linux-kernel - Re: [mm-unstable v3 PATCH 0/7] Cleanup transhuge

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Date:   Thu, 9 Jun 2022 16:32:10 -0700
From:   "Zach O'Keefe" <zokeefe@...gle.com>
To:     Yang Shi <shy828301@...il.com>
Cc:     vbabka@...e.cz, kirill.shutemov@...ux.intel.com,
        willy@...radead.org, akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [mm-unstable v3 PATCH 0/7] Cleanup transhuge_xxx helpers

On Mon, Jun 6, 2022 at 2:44 PM Yang Shi <shy828301@...il.com> wrote:
>
>
> v3: * Fixed the comment from Willy
> v2: * Rebased to the latest mm-unstable
>     * Fixed potential regression for smaps's THPeligible
>
> This series is the follow-up of the discussion about cleaning up transhuge_xxx
> helpers at https://lore.kernel.org/linux-mm/627a71f8-e879-69a5-ceb3-fc8d29d2f7f1@suse.cz/.
>
> THP has a bunch of helpers that do VMA sanity check for different paths, they
> do the similar checks for the most callsites and have a lot duplicate codes.
> And it is confusing what helpers should be used at what conditions.
>
> This series reorganized and cleaned up the code so that we could consolidate
> all the checks into hugepage_vma_check().

By the way, thanks for doing this work. I know I personally was quite
confused about which vma checking function does what / which I should
be using. I briefly tried sketching out how to do something like this
as well - but the various corner cases where e.g. hugepage_vma_check()
and transparent_hugepage_active() differed got confusing. Thanks for
figuring this all out.

> The transhuge_vma_enabled(), transparent_hugepage_active() and
> __transparent_hugepage_enabled() are killed by this series.
>
> Added transhuge_vma_size_ok() helper to remove some duplicate code.
>
>
> Yang Shi (7):
>       mm: khugepaged: check THP flag in hugepage_vma_check()
>       mm: thp: introduce transhuge_vma_size_ok() helper
>       mm: khugepaged: remove the redundant anon vma check
>       mm: khugepaged: use transhuge_vma_suitable replace open-code
>       mm: thp: kill transparent_hugepage_active()
>       mm: thp: kill __transhuge_page_enabled()
>       mm: khugepaged: reorg some khugepaged helpers
>
>  fs/proc/task_mmu.c         |  2 +-
>  include/linux/huge_mm.h    | 84 ++++++++++++++++++++++++++++------------------------------------------
>  include/linux/khugepaged.h | 21 ++----------------
>  mm/huge_memory.c           | 64 +++++++++++++++++++++++++++++++++++++++++++++--------
>  mm/khugepaged.c            | 78 +++++++++++++++--------------------------------------------------
>  mm/memory.c                |  7 ++++--
>  6 files changed, 114 insertions(+), 142 deletions(-)
>
>
>