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Date:   Thu, 25 Aug 2022 09:22:52 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc:     Jonathan Corbet <corbet@lwn.net>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Shuah Khan <shuah@kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:PROC FILESYSTEM" <linux-fsdevel@vger.kernel.org>,
        "open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>, kernel@collabora.com
Subject: Re: [PATCH v2 2/4] fs/proc/task_mmu: Implement IOCTL to get and
 clear soft dirty PTE bit
Message-ID: <YwcjTOgKD22TXwYk@kroah.com>
References: <20220825070926.2922471-1-usama.anjum@collabora.com>
 <20220825070926.2922471-3-usama.anjum@collabora.com>
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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.

thanks,

greg k-h