linux-kernel - Re: [PATCH 2/3] x86/devmem: remove phys_mem_access_prot

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Message-ID: <682e4ed6ec16_1626e1004e@dwillia2-xfh.jf.intel.com.notmuch>
Date: Wed, 21 May 2025 15:08:22 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: Arnd Bergmann <arnd@...nel.org>, Dave Hansen
	<dave.hansen@...ux.intel.com>, Dan Williams <dan.j.williams@...el.com>
CC: Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>, <x86@...nel.org>, Greg Kroah-Hartman
	<gregkh@...uxfoundation.org>, Nikolay Borisov <nik.borisov@...e.com>,
	<linux-kernel@...r.kernel.org>, Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH 2/3] x86/devmem: remove phys_mem_access_prot_allowed()

Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> phys_mem_access_prot_allowed() was originally a workaround for
> certain 32-bit CPUs, but after commit 1886297ce0c8 ("x86/mm/pat:
> Fix BUG_ON() in mmap_mem() on QEMU/i386"), it no longer does anything
> special as the only remaining bit now is the same logic that follows in
> phys_mem_access_prot(), mapping everything as normal memory except when
> either O_DSYNC is set or the address is highmem.
> 
> Just remove the thing entirely.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  arch/x86/mm/pat/memtype.c | 15 ---------------
>  drivers/char/mem.c        | 10 ----------
>  include/linux/pgtable.h   |  2 --
>  3 files changed, 27 deletions(-)

Agree, I came to the same conclusion in the commit message of
1b3f2bd04d90, but then failed to circle back and remove the thing. So,

Reviewed-by: Dan Williams <dan.j.williams@...el.com>