linux-kernel - Re: [PATCH 0/3] Type aware module allocator

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Message-ID: <ZHTuBdlhSI0mmQGE@moria.home.lan>
Date:   Mon, 29 May 2023 14:25:09 -0400
From:   Kent Overstreet <kent.overstreet@...ux.dev>
To:     Song Liu <song@...nel.org>
Cc:     linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
        mcgrof@...nel.org, peterz@...radead.org, tglx@...utronix.de,
        x86@...nel.org, rppt@...nel.org
Subject: Re: [PATCH 0/3] Type aware module allocator

On Sat, May 27, 2023 at 10:58:37PM -0700, Song Liu wrote:
> I don't think we are exposing architecture specific options to users.
> Some layer need to handle arch specifics. If the new allocator is
> built on top of module_alloc, module_alloc is handling that. If the new
> allocator is to replace module_alloc, it needs to handle arch specifics.

Ok, I went back and read more thoroughly, I got this part wrong. The
actual interface is the mod_mem_type enum, not mod_alloc_params or
vmalloc_params.

So this was my main complaint, but this actually looks ok now.

It would be better to have those structs in a .c file, not the header
file - it looks like those are the public interface the way you have it.

> > The memory protection interface also needs to go, we've got a better
> > interface to model after (text_poke(), although that code needs work
> > too!). And the instruction fill features need a thorough justification
> > if they're to be included.
> 
> I guess the first step to use text_poke() is to make it available on all
> archs? That doesn't seem easy to me.

We just need a helper that either calls text_poke() or does the page
permission dance in a single place.

If we do the same thing for other mod_mem_types, we could potentially
allow them to be shared on hugepages too.