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From:   Song Liu <song@kernel.org>
Date:   Thu, 18 May 2023 11:54:23 -0700
Message-ID: <CAPhsuW5a7jB1wsyNiUMM-QuuvLx4omTRgDiywEMDn3NLhnqMzg@mail.gmail.com>
Subject: Re: [RFC PATCH 1/5] mm: intorduce __GFP_UNMAPPED and unmapped_alloc()
To:     Kent Overstreet <kent.overstreet@linux.dev>
Cc:     Mike Rapoport <rppt@kernel.org>, linux-mm@kvack.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Rick Edgecombe <rick.p.edgecombe@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Vlastimil Babka <vbabka@suse.cz>, linux-kernel@vger.kernel.org,
        x86@kernel.org
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On Thu, May 18, 2023 at 10:25=E2=80=AFAM Kent Overstreet
<kent.overstreet@linux.dev> wrote:
>
> On Thu, May 18, 2023 at 10:15:59AM -0700, Song Liu wrote:
> > On Thu, May 18, 2023 at 9:58=E2=80=AFAM Kent Overstreet
> > <kent.overstreet@linux.dev> wrote:
> > >
> > > On Thu, May 18, 2023 at 09:33:20AM -0700, Song Liu wrote:
> > > > I am working on patches based on the discussion in [1]. I am planni=
ng to
> > > > send v1 for review in a week or so.
> > >
> > > For reference, here's my own (early, but functioning :) slab allocato=
r:
> > >
> > > Look forward to comparing!
> >
> > This looks similar to the bpf_prog_pack allocator we use for BPF at the
> > moment. (search for bpf_prog_pack in kernel/bpf/core.c). I guess we
> > can also use bpf_prog_pack for bcachefs for now.
>
> The code in bpf/core.c does a _lot_, my preference would be to split
> that up and refactor the bpf code to use something generic :)

The code is actually splitted into two parts:

   bpf_prog_pack_[alloc|free] vs. bpf_jit_binary_pack_[alloc|free].

The latter has logic just for BPF. But the former can be reused by
other users (maybe with a little refactoring).

Once the vmap_area based solution is committed, we will replace the
former with the new allocator.

Thanks,
Song