linux-kernel - Re: [PATCH v2] drm/vmwgfx: Work around VMW_ALLOC

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Date:   Fri, 24 Feb 2023 11:29:36 +0800
From:   Meng Tang <tangmeng@...ontech.com>
To:     Zack Rusin <zackr@...are.com>, "daniel@...ll.ch" <daniel@...ll.ch>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Linux-graphics-maintainer <Linux-graphics-maintainer@...are.com>,
        "airlied@...il.com" <airlied@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] drm/vmwgfx: Work around VMW_ALLOC_DMABUF



On 2023/2/24 11:13, Zack Rusin wrote:
> 
> That's correct. That's the way this works. The ioctl is allocating a buffer, there's
> no infinite space for buffers on a system and, given that your app just allocates
> and never frees buffers, at some point the space will run out and the ioctl will
> return a failure.
> 
Do you mean that users without certain privileges can access allocate a 
buffer because it is designed like this? so we don't need to block 
users without certain privileges to VMW_ALLOC_DMABUF success?
> As to the stack trace, I'm not sure what kernel you were testing it on so I don't
> have access to the full log but I can't reproduce it and there was a change fixing
> exactly this (i.e. buffer failed allocation but we were still accessing it) that was
> fixed in in 6.2 in commit 1a6897921f52 ("drm/vmwgfx: Stop accessing buffer objects
> which failed init") the change was backported as well, so you should be able to
> verify on any kernel with it.
> 
> z
> 
Thank you, the kernel version of my environment is lower than 6.2, I 
will verify on my kernel with commit 1a6897921f52 ("drm/vmwgfx: Stop 
accessing buffer objects which failed init").