[PATCH v2] drm/ttm: Silence randstruct warning about casting struct file

[Al Viro]

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?