commit 027ef6c87853b0a9df53175063028edb4950d476 upstream.

In many places !pmd_present has been converted to pmd_none.  For pmds
that's equivalent and pmd_none is quicker so using pmd_none is better.

However (unless we delete pmd_present) we should provide an accurate
pmd_present too.  This will avoid the risk of code thinking the pmd is non
present because it's under __split_huge_page_map, see the pmd_mknotpresent
there and the comment above it.

If the page has been mprotected as PROT_NONE, it would also lead to a
pmd_present false negative in the same way as the race with
split_huge_page.

Because the PSE bit stays on at all times (both during split_huge_page and
when the _PAGE_PROTNONE bit get set), we could only check for the PSE bit,
but checking the PROTNONE bit too is still good to remember pmd_present
must always keep PROT_NONE into account.

This explains a not reproducible BUG_ON that was seldom reported on the
lists.

The same issue is in pmd_large, it would go wrong with both PROT_NONE and
if it races with split_huge_page.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull Xen bug-fixes from Konrad Rzeszutek Wilk:
 - Fix M2P batching re-using the incorrect structure field.

   In v3.5 we added batching for M2P override (Machine Frame Number ->
   Physical Frame Number), but the original MFN was saved in an
   incorrect structure - and we would oops/restore when restoring with
   the old MFN.

 - Disable BIOS SMP MP table search.

   A bootup issue that we had ignored until we found that on DL380 G6 it
   was needed.

* tag 'stable/for-linus-3.6-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
  xen/boot: Disable BIOS SMP MP table search.
  xen/m2p: do not reuse kmap_op->dev_bus_addr

If the caller passes a valid kmap_op to m2p_add_override, we use
kmap_op->dev_bus_addr to store the original mfn, but dev_bus_addr is
part of the interface with Xen and if we are batching the hypercalls it
might not have been written by the hypervisor yet. That means that later
on Xen will write to it and we'll think that the original mfn is
actually what Xen has written to it.

Rather than "stealing" struct members from kmap_op, keep using
page->index to store the original mfn and add another parameter to
m2p_remove_override to get the corresponding kmap_op instead.
It is now responsibility of the caller to keep track of which kmap_op
corresponds to a particular page in the m2p_override (gntdev, the only
user of this interface that passes a valid kmap_op, is already doing that).

CC: stable@kernel.org
Reported-and-Tested-By: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

This comment is no longer true.  We support up to 2^16 CPUs
because __ticket_t is an u16 if NR_CPUS is larger than 256.

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Pull x86 fixes from Ingo Molnar:
 "Various fixes"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86-64, kcmp: The kcmp system call can be common
  arch/x86/kernel/kdebugfs.c: Ensure a consistent return value in error case
  x86/mce: Add quirk for instruction recovery on Sandy Bridge processors
  x86/mce: Move MCACOD defines from mce-severity.c to <asm/mce.h>
  x86/ioapic: Fix NULL pointer dereference on CPU hotplug after disabling irqs
  x86, nops: Missing break resulting in incorrect selection on Intel
  x86: CONFIG_CC_STACKPROTECTOR=y is no longer experimental

Pull perf fixes from Ingo Molnar:
 "Fix merge window fallout and fix sleep profiling (this was always
  broken, so it's not a fix for the merge window - we can skip this one
  from the head of the tree)."

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/trace: Add ability to set a target task for events
  perf/x86: Fix USER/KERNEL tagging of samples properly
  perf/x86/intel/uncore: Make UNCORE_PMU_HRTIMER_INTERVAL 64-bit

Pull OLPC platform updates from Andres Salomon:
 "These move the OLPC Embedded Controller driver out of
  arch/x86/platform and into drivers/platform/olpc.

  OLPC machines are now ARM-based (which means lots of x86 and ARM
  changes), but are typically pretty self-contained..  so it makes more
  sense to go through a separate OLPC tree after getting the appropriate
  review/ACKs."

* 'for-linus-3.6' of git://dev.laptop.org/users/dilinger/linux-olpc:
  x86: OLPC: move s/r-related EC cmds to EC driver
  Platform: OLPC: move global variables into priv struct
  Platform: OLPC: move debugfs support from x86 EC driver
  x86: OLPC: switch over to using new EC driver on x86
  Platform: OLPC: add a suspended flag to the EC driver
  Platform: OLPC: turn EC driver into a platform_driver
  Platform: OLPC: allow EC cmd to be overridden, and create a workqueue to call it
  drivers: OLPC: update various drivers to include olpc-ec.h
  Platform: OLPC: add a stub to drivers/platform/ for the OLPC EC driver

This uses the new EC driver framework in drivers/platform/olpc.  The
XO-1 and XO-1.5-specific code is still in arch/x86, but the generic stuff
(including a new workqueue; no more running EC commands with IRQs disabled!)
can be shared with other architectures.

Signed-off-by: Andres Salomon <dilinger@queued.net>
Acked-by: Paul Fox <pgf@laptop.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

Switch over to using olpc-ec.h in multiple steps, so as not to break builds.
This covers every driver that calls olpc_ec_cmd().

Signed-off-by: Andres Salomon <dilinger@queued.net>
Acked-by: Paul Fox <pgf@laptop.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

The OLPC EC driver has outgrown arch/x86/platform/.  It's time to both
share common code amongst different architectures, as well as move it out
of arch/x86/.  The XO-1.75 is ARM-based, and the EC driver shares a lot of
code with the x86 code.

Signed-off-by: Andres Salomon <dilinger@queued.net>
Acked-by: Paul Fox <pgf@laptop.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>