linux-kernel - 答复: [PATCH] arm64: mm: free unused memmap for sparse memory model that define VMEMMAP

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Message-ID: <1699CE87DE933F49876AD744B5DC140F2312A02B@dggemm526-mbx.china.huawei.com>
Date:   Tue, 21 Jul 2020 01:56:33 +0000
From:   "liwei (CM)" <liwei213@...wei.com>
To:     "Song Bao Hua (Barry Song)" <song.bao.hua@...ilicon.com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will@...nel.org" <will@...nel.org>
CC:     fengbaopeng <fengbaopeng2@...ilicon.com>,
        "nsaenzjulienne@...e.de" <nsaenzjulienne@...e.de>,
        "steve.capper@....com" <steve.capper@....com>,
        "rppt@...ux.ibm.com" <rppt@...ux.ibm.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        sujunfei <sujunfei2@...ilicon.com>,
        "Xiaqing (A)" <saberlily.xia@...ilicon.com>,
        "Yaobaofeng (Yaobaofeng)" <yaobaofeng@...wei.com>
Subject: 答复: [PATCH] arm64: mm: free unused memmap for sparse memory model that define VMEMMAP

Hi, all

I'm sorry to bother you, but still very hope you can give comments or suggestions to this patch, thank you very much.


-----邮件原件-----
发件人: Song Bao Hua (Barry Song) 
发送时间: 2020年7月9日 20:27
收件人: liwei (CM) <liwei213@...wei.com>; catalin.marinas@....com; will@...nel.org
抄送: fengbaopeng <fengbaopeng2@...ilicon.com>; nsaenzjulienne@...e.de; steve.capper@....com; rppt@...ux.ibm.com; linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org; sujunfei <sujunfei2@...ilicon.com>; Xiaqing (A) <saberlily.xia@...ilicon.com>; Yaobaofeng (Yaobaofeng) <yaobaofeng@...wei.com>
主题: RE: [PATCH] arm64: mm: free unused memmap for sparse memory model that define VMEMMAP



> -----Original Message-----
> From: liwei (CM)
> Sent: Wednesday, July 8, 2020 7:52 PM
> To: Song Bao Hua (Barry Song) <song.bao.hua@...ilicon.com>; 
> catalin.marinas@....com; will@...nel.org
> Cc: fengbaopeng <fengbaopeng2@...ilicon.com>; nsaenzjulienne@...e.de; 
> steve.capper@....com; rppt@...ux.ibm.com; 
> linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org; 
> sujunfei <sujunfei2@...ilicon.com>; Xiaqing (A) 
> <saberlily.xia@...ilicon.com>; Yaobaofeng (Yaobaofeng) 
> <yaobaofeng@...wei.com>
> Subject: 答复: [PATCH] arm64: mm: free unused memmap for sparse memory 
> model that define VMEMMAP
> 
> Hi, baohua
> 
> Thank you for your attention.
> 
> In my understanding of the MEMORY_HOTPLUG this patch has no effect on it.
> The reason is that in sparse_add_one_section() the memory that memmap 
> needs from Slab if kernel start completed，this memory has nothing to 
> do with memblock alloc/ free memory in the process of kernel start.
> 
> You may have a look vmemmap_alloc_block () this function.
> 
> If I don't understand right welcome pointed out in a timely manner.

At the first glance of this patch, I suspect that this bootmem may be used by hot-added memory.
If you confirm this won't happen, please ignore my noise.

BTW, next time, bear in mind that top-post is not a good way to reply mail :-)

> 
> Thanks!
> 
> 
> -----邮件原件-----
> 发件人: Song Bao Hua (Barry Song)
> 发送时间: 2020年7月8日 15:19
> 收件人: liwei (CM) <liwei213@...wei.com>; catalin.marinas@....com; 
> will@...nel.org
> 抄送: fengbaopeng <fengbaopeng2@...ilicon.com>; nsaenzjulienne@...e.de; 
> steve.capper@....com; rppt@...ux.ibm.com; 
> linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org; 
> sujunfei <sujunfei2@...ilicon.com>
> 主题: RE: [PATCH] arm64: mm: free unused memmap for sparse memory model 
> that define VMEMMAP
> 
> 
> 
> > -----Original Message-----
> > From: liwei (CM)
> > Sent: Wednesday, July 8, 2020 1:56 PM
> > To: catalin.marinas@....com; will@...nel.org
> > Cc: liwei (CM) <liwei213@...wei.com>; fengbaopeng 
> > <fengbaopeng2@...ilicon.com>; nsaenzjulienne@...e.de; 
> > steve.capper@....com; rppt@...ux.ibm.com; Song Bao Hua (Barry Song) 
> > <song.bao.hua@...ilicon.com>; linux-arm-kernel@...ts.infradead.org;
> > linux-kernel@...r.kernel.org; sujunfei <sujunfei2@...ilicon.com>
> > Subject: [PATCH] arm64: mm: free unused memmap for sparse memory
> model
> > that define VMEMMAP
> >
> > For the memory hole, sparse memory model that define
> SPARSEMEM_VMEMMAP
> > do not free the reserved memory for the page map, this patch do it.
> 
> Hello Wei,
> Just curious if this patch breaks MEMORY_HOTPLUG?
> 
> >
> > Signed-off-by: Wei Li <liwei213@...wei.com>
> > Signed-off-by: Chen Feng <puck.chen@...ilicon.com>
> > Signed-off-by: Xia Qing <saberlily.xia@...ilicon.com>
> > ---
> >  arch/arm64/mm/init.c | 81
> > +++++++++++++++++++++++++++++++++++++++++++++-------
> >  1 file changed, 71 insertions(+), 10 deletions(-)
> >
> > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 
> > 1e93cfc7c47a..d1b56b47d5ba 100644
> > --- a/arch/arm64/mm/init.c
> > +++ b/arch/arm64/mm/init.c
> > @@ -441,7 +441,48 @@ void __init bootmem_init(void)
> >  	memblock_dump_all();
> >  }
> >
> 
> Thanks
> Barry