From: Mel Gorman <mgorman@suse.de>
To: David Vrabel <david.vrabel@citrix.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Cyrill Gorcunov <gorcunov@gmail.com>, Peter Anvin <hpa@zytor.com>,
Ingo Molnar <mingo@kernel.org>,
Steven Noonan <steven@uplinklabs.net>,
Rik van Riel <riel@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Linux-MM <linux-mm@kvack.org>, Linux-X86 <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/3] x86: Define _PAGE_NUMA with unused physical address bits PMD and PTE levels
Date: Mon, 7 Apr 2014 16:49:35 +0100 [thread overview]
Message-ID: <20140407154935.GD7292@suse.de> (raw)
In-Reply-To: <5342C517.2020305@citrix.com>
On Mon, Apr 07, 2014 at 04:32:39PM +0100, David Vrabel wrote:
> On 07/04/14 16:10, Mel Gorman wrote:
> > _PAGE_NUMA is currently an alias of _PROT_PROTNONE to trap NUMA hinting
> > faults. As the bit is shared care is taken that _PAGE_NUMA is only used in
> > places where _PAGE_PROTNONE could not reach but this still causes problems
> > on Xen and conceptually difficult.
>
> The problem with Xen guests occurred because mprotect() /was/ confusing
> PROTNONE mappings with _PAGE_NUMA and clearing the non-existant NUMA hints.
>
I didn't bother spelling it out in case I gave the impression that I was
blaming Xen for the problem. As the bit is now changes, does it help
the Xen problem or cause another collision of some sort? There is no
guarantee _PAGE_NUMA will remain as bit 62 but at worst it'll use bit 11
and NUMA_BALANCING will depend in !KMEMCHECK.
--
Mel Gorman
SUSE Labs
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WARNING: multiple messages have this Message-ID (diff)
From: Mel Gorman <mgorman@suse.de>
To: David Vrabel <david.vrabel@citrix.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Cyrill Gorcunov <gorcunov@gmail.com>, Peter Anvin <hpa@zytor.com>,
Ingo Molnar <mingo@kernel.org>,
Steven Noonan <steven@uplinklabs.net>,
Rik van Riel <riel@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Linux-MM <linux-mm@kvack.org>, Linux-X86 <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/3] x86: Define _PAGE_NUMA with unused physical address bits PMD and PTE levels
Date: Mon, 7 Apr 2014 16:49:35 +0100 [thread overview]
Message-ID: <20140407154935.GD7292@suse.de> (raw)
In-Reply-To: <5342C517.2020305@citrix.com>
On Mon, Apr 07, 2014 at 04:32:39PM +0100, David Vrabel wrote:
> On 07/04/14 16:10, Mel Gorman wrote:
> > _PAGE_NUMA is currently an alias of _PROT_PROTNONE to trap NUMA hinting
> > faults. As the bit is shared care is taken that _PAGE_NUMA is only used in
> > places where _PAGE_PROTNONE could not reach but this still causes problems
> > on Xen and conceptually difficult.
>
> The problem with Xen guests occurred because mprotect() /was/ confusing
> PROTNONE mappings with _PAGE_NUMA and clearing the non-existant NUMA hints.
>
I didn't bother spelling it out in case I gave the impression that I was
blaming Xen for the problem. As the bit is now changes, does it help
the Xen problem or cause another collision of some sort? There is no
guarantee _PAGE_NUMA will remain as bit 62 but at worst it'll use bit 11
and NUMA_BALANCING will depend in !KMEMCHECK.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2014-04-07 15:49 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-07 15:10 [RFC PATCH 0/3] Use an alternative to _PAGE_PROTNONE for _PAGE_NUMA Mel Gorman
2014-04-07 15:10 ` Mel Gorman
2014-04-07 15:10 ` [PATCH 1/3] x86: Require x86-64 for automatic NUMA balancing Mel Gorman
2014-04-07 15:10 ` Mel Gorman
2014-04-07 15:10 ` [PATCH 2/3] x86: Define _PAGE_NUMA with unused physical address bits PMD and PTE levels Mel Gorman
2014-04-07 15:10 ` Mel Gorman
2014-04-07 15:32 ` David Vrabel
2014-04-07 15:32 ` David Vrabel
2014-04-07 15:49 ` Mel Gorman [this message]
2014-04-07 15:49 ` Mel Gorman
2014-04-07 16:19 ` Cyrill Gorcunov
2014-04-07 16:19 ` Cyrill Gorcunov
2014-04-07 18:28 ` Mel Gorman
2014-04-07 18:28 ` Mel Gorman
2014-04-07 19:16 ` Cyrill Gorcunov
2014-04-07 19:16 ` Cyrill Gorcunov
2014-04-07 19:27 ` H. Peter Anvin
2014-04-07 19:27 ` H. Peter Anvin
2014-04-07 19:36 ` Cyrill Gorcunov
2014-04-07 19:36 ` Cyrill Gorcunov
2014-04-07 19:42 ` H. Peter Anvin
2014-04-07 19:42 ` H. Peter Anvin
2014-04-07 21:25 ` Mel Gorman
2014-04-07 21:25 ` Mel Gorman
2014-04-08 4:04 ` Steven Noonan
2014-04-08 4:04 ` Steven Noonan
2014-04-08 15:16 ` H. Peter Anvin
2014-04-08 15:16 ` H. Peter Anvin
2014-04-08 16:02 ` Konrad Rzeszutek Wilk
2014-04-08 16:02 ` Konrad Rzeszutek Wilk
2014-04-08 16:16 ` H. Peter Anvin
2014-04-08 16:16 ` H. Peter Anvin
2014-04-08 16:47 ` Mel Gorman
2014-04-08 16:47 ` Mel Gorman
2014-04-08 16:50 ` David Vrabel
2014-04-08 16:50 ` David Vrabel
2014-04-08 16:51 ` Mel Gorman
2014-04-08 16:51 ` Mel Gorman
2014-04-09 15:18 ` Konrad Rzeszutek Wilk
2014-04-09 15:18 ` Konrad Rzeszutek Wilk
2014-04-09 15:39 ` Mel Gorman
2014-04-09 15:39 ` Mel Gorman
2014-04-08 20:51 ` Steven Noonan
2014-04-08 20:51 ` Steven Noonan
2014-04-08 20:59 ` H. Peter Anvin
2014-04-08 20:59 ` H. Peter Anvin
2014-04-09 15:04 ` Konrad Rzeszutek Wilk
2014-04-09 15:04 ` Konrad Rzeszutek Wilk
2014-04-09 15:09 ` Peter Zijlstra
2014-04-09 15:09 ` Peter Zijlstra
2014-04-08 9:31 ` David Vrabel
2014-04-08 9:31 ` David Vrabel
2014-04-07 21:19 ` Mel Gorman
2014-04-07 21:19 ` Mel Gorman
2014-04-07 17:37 ` Dave Hansen
2014-04-07 17:37 ` Dave Hansen
2014-04-07 15:10 ` [PATCH 3/3] mm: Allow FOLL_NUMA on FOLL_FORCE Mel Gorman
2014-04-07 15:10 ` Mel Gorman
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