Re: [GIT PULL] MM updates for 6.13-rc1

[John Hubbard <jhubbard@nvidia.com>]

On 11/22/24 3:23 AM, David Hildenbrand wrote:
> On 22.11.24 06:42, Andrew Morton wrote:
>> On Tue, 19 Nov 2024 04:35:47 +0000 Matthew Wilcox <willy@infradead.org> wrote:
>>
>>> On Mon, Nov 18, 2024 at 07:30:01PM -0800, Andrew Morton wrote:
>>>> Matthew Wilcox (Oracle) (13):
>>>>        ksm: use a folio in try_to_merge_one_page()
>>>>        ksm: convert cmp_and_merge_page() to use a folio
>>>
>>> Unfortunately you left the crap patch in from Gaosheng.  Linus, can you
>>> apply this fixup?
>>>
>>> >From 3d7e7319bbb3ced1dfb9c82bb7e8c7386380799b Mon Sep 17 00:00:00 2001
>>> From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
>>> Date: Mon, 18 Nov 2024 23:32:25 -0500
>>> Subject: [PATCH] mm: Revert IS_ERR_OR_NULL check
>>>
>>> &foo->bar is address arithmetic, not a dereference of foo.
>>> Huawei engineers seem particularly prone to not knowing this.
>>
>> It isn't only Huawai people.  David acked Gaosheng's patch and it snuck
>> past me (again).  People keep on getting tricked by this idiom and I
>> think we'd be better off with some nicely named wrapper to help
>> readers understand what's going on.
> 
> The helper we have is "folio_page(folio, 0)" ... and we do have a bunch of that usage in the kernel.
> 
> Likely we, want a more catchy helper that simply gives us the first (and for small folios the only) page.
> 
> ... not able to come up with good names though. folio_page0(), folio_first_page(), ... :(

Eh? You're doing great at coming up with good names, IMHO. Either of the
above would work nicely!

I'll put my vote in for folio_page0(), it's concise and yet crystal clear.


thanks,
-- 
John Hubbard