linux-kernel - Re: [PATCH v3 bpf RESEND 3/4] module: introduce module_alloc

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Message-ID: <YliOC455r6XmE24Q@bombadil.infradead.org>
Date:   Thu, 14 Apr 2022 14:11:39 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Song Liu <song@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     bpf <bpf@...r.kernel.org>, Linux-MM <linux-mm@...ck.org>,
        open list <linux-kernel@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Kernel Team <kernel-team@...com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
        Christoph Hellwig <hch@...radead.org>, imbrenda@...ux.ibm.com
Subject: Re: [PATCH v3 bpf RESEND 3/4] module: introduce module_alloc_huge

On Thu, Apr 14, 2022 at 02:03:17PM -0700, Song Liu wrote:
> Hi Luis,
> 
> On Thu, Apr 14, 2022 at 1:34 PM Luis Chamberlain <mcgrof@...nel.org> wrote:
> >
> > On Thu, Apr 14, 2022 at 12:59:13PM -0700, Song Liu wrote:
> > > Introduce module_alloc_huge, which allocates huge page backed memory in
> > > module memory space. The primary user of this memory is bpf_prog_pack
> > > (multiple BPF programs sharing a huge page).
> > >
> > > Signed-off-by: Song Liu <song@...nel.org>
> >
> > See modules-next [0], as modules.c has been chopped up as of late.
> > So if you want this to go throug modules this will need to rebased
> > on that tree. fortunately the amount of code in question does not
> > seem like much.
> >
> > [0] https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux.git/log/?h=modules-next
> 
> We are hoping to ship this with to 5.18, as the set addresses some issue with
> huge page backed vmalloc. I guess we cannot ship it via modules-next branch.
> 

Huh, you intend this to go in as a fix for v5.18 (already released) once
properly reviewed?  This seems quite large... for a fix.

> How about we ship module_alloc_huge() to 5.18 in module.c for now, and once
> we update modules-next branch, I will send another patch to clean it up?

I rather set the expectations right about getting such a large fix in
for v5.18. I haven't even sat down to review all the changes in light of
this, but a cursorary glance seems to me it's rather "large" for a fix.

  Luis