linux-kernel - Re: [PATCH] um: Abandon the _PAGE

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Message-ID: <fcaa6038-33dc-44a9-ab23-ac2309eeef4d@antgroup.com>
Date: Fri, 11 Oct 2024 16:53:38 +0800
From: "Tiwei Bie" <tiwei.btw@...group.com>
To: Benjamin Berg <benjamin@...solutions.net>, richard@....at,
 anton.ivanov@...bridgegreys.com, johannes@...solutions.net
Cc: linux-um@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] um: Abandon the _PAGE_NEWPROT bit

Hi,

On 2024/10/11 15:39, Benjamin Berg wrote:
> Hi,
> 
> On Fri, 2024-10-11 at 13:38 +0800, Tiwei Bie wrote:
>> When a PTE is updated in the page table, the _PAGE_NEWPAGE bit will
>> always be set. And the corresponding page will always be mapped or
>> unmapped depending on whether the PTE is present or not. The check
>> on the _PAGE_NEWPROT bit is not really reachable. Abandoning it will
>> allow us to simplify the code and remove the unreachable code.
> 
> Oh, nice cleanup!
> 
> And I like that mprotect is gone as I don't want it in SECCOMP mode :-)
> 
> Maybe we should rename _PAGE_NEWPAGE to something like _PAGE_NEEDSYNC?
> I think that might make it more clear how everything ties together.

Good idea! Will do.

> 
> Anyway, the change looks good to me.
> 
> Benjamin
> 
> Reviewed-by: Benjamin Berg <benjamin.berg@...el.com>

Thanks! :)

Regards,
Tiwei