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Message-ID: <C7D06958-F806-4F73-9825-22B373E6B479@fb.com>
Date: Wed, 12 Oct 2022 19:03:28 +0000
From: Song Liu <songliubraving@...a.com>
To: Peter Zijlstra <peterz@...radead.org>
CC: Linux-MM <linux-mm@...ck.org>, lkml <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
X86 ML <x86@...nel.org>, Christoph Hellwig <hch@....de>,
Kernel Team <Kernel-team@...com>,
"Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
"Hansen, Dave" <dave.hansen@...el.com>,
Uladzislau Rezki <urezki@...il.com>,
Luis Chamberlain <mcgrof@...nel.org>,
Song Liu <song@...nel.org>
Subject: Re: [RFC v2 0/4] vmalloc_exec for modules and BPF programs
Hi Peter,
> On Oct 7, 2022, at 4:43 PM, Song Liu <song@...nel.org> wrote:
>
> Changes RFC v1 => RFC v2:
> 1. Major rewrite of the logic of vmalloc_exec and vfree_exec. They now
> work fine with BPF programs (patch 1, 2, 4). But module side (patch 3)
> still need some work.
>
> This set is a prototype that allows dynamic kernel text (modules, bpf
> programs, various trampolines, etc.) to share huge pages. The idea is
> similar to Peter's suggestion in [1]. Please refer to each patch for
> more detais.
>
> The ultimate goal is to only host kernel text in 2MB pages (for x86_64).
>
> Please share your comments on this.
>
> Thanks!
>
> [1] https://lore.kernel.org/bpf/Ys6cWUMHO8XwyYgr@hirez.programming.kicks-ass.net/
> [2] RFC v1: https://lore.kernel.org/linux-mm/20220818224218.2399791-3-song@kernel.org/T/
Could you please share your comments on this version? Is this the
right direction to move this work?
Thanks,
Song
>
> Song Liu (4):
> vmalloc: introduce vmalloc_exec and vfree_exec
> bpf: use vmalloc_exec
> modules, x86: use vmalloc_exec for module core
> vmalloc_exec: share a huge page with kernel text
>
> arch/x86/Kconfig | 1 +
> arch/x86/kernel/alternative.c | 30 +++-
> arch/x86/kernel/module.c | 1 +
> arch/x86/mm/init_64.c | 3 +-
> include/linux/vmalloc.h | 2 +
> kernel/bpf/core.c | 155 ++----------------
> kernel/module/main.c | 23 +--
> kernel/module/strict_rwx.c | 3 -
> kernel/trace/ftrace.c | 3 +-
> mm/nommu.c | 7 +
> mm/vmalloc.c | 296 ++++++++++++++++++++++++++++++++++
> 11 files changed, 358 insertions(+), 166 deletions(-)
>
> --
> 2.30.2
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