Re: [PATCH] Install kernel-page-flags.h

[Alexey Dobriyan]

On Mon, Mar 19, 2012 at 2:32 PM, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
> On Wed, Mar 14, 2012 at 12:40:36PM +0200, Alexey Dobriyan wrote:
>> >> Programs using /proc/kpageflags need to know about the various flags. ??The
>> >> <linux/kernel-page-flags.h> provides them and the comments in the file
>> >> indicate that it is supposed to be used by user-level code. ??But the file
>> >> is not installed.
>> >>
>> >> The patch below installs the headers and marks the unstable flags as
>> >> out-of-bounds.
>> >
>> > I don't think this is a good idea at all. ??Let's shoot the person who
>> > added that braindead interface ASAP, and replace it with one printing
>> > the flags in ASCII format.
>>
>> ASCII sucks.
>> This interface is not for humans.
>
> But we still can't lock down the page flags for a user interface - they
> are a very scare resource and we can't afford to keep them stable due
> to userspace poking into internals.
>
> I guess the best we can do is to have a translation table for kernel
> internal to external documented flags. ÂOnce you export the header with
> the meanings it's time to add that table, even if it starts out as a 1:1
> mapping.

Well, this is totally different issue.
Translation is already there, see stable_page_flags().
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