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

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Message-ID: <20230531135120.GA395338@kernel.org>
Date:   Wed, 31 May 2023 16:51:20 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     Song Liu <song@...nel.org>
Cc:     Kent Overstreet <kent.overstreet@...ux.dev>,
        linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
        mcgrof@...nel.org, peterz@...radead.org, tglx@...utronix.de,
        x86@...nel.org
Subject: Re: [PATCH 0/3] Type aware module allocator

On Tue, May 30, 2023 at 03:37:24PM -0700, Song Liu wrote:
> On Mon, May 29, 2023 at 3:45 AM Mike Rapoport <rppt@...nel.org> wrote:
> >
> > On Sat, May 27, 2023 at 10:58:37PM -0700, Song Liu wrote:
> > > On Sat, May 27, 2023 at 12:04 AM Kent Overstreet
> > > <kent.overstreet@...ux.dev> wrote:
> > > >
> > > > I think this needs to back to the drawing board and we need something
> > > > simpler just targeted at executable memory; architecture specific
> > > > options should definitely _not_ be part of the exposed interface.
> > >
> > > 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.
> >
> > I'm for creating a new allocator that will replace module_alloc(). This
> > will give us a clean abstraction that modules and all the rest will use and
> > it will make easier to plug binpack or another allocator instead of
> > vmalloc.
> >
> > Another point is with a new allocator we won't have weird dependencies on
> > CONFIG_MODULE in e.g. bpf and kprobes.
> >
> > I'll have something ready to post as an RFC in a few days.
> 
> I guess this RFC is similar to unmapped_alloc()? If it replaces
> vmalloc, we can probably trim this set down a bit (remove
> mod_alloc_params and vmalloc_params, etc.).

No, it's not a new allocator. I'm trying to create an API for code
allocations that can accommodate all the architectures and it won't be a
part of modules code. The modules will use the new API just like every
other subsystem that needs to allocate code.

I've got a core part of it here:

https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git/log/?h=jitalloc/v1

and I hope I'll get it ready to post this week.

> Thanks,
> Song

-- 
Sincerely yours,
Mike.