linux-kernel - Re: [PATCH v1 3/5] s390/uv: convert PG_arch

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Date: Fri, 5 Apr 2024 04:36:03 +0100
From: Matthew Wilcox <willy@...radead.org>
To: David Hildenbrand <david@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	linux-s390@...r.kernel.org, kvm@...r.kernel.org,
	Heiko Carstens <hca@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	Christian Borntraeger <borntraeger@...ux.ibm.com>,
	Sven Schnelle <svens@...ux.ibm.com>,
	Janosch Frank <frankja@...ux.ibm.com>,
	Claudio Imbrenda <imbrenda@...ux.ibm.com>,
	Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
	Thomas Huth <thuth@...hat.com>
Subject: Re: [PATCH v1 3/5] s390/uv: convert PG_arch_1 users to only work on
 small folios

On Thu, Apr 04, 2024 at 06:36:40PM +0200, David Hildenbrand wrote:
> Now that make_folio_secure() may only set PG_arch_1 for small folios,
> let's convert relevant remaining UV code to only work on (small) folios
> and simply reject large folios early. This way, we'll never end up
> touching PG_arch_1 on tail pages of a large folio in UV code.
> 
> The folio_get()/folio_put() for functions that are documented to already
> hold a folio reference look weird and it should probably be removed.
> Similarly, uv_destroy_owned_page() and uv_convert_owned_from_secure()
> should really consume a folio reference instead. But these are cleanups for
> another day.

Yes, and we should convert arch_make_page_accessible() to
arch_make_folio_accessible() ... one of the two callers already has the
folio (and page-writeback already calls arch_make_folio_accessible()