linux-kernel - Re: [PATCH v2 2/4] fs/proc/task_mmu: Implement IOCTL to get and clear soft dirty PTE bit

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Message-ID: <1bfb71e6-1553-b83d-b151-8c8c5ffc5066@collabora.com>
Date:   Thu, 25 Aug 2022 15:49:36 +0500
From:   Muhammad Usama Anjum <usama.anjum@...labora.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     usama.anjum@...labora.com, Jonathan Corbet <corbet@....net>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Shuah Khan <shuah@...nel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:PROC FILESYSTEM" <linux-fsdevel@...r.kernel.org>,
        "open list:MEMORY MANAGEMENT" <linux-mm@...ck.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>, kernel@...labora.com
Subject: Re: [PATCH v2 2/4] fs/proc/task_mmu: Implement IOCTL to get and clear
 soft dirty PTE bit

On 8/25/22 12:22 PM, Greg KH wrote:
> On Thu, Aug 25, 2022 at 12:09:24PM +0500, Muhammad Usama Anjum wrote:
>> - The flags can be specified in the flags field. Currently only one
>>   PAGEMAP_SD_NO_REUSED_REGIONS is supported which can be specified to
>>   ignore the VMA dirty flags.
> 
> You forgot to check that all other bits in that flag are set to 0
> properly, otherwise you can never add a new bit to the field ever as you
> can't expect userspace got it right and did not accidentaly set it
> already.
> 
> There is kernel documentation on how to add a new ioctl, you might want
> to read up on that first before resending this.
Thank you so much for the review. I'll revisit and resend a v3.

> 
> thanks,
> 
> greg k-h

-- 
Muhammad Usama Anjum