linux-kernel - Re: [PATCH 0/4] apply page shift to PFN instead of VA in pfn_to

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Date: Fri, 02 Feb 2024 08:04:34 +0100
From: "Arnd Bergmann" <arnd@...db.de>
To: "Yan Zhao" <yan.y.zhao@...el.com>
Cc: "Linus Walleij" <linus.walleij@...aro.org>, guoren <guoren@...nel.org>,
 "Brian Cain" <bcain@...cinc.com>, "Jonas Bonn" <jonas@...thpole.se>,
 "Stefan Kristiansson" <stefan.kristiansson@...nalahti.fi>,
 "Stafford Horne" <shorne@...il.com>, Linux-Arch <linux-arch@...r.kernel.org>,
 linux-kernel@...r.kernel.org,
 "linux-csky@...r.kernel.org" <linux-csky@...r.kernel.org>,
 linux-hexagon@...r.kernel.org,
 "linux-openrisc@...r.kernel.org" <linux-openrisc@...r.kernel.org>
Subject: Re: [PATCH 0/4] apply page shift to PFN instead of VA in pfn_to_virt

On Fri, Feb 2, 2024, at 02:02, Yan Zhao wrote:
> On Thu, Feb 01, 2024 at 06:46:46AM +0100, Arnd Bergmann wrote:
>> 
>> I think it's fair to assume we won't need asm-generic/page.h any
>> more, as we likely won't be adding new NOMMU architectures.
>> I can have a look myself at removing any such unused headers in
>> include/asm-generic/, it's probably not the only one.
>> 
>> Can you just send a patch to remove the unused pfn_to_virt()
>> functions?
> Ok. I'll do it!
> BTW: do you think it's also good to keep this fixing series though we'll
> remove the unused function later?
> So if people want to revert the removal some day, they can get right one.
>
> Or maybe I'm just paranoid, and explanation about the fix in the commit
> message of patch for function removal is enough.
>
> What's your preference? :)

I would just remove it, there is no point in having both
pfn_to_kaddr() and pfn_to_virt() when they do the exact
same thing aside from this bug.

Just do a single patch for all architectures, no need to
have three or four identical ones when I'm going to merge
them all through the same tree anyway.

Just make sure you explain in the changelog what the bug was
and how you noticed it, in case anyone is ever tempted to
bring the function back.

    Arnd