linux-kernel - Re: [PATCH 0/3] Add PUD and kernel PTE level pagetable account

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Date:   Thu, 7 Jul 2022 19:32:44 +0800
From:   Baolin Wang <baolin.wang@...ux.alibaba.com>
To:     Dave Hansen <dave.hansen@...el.com>, akpm@...ux-foundation.org
Cc:     rppt@...ux.ibm.com, willy@...radead.org, will@...nel.org,
        aneesh.kumar@...ux.ibm.com, npiggin@...il.com,
        peterz@...radead.org, catalin.marinas@....com,
        chenhuacai@...nel.org, kernel@...0n.name,
        tsbogend@...ha.franken.de, dave.hansen@...ux.intel.com,
        luto@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, hpa@...or.com, arnd@...db.de, guoren@...nel.org,
        monstr@...str.eu, jonas@...thpole.se,
        stefan.kristiansson@...nalahti.fi, shorne@...il.com,
        x86@...nel.org, linux-arch@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, loongarch@...ts.linux.dev,
        linux-mips@...r.kernel.org, linux-csky@...r.kernel.org,
        openrisc@...ts.librecores.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/3] Add PUD and kernel PTE level pagetable account



On 7/6/2022 11:48 PM, Dave Hansen wrote:
> On 7/6/22 01:59, Baolin Wang wrote:
>> Now we will miss to account the PUD level pagetable and kernel PTE level
>> pagetable, as well as missing to set the PG_table flags for these pagetable
>> pages, which will get an inaccurate pagetable accounting, and miss
>> PageTable() validation in some cases. So this patch set introduces new
>> helpers to help to account PUD and kernel PTE pagetable pages.
> 
> Could you explain the motivation for this series a bit more?  Is there a
> real-world problem that this fixes?

Not fix real problem. The motivation is that making the pagetable 
accounting more accurate, which helps us to analyse the consumption of 
the pagetable pages in some cases, and maybe help to do some empty 
pagetable reclaiming in future.