linux-kernel - Re: [PATCH v2] drm: Account property blob allocations to memcg

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Message-ID: <20260113-kickass-sensible-basilisk-66d487@houat>
Date: Tue, 13 Jan 2026 16:56:31 +0100
From: Maxime Ripard <mripard@...nel.org>
To: Xiao Kan <814091656@...com>
Cc: maarten.lankhorst@...ux.intel.com, tzimmermann@...e.de, 
	airlied@...il.com, simona@...ll.ch, dri-devel@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org, w@....eu, security@...nel.org, kanxiao666@...il.com, 
	xiao.kan@...sung.com
Subject: Re: [PATCH v2] drm: Account property blob allocations to memcg

Hi,

On Mon, Jan 05, 2026 at 11:14:13AM -0500, Xiao Kan wrote:
> DRM_IOCTL_MODE_CREATEPROPBLOB allows userspace to allocate arbitrary-sized
> property blobs backed by kernel memory.
> 
> Currently, the blob data allocation is not accounted to the allocating
> process's memory cgroup, allowing unprivileged users to trigger unbounded
> kernel memory consumption and potentially cause system-wide OOM.
> 
> Mark the property blob data allocation with GFP_ACCOUNT so that the memory
> is properly charged to the caller's memcg. This ensures existing cgroup
> memory limits apply and prevents uncontrolled kernel memory growth without
> introducing additional policy or per-file limits.
> 
> Changes since v1:
>   - Drop the per-drm_file blob count limit.
>   - Account blob data allocations to memcg via GFP_KERNEL_ACCOUNT instead.
> 
> Signed-off-by: Xiao Kan <814091656@...com>
> Signed-off-by: Xiao Kan <xiao.kan@...sung.com>

It looks like you sent two different patches labelled v2? Sending a new
version in itself is not a problem (and even encourage), but you should
always bump the version number.

Maxime

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