linux-kernel - Re: [BUG] WARNING in drm_gem_object_handle_put_unlocked via drm

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Message-ID: <5c81c9d2864287460d69b70f1b3e74a497d71595@intel.com>
Date: Thu, 08 Jan 2026 13:46:29 +0200
From: Jani Nikula <jani.nikula@...ux.intel.com>
To: "WangzXD0325@...look.com" <WangzXD0325@...look.com>,
 "maarten.lankhorst@...ux.intel.com" <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann
 <tzimmermann@...e.de>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
Subject: Re: [BUG] WARNING in drm_gem_object_handle_put_unlocked via
 drm_release

On Thu, 08 Jan 2026, "WangzXD0325@...look.com" <WangzXD0325@...look.com> wrote:
> Hello DRM maintainers,
>
> This is a WARNING bug detected by syzkaller.

As this is an issue detected using a tool, it would be quite helpful to
include the minimal command-line required to reproduce the issue.

That said, I'm not quite sure who is going to step up to debug and fix
the issues. But at at least lowering the bar improves the odds a bit.


BR,
Jani.


> 1. Description
> A kernel WARNING was triggered in drm_gem_object_handle_put_unlocked during the close() syscall on a DRM file descriptor. The issue appears to be related to GEM object handle management during the release process (drm_release).
>
> According to the log, the warning is located at drivers/gpu/drm/drm_gem.c:300.
>
> 2. Environment
> Kernel Branch: mainline
> Kernel Revision: v6.18 
> Kernel Config: https://gist.github.com/manual0/b8f4c12ea784620b3db92dbe56afedbb#file-gistfile1-txt
> Compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0
>
> 3. Syzkaller Report
> WARNING: CPU: 3 PID: 48617 at drivers/gpu/drm/drm_gem.c:300 drm_gem_object_handle_put_unlocked+0x30e/0x3e0
> Modules linked in:
> CPU: 3 UID: 0 PID: 48617 Comm: syz.3.11626 Not tainted 6.18.0 #1 PREEMPT(full) 
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
> RIP: 0010:drm_gem_object_handle_put_unlocked+0x30e/0x3e0
> Call Trace:
>  <TASK>
>  drm_gem_object_release_handle+0xc7/0x200
>  idr_for_each+0x119/0x230 lib/idr.c:208
>  drm_gem_release+0x29/0x40
>  drm_file_free.part.0+0x724/0xcf0
>  drm_close_helper.isra.0+0x183/0x1f0
>  drm_release+0x1ab/0x360
>  __fput+0x402/0xb50 fs/file_table.c:468
>  task_work_run+0x16b/0x260 kernel/task_work.c:227
>  exit_to_user_mode_loop+0xf9/0x130
>  do_syscall_64+0x424/0xfa0 arch/x86/entry/syscall_32.c:308
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>  </TASK>
>
> Best regards,
> Zhi Wang

-- 
Jani Nikula, Intel