linux-kernel - Re: [PATCH] mm: add access/dirty bit on numa page fault

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Date:   Wed, 16 Mar 2022 15:12:35 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     maobibo <maobibo@...ngson.cn>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: add access/dirty bit on numa page fault



On 3/16/22 12:33, maobibo wrote:
> 
> On 03/16/2022 02:43 PM, Anshuman Khandual wrote:
>>
>> On 3/16/22 06:38, Bibo Mao wrote:
>>> During numa page fault, dirty bit can be added for old pte if
>>> fail to migrate on write fault. And if it succeeds to migrate,
>>> access bit can be added for migrated new pte, also dirty bit
>>> can be added for write fault.
>> The current code does not set the access and dirty bits when ever
>> applicable i.e on FAULT_FLAG_WRITE, on the pte (old if migration
>> fails, new if migration succeeds) ? Did not this cause any problem
>> earlier ? I am wondering how this might have gone unnoticed.

> On arm/x86 platform hw will set access/dirty bits automatically,
> however on MIPS platform access/dirty bits are set by software in next
> page fault, it is relatively easier to watch on MIPS platform.

Could you please update this in the commit message as well ?