linux-kernel - Re: NUMA_BALANCING and Xen PV guest regression in 3.20-rc0

lists.openwall.net		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 linux-cve-announce 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]

Message-ID: <CA+55aFxay3mZCNxLKtzh+BMEfj_s256+amXEipeGYoTK2KCPTg@mail.gmail.com>
Date:	Thu, 19 Feb 2015 15:09:01 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	David Vrabel <david.vrabel@...rix.com>
Cc:	Mel Gorman <mgorman@...e.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Xen-devel@...ts.xen.org" <Xen-devel@...ts.xen.org>
Subject: Re: NUMA_BALANCING and Xen PV guest regression in 3.20-rc0

On Thu, Feb 19, 2015 at 5:06 AM, David Vrabel <david.vrabel@...rix.com> wrote:
>
> The NUMA_BALANCING series beginning with 5d833062139d (mm: numa: do not
> dereference pmd outside of the lock during NUMA hinting fault) and
> specifically 8a0516ed8b90 (mm: convert p[te|md]_numa users to
> p[te|md]_protnone_numa) breaks Xen 64-bit PV guests.
>
> Any fault on a present userspace mapping (e.g., a write to a read-only
> mapping) is being misinterpreted as a NUMA hinting fault and not handled
> correctly.  All userspace programs end up continuously  faulting.
>
> This is because the hypervisor sets _PAGE_GLOBAL (== _PAGE_PROTNONE) on
> all present userspace page table entries.

That's some crazy stuff, but whatever. The patch is clearly good. Applied,

                     Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/