From: "David Hildenbrand (Arm)" <david@kernel•org>
To: Mike Rapoport <rppt@kernel•org>,
Andrew Morton <akpm@linux-foundation•org>
Cc: Andreas Larsson <andreas@gaisler•com>,
Borislav Petkov <bp@alien8•de>, Brian Cain <bcain@kernel•org>,
Catalin Marinas <catalin.marinas@arm•com>,
"Christophe Leroy (CS GROUP)" <chleroy@kernel•org>,
"David S. Miller" <davem@davemloft•net>,
Dave Hansen <dave.hansen@linux•intel.com>,
Dinh Nguyen <dinguyen@kernel•org>,
Geert Uytterhoeven <geert@linux-m68k•org>,
Guo Ren <guoren@kernel•org>, Helge Deller <deller@gmx•de>,
Huacai Chen <chenhuacai@kernel•org>,
Ingo Molnar <mingo@redhat•com>,
Johannes Berg <johannes@sipsolutions•net>,
John Paul Adrian Glaubitz <glaubitz@physik•fu-berlin.de>,
"Liam R. Howlett" <Liam.Howlett@oracle•com>,
Lorenzo Stoakes <lorenzo.stoakes@oracle•com>,
Madhavan Srinivasan <maddy@linux•ibm.com>,
Magnus Lindholm <linmag7@gmail•com>,
Matt Turner <mattst88@gmail•com>,
Max Filippov <jcmvbkbc@gmail•com>,
Michael Ellerman <mpe@ellerman•id.au>,
Michal Hocko <mhocko@suse•com>, Michal Simek <monstr@monstr•eu>,
Palmer Dabbelt <palmer@dabbelt•com>,
Richard Weinberger <richard@nod•at>,
Russell King <linux@armlinux•org.uk>,
Stafford Horne <shorne@gmail•com>,
Suren Baghdasaryan <surenb@google•com>,
Thomas Gleixner <tglx@kernel•org>,
Vineet Gupta <vgupta@kernel•org>,
Vlastimil Babka <vbabka@suse•cz>, Will Deacon <will@kernel•org>,
linux-alpha@vger•kernel.org, linux-kernel@vger•kernel.org,
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linux-m68k@lists•linux-m68k.org, linux-openrisc@vger•kernel.org,
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linux-mm@kvack•org, x86@kernel•org
Subject: Re: [PATCH v2 3/4] arch, mm: consolidate empty_zero_page
Date: Mon, 23 Feb 2026 17:18:24 +0100 [thread overview]
Message-ID: <c5db6944-37fc-401e-bd06-68140f59c6e7@kernel.org> (raw)
In-Reply-To: <20260209144058.2092871-4-rppt@kernel.org>
On 2/9/26 15:40, Mike Rapoport wrote:
> From: "Mike Rapoport (Microsoft)" <rppt@kernel•org>
>
> Reduce 22 declarations of empty_zero_page to 3 and 23 declarations of
> ZERO_PAGE() to 4.
>
> Every architecture defines empty_zero_page that way or another, but for the
> most of them it is always a page aligned page in BSS and most definitions
> of ZERO_PAGE do virt_to_page(empty_zero_page).
>
> Move Linus vetted x86 definition of empty_zero_page and ZERO_PAGE() to the
> core MM and drop these definitions in architectures that do not implement
> colored zero page (MIPS and s390).
>
> ZERO_PAGE() remains a macro because turning it to a wrapper for a static
> inline causes severe pain in header dependencies.
>
> For the most part the change is mechanical, with these being noteworthy:
>
> * alpha: aliased empty_zero_page with ZERO_PGE that was also used for boot
> parameters. Switching to a generic empty_zero_page removes the aliasing
> and keeps ZERO_PGE for boot parameters only
> * arm64: uses __pa_symbol() in ZERO_PAGE() so that definition of
> ZERO_PAGE() is kept intact.
> * m68k/parisc/um: allocated empty_zero_page from memblock,
> although they do not support zero page coloring and having it in BSS
> will work fine.
> * sparc64 can have empty_zero_page in BSS rather allocate it, but it
> can't use virt_to_page() for BSS. Keep it's definition of ZERO_PAGE()
> but instead of allocating it, make mem_map_zero point to
> empty_zero_page.
> * sh: used empty_zero_page for boot parameters at the very early boot.
> Rename the parameters page to boot_params_page and let sh use the generic
> empty_zero_page.
> * hexagon: had an amusing comment about empty_zero_page
>
> /* A handy thing to have if one has the RAM. Declared in head.S */
>
> that unfortunately had to go :)
>
> Acked-by: Helge Deller <deller@gmx•de> # parisc
> Tested-by: Helge Deller <deller@gmx•de> # parisc
> Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel•org>
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel•org>
> ---
Acked-by: David Hildenbrand (Arm) <david@kernel•org>
--
Cheers,
David
next prev parent reply other threads:[~2026-02-23 16:18 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-09 14:40 [PATCH v2 0/4] arch, mm: consolidate empty_zero_page Mike Rapoport
2026-02-09 14:40 ` [PATCH v2 1/4] mm: don't special case !MMU for is_zero_pfn() and my_zero_pfn() Mike Rapoport
2026-02-23 16:16 ` David Hildenbrand (Arm)
2026-02-09 14:40 ` [PATCH v2 2/4] mm: rename my_zero_pfn() to zero_pfn() Mike Rapoport
2026-02-09 15:08 ` Christophe Leroy (CS GROUP)
2026-02-10 14:50 ` Mike Rapoport
2026-02-10 14:52 ` Lorenzo Stoakes
2026-02-10 15:11 ` Mike Rapoport
2026-02-09 14:40 ` [PATCH v2 3/4] arch, mm: consolidate empty_zero_page Mike Rapoport
2026-02-09 15:20 ` Dave Hansen
2026-02-10 15:00 ` Catalin Marinas
2026-02-23 16:18 ` David Hildenbrand (Arm) [this message]
2026-02-09 14:40 ` [PATCH v2 4/4] mm: cache struct page for empty_zero_page and return it from ZERO_PAGE() Mike Rapoport
2026-02-10 15:06 ` Catalin Marinas
2026-02-23 16:20 ` David Hildenbrand (Arm)
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