linux-kernel - Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls

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Message-ID: <577FFE55.7040209@sr71.net>
Date:	Fri, 8 Jul 2016 12:26:13 -0700
From:	Dave Hansen <dave@...1.net>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Mel Gorman <mgorman@...hsingularity.net>,
	linux-kernel@...r.kernel.org, x86@...nel.org,
	linux-api@...r.kernel.org, linux-arch@...r.kernel.org,
	linux-mm@...ck.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, dave.hansen@...ux.intel.com,
	arnd@...db.de, hughd@...gle.com, viro@...iv.linux.org.uk
Subject: Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls

On 07/08/2016 12:18 AM, Ingo Molnar wrote:
> So my hope was that we'd also grow some debugging features: such as a periodic 
> watchdog timer clearing all non-allocated pkeys of a task and re-setting them to 
> their (kernel-)known values and thus forcing user-space to coordinate key 
> allocation/freeing.

I'm glad you mentioned this.  I've explicitly called out this behavior
in the manpages now, or at least called out the fact that the kernel
will not preserve PKRU contents for unallocated keys.