Re: [PATCH v2 2/7] fs/proc/page: use a folio in stable_page_flags()

From: Gregory Price <gregory.price@memverge.com>
To: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Matthew Wilcox <willy@infradead.org>,
	David Hildenbrand <david@redhat.com>
Subject: Re: [PATCH v2 2/7] fs/proc/page: use a folio in stable_page_flags()
Date: Fri, 10 Nov 2023 16:50:18 -0500	[thread overview]
Message-ID: <ZU6lmvMpSfKjjYB3@memverge.com> (raw)
In-Reply-To: <20231110033324.2455523-3-wangkefeng.wang@huawei.com>

On Fri, Nov 10, 2023 at 11:33:19AM +0800, Kefeng Wang wrote:
> Replace nine compound_head() calls with one page_folio().
>

Sorry to echo Matthew, but this commit message is extremely
insufficient and just outright wrong.

Single pass through, here's the real change list:

1) changes PageFLAG() calls to folio_test_FLAG calls
2) changes compound_head() flag checks to folio_test_FLAG checks
3) change page count to folio ref count
   -- without even looking... is this even correct? Need more
      explanation here. Is page count === folio ref count?

So there are really 3 changes in this patch set that should be broken
out separately, even if they all depend on folio flags, because they
need separate explanation and validation for correctness.

> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>  fs/proc/page.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 