linux-kernel - Re: [PATCH 5/8] x86, pkeys: allocation/free syscalls

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Date:	Wed, 1 Jun 2016 17:17:26 -0700
From:	Dave Hansen <dave@...1.net>
To:	mtk.manpages@...il.com
Cc:	Jonathan Corbet <corbet@....net>,
	lkml <linux-kernel@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	Linux API <linux-api@...r.kernel.org>,
	linux-arch <linux-arch@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH 5/8] x86, pkeys: allocation/free syscalls

On 06/01/2016 05:11 PM, Michael Kerrisk (man-pages) wrote:
>>> >>
>>> >> If I read this right, it doesn't actually remove any pkey restrictions
>>> >> that may have been applied while the key was allocated.  So there could be
>>> >> pages with that key assigned that might do surprising things if the key is
>>> >> reallocated for another use later, right?  Is that how the API is intended
>>> >> to work?
>> >
>> > Yeah, that's how it works.
>> >
>> > It's not ideal.  It would be _best_ if we during mm_pkey_free(), we
>> > ensured that no VMAs under that mm have that vma_pkey() set.  But, that
>> > search would be potentially expensive (a walk over all VMAs), or would
>> > force us to keep a data structure with a count of all the VMAs with a
>> > given key.
>> >
>> > I should probably discuss this behavior in the manpages and address it
> s/probably//
> 
> And, did I miss it. Was there an updated man-pages patch in the latest
> series? I did not notice it.

There have been to changes to the patches that warranted updating the
manpages until now.  I'll send the update immediately.