linux-kernel - Re: [PATCH RFC 0/4] mm: percpu: Cleanup percpu first chunk funciton

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Message-ID: <617f11ad-3033-473f-162e-cb7ecd67a78a@huawei.com>
Date:   Tue, 30 Nov 2021 14:53:33 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Dennis Zhou <dennis@...nel.org>
CC:     <akpm@...ux-foundation.org>, <linux-kernel@...r.kernel.org>,
        <linux-mm@...ck.org>, <tj@...nel.org>,
        <gregkh@...uxfoundation.org>, <cl@...ux.com>,
        <catalin.marinas@....com>, <will@...nel.org>,
        <tsbogend@...ha.franken.de>, <mpe@...erman.id.au>,
        <benh@...nel.crashing.org>, <paulus@...ba.org>,
        <paul.walmsley@...ive.com>, <palmer@...belt.com>,
        <aou@...s.berkeley.edu>, <davem@...emloft.net>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
        <dave.hansen@...ux.intel.com>, <hpa@...or.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-ia64@...r.kernel.org>, <linux-mips@...r.kernel.org>,
        <linuxppc-dev@...ts.ozlabs.org>, <linux-riscv@...ts.infradead.org>,
        <sparclinux@...r.kernel.org>, <x86@...nel.org>
Subject: Re: [PATCH RFC 0/4] mm: percpu: Cleanup percpu first chunk funciton


On 2021/11/30 6:55, Dennis Zhou wrote:
> Hello,
>
> On Sun, Nov 21, 2021 at 05:35:53PM +0800, Kefeng Wang wrote:
>> When support page mapping percpu first chunk allocator on arm64, we
>> found there are lots of duplicated codes in percpu embed/page first
>> chunk allocator. This patchset is aimed to cleanup them and should
>> no funciton change, only test on arm64.
>>
>> Kefeng Wang (4):
>>    mm: percpu: Generalize percpu related config
>>    mm: percpu: Add pcpu_fc_cpu_to_node_fn_t typedef
>>    mm: percpu: Add generic pcpu_fc_alloc/free funciton
>>    mm: percpu: Add generic pcpu_populate_pte() function
>>
>>   arch/arm64/Kconfig             |  20 +----
>>   arch/ia64/Kconfig              |   9 +--
>>   arch/mips/Kconfig              |  10 +--
>>   arch/mips/mm/init.c            |  14 +---
>>   arch/powerpc/Kconfig           |  17 +---
>>   arch/powerpc/kernel/setup_64.c |  92 +--------------------
>>   arch/riscv/Kconfig             |  10 +--
>>   arch/sparc/Kconfig             |  12 +--
>>   arch/sparc/kernel/smp_64.c     | 105 +-----------------------
>>   arch/x86/Kconfig               |  17 +---
>>   arch/x86/kernel/setup_percpu.c |  66 ++-------------
>>   drivers/base/arch_numa.c       |  68 +---------------
>>   include/linux/percpu.h         |  13 +--
>>   mm/Kconfig                     |  12 +++
>>   mm/percpu.c                    | 143 +++++++++++++++++++++++++--------
>>   15 files changed, 165 insertions(+), 443 deletions(-)
>>
>> -- 
>> 2.26.2
>>
> I've made a few comments. I think this will be a little bit of a
> challenge to get through due to it touching so many architectures. For
> ease, it probably makes sense to run it through mny tree, but we'll need
> explicit acks as I mentioned.
>
> I like getting rid of the pcpu_alloc_bootmem()/pcpu_free_bootmem()
> functions. However, let's keep the implementation identical to x86.
ok , will change patch3 in v2
>
>
> I don't think we should get rid of the populate_pte_fn(). I'm not
> comfortable changing x86's implementation. Simply offer a NULL, and if
> NULL use the default.

As replied in patch4, we use __weak method, and x86's implementation is

not changed in patch4, is this ok?

>
> Do you have a tree that intel pulls? I suggest cleaning up the patches
> and pushing to a remote branch that they pick up. That would have caught
> the mips typo. Send a PR creating a file in [1] for your branch, github
> is fine. Basic validation needs to be done before I can pick this up
> too on more than arm64.

Ok, x86/arm64/riscv are tested, but I don't has ppc/mips/sparc compliler.

I will try to push new version into github and test by lkp.

Thanks.

>
> [1] https://github.com/intel/lkp-tests/tree/master/repo/linux
>
> Thanks,
> Dennis
> .