5 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8c8bc680 R15: 1ffffffff1c3ee66
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000008030 CR3: 000000002993a000 CR4: 00000000003506f0
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
rest_init+0x2dc/0x300 init/main.c:733
arch_call_rest_init+0xa/0xa init/main.c:893
start_kernel+0x490/0x539 init/main.c:1140
secondary_startup_64_no_verify+0xcf/0xdb
</TASK>


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