Re: [PATCH 00/13] mm: jit/text allocator

[Song Liu]

On Sun, Jun 4, 2023 at 11:02 AM Kent Overstreet
<kent.overstreet@xxxxxxxxx> wrote:
>
> On Fri, Jun 02, 2023 at 11:20:58AM -0700, Song Liu wrote:
> > IIUC, arm64 uses VMALLOC address space for BPF programs. The reason
> > is each BPF program uses at least 64kB (one page) out of the 128MB
> > address space. Puranjay Mohan (CC'ed) is working on enabling
> > bpf_prog_pack for arm64. Once this work is done, multiple BPF programs
> > will be able to share a page. Will this improvement remove the need to
> > specify a different address range for BPF programs?
>
> Can we please stop working on BPF specific sub page allocation and focus
> on doing this in mm/? This never should have been in BPF in the first
> place.

That work is mostly independent of the allocator work we are discussing here.
The goal Puranjay's work is to enable the arm64 BPF JIT engine to use a
ROX allocator. The allocator could be the bpf_prog_pack allocator, or jitalloc,
or module_alloc_type. Puranjay is using bpf_prog_alloc for now. But once
jitalloc or module_alloc_type (either one) is merged, we will migrate BPF
JIT engines (x86_64 and arm64) to the new allocator and then tear down
bpf_prog_pack.

Does this make sense?

Thanks,
Song