linux-kernel - Re: [PATCH 01/10] mm: Move common parts of pagetable_*

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Message-ID: <75cb4ff8-eb0c-4519-a30a-f8be717ba278@arm.com>
Date: Fri, 20 Dec 2024 11:49:38 +0100
From: Kevin Brodsky <kevin.brodsky@....com>
To: Peter Zijlstra <peterz@...radead.org>,
 Qi Zheng <zhengqi.arch@...edance.com>
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
 Catalin Marinas <catalin.marinas@....com>,
 Dave Hansen <dave.hansen@...ux.intel.com>,
 Linus Walleij <linus.walleij@...aro.org>, Andy Lutomirski <luto@...nel.org>,
 "Mike Rapoport (IBM)" <rppt@...nel.org>, Ryan Roberts
 <ryan.roberts@....com>, Thomas Gleixner <tglx@...utronix.de>,
 Will Deacon <will@...nel.org>, Matthew Wilcox <willy@...radead.org>,
 linux-alpha@...r.kernel.org, linux-arch@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-csky@...r.kernel.org,
 linux-hexagon@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-m68k@...ts.linux-m68k.org, linux-mips@...r.kernel.org,
 linux-openrisc@...r.kernel.org, linux-parisc@...r.kernel.org,
 linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
 linux-snps-arc@...ts.infradead.org, linux-um@...ts.infradead.org,
 loongarch@...ts.linux.dev, x86@...nel.org,
 Alexander Gordeev <agordeev@...ux.ibm.com>
Subject: Re: [PATCH 01/10] mm: Move common parts of pagetable_*_[cd]tor to
 helpers

Hi Peter, Qi,

On 19/12/2024 18:19, Peter Zijlstra wrote:
> On Thu, Dec 19, 2024 at 04:44:16PM +0000, Kevin Brodsky wrote:
>> Besides the ptlock management at PTE/PMD level, all the
>> pagetable_*_[cd]tor have the same implementation. Introduce common
>> helpers for all levels to reduce the duplication.
> Uff, I forgot to Cc you on the discussion here, sorry!:
>
>   https://lkml.kernel.org/r/cover.1734526570.git.zhengqi.arch@bytedance.com
>
> we now have two series doing more or less overlapping things :/
>
> You can in fact trivially merge the all the implementations -- the
> apparent non-common bit (ptlock_free) is a no-op for all those other
> levels because they'll be having ptdesc->lock == NULL.

Ah that is good to know, thanks for letting me know about that and Qi's
series! Fortunately there isn't that much overlap between our series - I
think we can easily sort this out.

Qi, shall we collaborate to make our series complementary? I believe my
series covers patch 2 and 4 of your series, but it goes further by
covering all levels and all architectures, and patches introducing
ctor/dtor are already split as Alexander suggested on your series. So my
suggestion would be:

* Remove patch 1 in my series - I'd just introduce
pagetable_{p4d,pgd}_[cd]tor with the same implementation as
pagetable_pud_[cd]tor.
* Remove patch 2 and 4 from your series and rebase it on mine.

Let me know if that makes sense, if so I'll post a v2.

Cheers,
- Kevin