Received-SPF: pass (google.com: domain of linux-kernel+bounces-210416-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Date: Tue, 11 Jun 2024 11:21:31 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Andrew Bresticker <abrestic@rivosinc.com>, David Hildenbrand
 <david@redhat.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] mm/memory: Don't require head page for do_set_pmd()
Message-Id: <20240611112131.25925b8ee5198668b88de35f@linux-foundation.org>
In-Reply-To: <ZmiRcUYxrZ5NQQX8@casper.infradead.org>
References: <20240611153216.2794513-1-abrestic@rivosinc.com>
	<ZmiRcUYxrZ5NQQX8@casper.infradead.org>
Precedence: bulk
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit

On Tue, 11 Jun 2024 19:03:29 +0100 Matthew Wilcox <willy@infradead.org> wrote:

> On Tue, Jun 11, 2024 at 08:32:16AM -0700, Andrew Bresticker wrote:
> > -	if (page != &folio->page || folio_order(folio) != HPAGE_PMD_ORDER)
> > +	if (folio_order(folio) != HPAGE_PMD_ORDER)
> >  		return ret;
> > +	page = &folio->page;
> 
> This works today, but in about six months time it's going to be a pain.
> 
> +	page = folio_page(folio, 0);
> 
> is the one which works today and in the future.

I was wondering about that.

hp2:/usr/src/25> fgrep "&folio->page" mm/*.c | wc -l
84
hp2:/usr/src/25> fgrep "folio_page(" mm/*.c | wc -l 
35

Should these all be converted?  What's the general rule here?