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	Fri, 02 May 2025 04:31:49 +0000
Date: Fri, 2 May 2025 05:31:49 +0100
From: Al Viro <viro@zeniv.linux.org.uk>
To: Matthew Brost <matthew.brost@intel.com>
Cc: Kees Cook <kees@kernel.org>,
	Thomas =?iso-8859-1?Q?Hellstr=F6m?= <thomas.hellstrom@linux.intel.com>,
	Christian Koenig <christian.koenig@amd.com>,
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	Huang Rui <ray.huang@amd.com>,
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	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
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	linux-hardening@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>
Subject: Re: [PATCH v2] drm/ttm: Silence randstruct warning about casting
 struct file
Message-ID: <20250502043149.GW2023217@ZenIV>
References: <20250502002437.it.851-kees@kernel.org>
 <aBQqOCQZrHBBbPbL@lstrano-desk.jf.intel.com>
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Sender: Al Viro <viro@ftp.linux.org.uk>

On Thu, May 01, 2025 at 09:26:25PM -0700, Matthew Brost wrote:

> I;m fairly certain is just aliasing... but I do understand a file cannot
> be embedded. Would comment help here indicating no other fields should
> be added to ttm_backup without struct file be converted to pointer or
> that just to risky?

What exactly are you trying to do there?  IOW, is that always supposed to
be a struct file, or something dependent upon something in struct ttm_tt
instance, or...?

And what is the lifecycle of that thing?  E.g. what is guaranteed about
ttm_backup_fini() vs. functions accessing the damn thing?  Are they
serialized on something/tied to lifecycle stages of struct ttm_tt?