From: Linus Torvalds <torvalds@osdl.org>
To: Andrea Arcangeli <andrea@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Andrew Morton <akpm@osdl.org>,
Linux Kernel list <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@elte.hu>, Ben LaHaise <bcrl@kvack.org>,
linux-mm@kvack.org,
Architectures Group <linux-arch@vger.kernel.org>
Subject: Re: [PATCH] ppc64: Fix possible race with set_pte on a present PTE
Date: Mon, 24 May 2004 21:59:36 -0700 (PDT) [thread overview]
Message-ID: <Pine.LNX.4.58.0405242156380.9951@ppc970.osdl.org> (raw)
In-Reply-To: <20040525045059.GW29378@dualathlon.random>
On Tue, 25 May 2004, Andrea Arcangeli wrote:
>
> no, that's not what I remeber from alpha, alpha always sets the young
> bit as soon as it sets the pte from non-null to something.
Yes.
However, whtn the page is _aged_ later, the young bits will be cleared.
And _that_ is when you will now start getting infinite page faults,
because with your patch the young bits will never be set again on a normal
read.
See what I'm saying?
Your patch literally leaves the page table alone on pure reads. Which is
not acceptable, since the page being marked old was what caused the
read-fault in the first place.
But yes, pages will be young by default, so you won't ever actually _see_
this behaviour until you start having memory pressure and VM reclaim
starts trying to age the things.
Linus
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next prev parent reply other threads:[~2004-05-25 4:59 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1085369393.15315.28.camel@gaston>
[not found] ` <Pine.LNX.4.58.0405232046210.25502@ppc970.osdl.org>
[not found] ` <1085371988.15281.38.camel@gaston>
[not found] ` <Pine.LNX.4.58.0405232134480.25502@ppc970.osdl.org>
[not found] ` <1085373839.14969.42.camel@gaston>
2004-05-24 5:10 ` Linus Torvalds
2004-05-24 5:34 ` Benjamin Herrenschmidt
2004-05-24 5:38 ` Benjamin Herrenschmidt
2004-05-24 5:52 ` Benjamin Herrenschmidt
2004-05-24 7:39 ` Ingo Molnar
2004-05-24 5:39 ` Benjamin Herrenschmidt
2004-05-25 3:43 ` Andrea Arcangeli
2004-05-25 4:00 ` Linus Torvalds
2004-05-25 4:17 ` Benjamin Herrenschmidt
2004-05-25 4:37 ` Andrea Arcangeli
2004-05-25 4:40 ` Benjamin Herrenschmidt
2004-05-25 4:20 ` Andrea Arcangeli
2004-05-25 4:39 ` Linus Torvalds
2004-05-25 4:44 ` Linus Torvalds
2004-05-25 4:59 ` Andrea Arcangeli
2004-05-25 5:09 ` Andrea Arcangeli
2004-05-25 4:50 ` Andrea Arcangeli
2004-05-25 4:59 ` Linus Torvalds [this message]
2004-05-25 4:43 ` David Mosberger
2004-05-25 4:53 ` Andrea Arcangeli
2004-05-27 21:56 ` David Mosberger
2004-05-27 22:00 ` Benjamin Herrenschmidt
2004-05-27 22:12 ` David Mosberger
2004-05-25 11:44 ` Matthew Wilcox
2004-05-25 14:48 ` Linus Torvalds
2004-05-25 15:35 ` Keith M Wesolowski
2004-05-25 16:19 ` Linus Torvalds
2004-05-25 17:25 ` David S. Miller
2004-05-25 17:49 ` Linus Torvalds
2004-05-25 17:54 ` David S. Miller
2004-05-25 18:05 ` Linus Torvalds
2004-05-25 20:30 ` Linus Torvalds
2004-05-25 20:35 ` David S. Miller
2004-05-25 20:49 ` Linus Torvalds
2004-05-25 20:57 ` David S. Miller
2004-05-26 6:20 ` Keith M Wesolowski
2004-05-25 21:40 ` Benjamin Herrenschmidt
2004-05-25 21:54 ` Linus Torvalds
2004-05-25 22:00 ` Linus Torvalds
2004-05-25 22:07 ` Benjamin Herrenschmidt
2004-05-25 22:14 ` Linus Torvalds
2004-05-26 0:21 ` Benjamin Herrenschmidt
2004-05-26 0:50 ` Linus Torvalds
2004-05-26 3:25 ` Benjamin Herrenschmidt
2004-05-26 4:08 ` Linus Torvalds
2004-05-26 4:12 ` Benjamin Herrenschmidt
2004-05-26 4:18 ` Benjamin Herrenschmidt
2004-05-26 4:50 ` Linus Torvalds
2004-05-26 4:49 ` Benjamin Herrenschmidt
2004-05-26 4:28 ` Linus Torvalds
2004-05-26 4:46 ` Benjamin Herrenschmidt
2004-05-26 4:54 ` Linus Torvalds
2004-05-26 4:55 ` Benjamin Herrenschmidt
2004-05-26 5:41 ` Benjamin Herrenschmidt
2004-05-26 5:59 ` [PATCH] (signoff) " Benjamin Herrenschmidt
2004-05-26 6:55 ` Benjamin Herrenschmidt
2004-05-25 22:05 ` [PATCH] " Benjamin Herrenschmidt
2004-05-25 22:09 ` Linus Torvalds
2004-05-25 22:19 ` Benjamin Herrenschmidt
2004-05-25 22:24 ` Linus Torvalds
2004-05-25 21:27 ` Andrea Arcangeli
2004-05-25 21:43 ` Linus Torvalds
2004-05-25 21:55 ` Andrea Arcangeli
2004-05-25 22:01 ` Linus Torvalds
2004-05-25 22:18 ` Ivan Kokshaysky
2004-05-25 22:42 ` Andrea Arcangeli
2004-05-26 2:26 ` Linus Torvalds
2004-05-26 7:06 ` Andrea Arcangeli
2004-05-25 21:44 ` Andrea Arcangeli
2004-06-01 12:04 Martin Schwidefsky
2004-06-01 12:10 Martin Schwidefsky
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