On Wed, 1 Nov 2023 at 10:13, Luis Chamberlain <mcgrof@xxxxxxxxxx> wrote:
>
> The only thing worth highligthing is that gzip moves to use vmalloc() instead of
> kmalloc just as we had a fix for this for zstd on v6.6-rc1.
Actually, that's almost certainly entirely the wrong thing to do.
Unless you *know* that the allocation is large, you shouldn't use
vmalloc(). And since kmalloc() has worked fine, you most definitely
don't know that.
So we have 'kvmalloc()' *exactly* for this reason, which is a "use
kmalloc, unless that is too small, then use vmalloc".
kmalloc() isn't just about "use physically contiguous allocations".
It's also more memory-efficient, and a *lot* faster than vmalloc(),
which has to play VM tricks.
So this "just switch to vmalloc()" is entirely wrong.
Linus
