linux-kernel - Re: [PATCH] mm: Work around Intel SNB GTT bug with some physical pages.

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Message-ID: <CA+55aFyd08=eemQsUFvtjerEVQdznhe647w4PmSrPkkEvjNuzg@mail.gmail.com>
Date:	Tue, 8 May 2012 08:25:38 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Stéphane Marchesin <marcheu@...omium.org>
Cc:	linux-kernel@...r.kernel.org, keithp@...thp.com,
	seanpaul@...omium.org, olofj@...omium.org,
	dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] mm: Work around Intel SNB GTT bug with some physical pages.

On Mon, May 7, 2012 at 4:13 PM, Stéphane Marchesin <marcheu@...omium.org> wrote:
>
> In the end, I came up with the ugly workaround of just leaking the
> offending pages in shmem.c.

Don't leak it.

Instead, add it to some RCU list, and free it using RCU. Or some
one-second timer or something.

That kind of approach should guarantee that it

 (a) gets returned to the system

but

 (b) the returning to the system gets delayed sufficiently that if the
i915 driver is doing lots of allocations it will be getting other
pages.

Hmm?

              Linus
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