Re: [PATCH v8 0/6] mm/vmalloc: free unused pages on vrealloc() shrink

[Danilo Krummrich]

On Fri Mar 27, 2026 at 7:37 PM CET, Andrew Morton wrote:
> Are we able to describe how much memory this change might save under
> various scenarios?  If the savings are impressively large then that
> would get attention.

We already have a workaround in place for shrinking vmalloc buffers through a
deep copy in Rust alloc.

Given that binder, which motivated this workaround, uses it already, it suggests
that the savings are significant enough to accept this overhead (I assume Alice
has some numbers).

So, I assume the more interesting question would be how badly the deep copy
hurts binder compared to unmapping and freeing spare pages.