linux-kernel - Re: [Xen-devel] [PATCH] x86: hold mm->page_table_lock while doing vmalloc

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Message-ID: <4CB88A4C.1080305@goop.org>
Date:	Fri, 15 Oct 2010 10:07:24 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	"Xen-devel@...ts.xensource.com" <Xen-devel@...ts.xensource.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jan Beulich <JBeulich@...ell.com>,
	Ian Campbell <Ian.Campbell@...rix.com>
Subject: Re: [Xen-devel] [PATCH] x86: hold mm->page_table_lock while doing
 vmalloc_sync

 On 10/14/2010 01:56 PM, Jeremy Fitzhardinge wrote:
> Take mm->page_table_lock while syncing the vmalloc region.  This prevents
> a race with the Xen pagetable pin/unpin code, which expects that the
> page_table_lock is already held.  If this race occurs, then Xen can see
> an inconsistent page type (a page can either be read/write or a pagetable
> page, and pin/unpin converts it between them), which will cause either
> the pin or the set_p[gm]d to fail; either will crash the kernel.

I've merged this into tip/x86/mm, which had some conflicting changes
(and fixed up some whitespace issues in one of those changes):

The following changes since commit a416e9e1dde0fbcf20cda59df284cc0dcf2aadc4:

  x86-32: Fix sparse warning for the __PHYSICAL_MASK calculation (2010-10-07 16:36:17 -0700)

are available in the git repository at:
  git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git x86-mm

Jeremy Fitzhardinge (2):
      x86/mm: fix bogus whitespace in sync_global_pgds()
      x86: hold mm->page_table_lock while doing vmalloc_sync

 arch/x86/include/asm/pgtable.h |    2 +
 arch/x86/mm/fault.c            |   11 ++++++++-
 arch/x86/mm/init_64.c          |   51 ++++++++++++++++++++++-----------------
 arch/x86/mm/pgtable.c          |   20 +++++++++++++--
 4 files changed, 58 insertions(+), 26 deletions(-)

	J

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