lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Mon, 7 Apr 2014 20:19:10 +0400
From:	Cyrill Gorcunov <>
To:	Mel Gorman <>
Cc:	David Vrabel <>,
	Linus Torvalds <>,
	Peter Anvin <>, Ingo Molnar <>,
	Steven Noonan <>,
	Rik van Riel <>,
	Andrew Morton <>,
	Peter Zijlstra <>,
	Andrea Arcangeli <>,
	Linux-MM <>, Linux-X86 <>,
	LKML <>,
	Pavel Emelyanov <>
Subject: Re: [PATCH 2/3] x86: Define _PAGE_NUMA with unused physical address
 bits PMD and PTE levels

On Mon, Apr 07, 2014 at 04:49:35PM +0100, Mel Gorman wrote:
> 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.

Fwiw, we're using bit 11 for soft-dirty tracking, so i really hope worst case
never happen. (At the moment I'm trying to figure out if with this set
it would be possible to clean up ugly macros in pgoff_to_pte for 2 level pages).
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists