Add Bryan Wu as the primary maintainer for drivers/leds
Signed-off-by: NBryan Wu <bryan.wu@canonical.com>
Acked-by: NRichard Purdie <richard.purdie@linuxfoundation.org>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Systems with 8 TBytes of memory or greater can hit a problem where only
the the first 8 TB of memory shows up.  This is due to "int i" being
smaller than "unsigned long start_aligned", causing the high bits to be
dropped.

The fix is to change `i' to unsigned long to match start_aligned
and end_aligned.

Thanks to Jack Steiner for assistance tracking this down.
Signed-off-by: NRuss Anderson <rja@sgi.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Gavin Shan <shangw@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

__devexit functions are discarded without CONFIG_HOTPLUG, so they need
to be referenced carefully.  A __devexit function may also not be called
from a __devinit function.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NMathieu Poirier <mathieu.poirier@linaro.org>
Cc: Bryan Wu <bryan.wu@canonical.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When the last event is unregistered, there is no need to keep the spare
array anymore.  So free it to avoid memory leak.
Signed-off-by: NSha Zhengju <handai.szj@taobao.com>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: NKirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fork() failure post namespace creation for a child cloned with
CLONE_NEWPID leaks pid_namespace/mnt_cache due to proc being mounted
during creation, but not unmounted during cleanup.  Call
pid_ns_release_proc() during cleanup.
Signed-off-by: NMike Galbraith <efault@gmx.de>
Acked-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Louis Rilling <louis.rilling@kerlabs.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit 66aebce7 ("hugetlb: fix race condition in hugetlb_fault()")
added code to avoid a race condition by elevating the page refcount in
hugetlb_fault() while calling hugetlb_cow().

However, one code path in hugetlb_cow() includes an assertion that the
page count is 1, whereas it may now also have the value 2 in this path.

The consensus is that this BUG_ON has served its purpose, so rather than
extending it to cover both cases, we just remove it.
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Acked-by: NHillf Danton <dhillf@gmail.com>
Acked-by: NHugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: <stable@vger.kernel.org>	[3.0.29+, 3.2.16+, 3.3.3+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

percpu_pagelist_fraction_sysctl_handler() has only considered -EINVAL as
a possible error from proc_dointvec_minmax().

If any other error is returned, it would proceed to divide by zero since
percpu_pagelist_fraction wasn't getting initialized at any point.  For
example, writing 0 bytes into the proc file would trigger the issue.
Signed-off-by: NSasha Levin <levinsasha928@gmail.com>
Reviewed-by: NMinchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Reset the current pagemap-entry if the current pte isn't present, or if
current vma is over.  Otherwise pagemap reports last entry again and
again.

Non-present pte reporting was broken in commit 092b50ba ("pagemap:
introduce data structure for pagemap entry")

Reporting for holes was broken in commit 5aaabe83 ("pagemap: avoid
splitting thp when reading /proc/pid/pagemap")
Signed-off-by: NKonstantin Khlebnikov <khlebnikov@openvz.org>
Reported-by: NPavel Emelyanov <xemul@parallels.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Pull a NFS client bugfix from Trond Myklebust:
 "Fix for the NFSv4 security negotiation: ensure that the security
  negotiation tries all registered security flavours"

* tag 'nfs-for-3.4-5' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  auth_gss: the list of pseudoflavors not being parsed correctly

Pull sound fixes from Takashi Iwai:
 "Slightly more than expected as rc7, but all are reasonablly small
  fixes.  A few additions of HD-audio fixup entries, a couple of other
  regression fixes including a revert, and a few other trivial
  oneliners."

* tag 'sound-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ASoC: sh: fix migor.c compilation
  ALSA: HDA: Lessen CPU usage when waiting for chip to respond
  Revert "ALSA: hda - Set codec to D3 forcibly even if not used"
  ALSA: hda/realtek - Call alc_auto_parse_customize_define() always after fixup
  ALSA: hdsp - Provide ioctl_compat
  ALSA: hda/realtek - Add missing CD-input pin for MSI-7350 mobo
  ALSA: hda/realtek - Add a fixup for Acer Aspire 5739G
  ALSA: echoaudio: Remove incorrect part of assertion

compat_sys_sigprocmask reads a smaller signal mask from userspace than
sigprogmask accepts for setting.  So the high word of blocked.sig[0]
will be cleared, releasing any potentially blocked RT signal.

This was discovered via userspace code that relies on get/setcontext.
glibc's i386 versions of those functions use sigprogmask instead of
rt_sigprogmask to save/restore signal mask and caused RT signal
unblocking this way.

As suggested by Linus, this replaces the sys_sigprocmask based compat
version with one that open-codes the required logic, including the merge
of the existing blocked set with the new one provided on SIG_SETMASK.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Pull ARM: SoC fixes from Olof Johansson:
 "Things have slowed down a lot for us, but we have five more fixes for
  omap and kirkwood below.  Three are for boards setup issues, two are
  SoC-level fixes."

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  ARM: OMAP: igep0020: fix smsc911x dummy regulator id
  ARM: orion5x: Fix GPIO enable bits for MPP9
  ARM: kirkwood: add missing kexec.h include
  ARM: OMAP: Revert "ARM: OMAP: ctrl: Fix CONTROL_DSIPHY register fields"
  ARM: OMAP1: Amstrad Delta: Fix wrong IRQ base in FIQ handler

Pull last minute regman bug fix from Mark Brown:
 "This is a last minute bug fix that was only just noticed since the
  code path that's being exercised here is one that is fairly rarely
  used.  The changelog for the change itself is extremely clear and the
  code itself is obvious to inspection so should be pretty safe."

* tag 'regmap-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap:
  regmap: fix possible memory corruption in regmap_bulk_read()

Pull KVM fixes from Avi Kivity:
 "Two asynchronous page fault fixes (one guest, one host), a powerpc
  page refcount fix, and an ia64 build fix."

* git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: ia64: fix build due to typo
  KVM: PPC: Book3S HV: Fix refcounting of hugepages
  KVM: Do not take reference to mm during async #PF
  KVM: ensure async PF event wakes up vcpu from halt

Pull powerpc fixes from Benjamin Herrenschmidt:
 "Here are a couple of last minute fixes for 3.4 for regressions
  introduced by my rewrite of the lazy irq masking code."

* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
  powerpc/irq: Make alignment & program interrupt behave the same
  powerpc/irq: Fix bug with new lazy IRQ handling code

Merge tag 'omap-fixes-for-v3.4-rc6-take-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into fixes

Fix two board spefific regressions and one regression caused by bad documentation

By Archit Taneja (1) and others
via Tony Lindgren
* tag 'omap-fixes-for-v3.4-rc6-take-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap:
  ARM: OMAP: igep0020: fix smsc911x dummy regulator id
  ARM: OMAP: Revert "ARM: OMAP: ctrl: Fix CONTROL_DSIPHY register fields"
  ARM: OMAP1: Amstrad Delta: Fix wrong IRQ base in FIQ handler

id 0 is already used and causes errors at boot:

WARNING: at fs/sysfs/dir.c:508 sysfs_add_one+0x9c/0xac()
sysfs: cannot create duplicate filename '/devices/platform/reg-fixed-voltage.0'

Fix it by using the next available one (id=1).

This was caused by 5b3689f4 (ARM: OMAP2+: smsc911x: Add fixed
board regulators) that did not account for some regulators
already being used.
Signed-off-by: NEnrico Butera <ebutera@users.berlios.de>
[tony@atomide.com: updated comments for regression causing commit]
Signed-off-by: NTony Lindgren <tony@atomide.com>

The function regmap_bulk_read() calls the regmap_read() for
each register if set of register has volatile and cache is
enabled. In this case, last few register read makes the memory
corruption if the register size is not the size of unsigned int.
The regam_read() takes argument as unsigned int for returning
value and it update the value as
	*val = map->format.parse_val(map->work_buf);
This causes complete 4 bytes (size of unsigned int) to get written.
Now if client pass the memory pointer for value which is equal to the
required size of register count in regmap_bulk_read() then last few
register read actually update the memory beyond passed pointer size.

Avoid this by using local variable for read and then do memcpy()
for actual byte copy to passed pointer based on register size.

I allocated one pointer ptr and take first 16 bytes dump of that
pointer then call regmap_bulk_read() with pointer which is just
on top of this allocated pointer and register count of 128. Here
register size is 1 byte.
The memory trace of last 5 register read are as follows:

[    5.438589] regmap_bulk_read after regamp_read() for register 122
[    5.447421] 0xef993c20 0xef993c00 0x00000000 0x00000001
[    5.467535] regmap_bulk_read after regamp_read() for register 123
[    5.476374] 0xef993c20 0xef993c00 0x00000000 0x00000001
[    5.496425] regmap_bulk_read after regamp_read() for register 124
[    5.505260] 0xef993c20 0xef993c00 0x00000000 0x00000001
[    5.525372] regmap_bulk_read after regamp_read() for register 125
[    5.534205] 0xef993c00 0xef993c00 0x00000000 0x00000001
[    5.554258] regmap_bulk_read after regamp_read() for register 126
[    5.563100] 0xef990000 0xef993c00 0x00000000 0x00000001
[    5.554258] regmap_bulk_read after regamp_read() for register 127
[    5.587108] 0xef000000 0xef993c00 0x00000000 0x00000001

Here it is observed that the memory content at first word started changing
on last 3 regmap_read() and so corruption happened.
Signed-off-by: NLaxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

ASoC: Build fix for SH in 3.4

An API update which wasn't sufficiently thorough in updating the tree...

Fix a recent compilation breakage, caused by a change in SH clock API.
Signed-off-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

s/kcm/kvm/.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

When an IRQ for some reason gets lost, we wait up to a second using
udelay, which is CPU intensive. This patch improves the situation by
waiting about 30 ms in the CPU intensive mode, then stepping down to
using msleep(2) instead. In essence, we trade some granularity in
exchange for less CPU consumption when the waiting time is a bit longer.

As a result, PulseAudio should no longer be killed by the kernel
for taking up to much RT-prio CPU time. At least not for *this* reason.
Signed-off-by: NDavid Henningsson <david.henningsson@canonical.com>
Tested-by: NArun Raghavan <arun.raghavan@collabora.co.uk>
Cc: <stable@kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Merge branch 'kirkwood_fixes_for_v3.4' of git://git.infradead.org/users/jcooper/linux-kirkwood into fixes

By Ben Hutchings (1) and Ian Campbell (1)
via Jason Cooper: "ARM: kirkwood: fixes for v3.4"
* 'kirkwood_fixes_for_v3.4' of git://git.infradead.org/users/jcooper/linux-kirkwood:
  ARM: orion5x: Fix GPIO enable bits for MPP9
  ARM: kirkwood: add missing kexec.h include

Alignment was the last user of the ENABLE_INTS macro, which we can
now remove. All non-syscall exceptions now disable interrupts on
entry, they get re-enabled conditionally from C code. Don't
unconditionally re-enable in program check either, check the
original context.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

We had a case where we could turn on hard interrupts while
leaving the PACA_IRQ_HARD_DIS bit set in the PACA. This can
in turn cause a BUG_ON() to hit in __check_irq_replay() due
to interrupt state getting out of sync.

The assembly code was also way too convoluted. Instead, we
now leave it to the C code to do the right thing which ends
up being smaller and more readable.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Commit 554cdaef ('ARM: orion5x: Refactor
mpp code to use common orion platform mpp.') seems to have accidentally
inverted the GPIO valid bits for MPP9 (only).  For the mv2120 platform
which uses MPP9 as a GPIO LED device, this results in the error:

[   12.711476] leds-gpio: probe of leds-gpio failed with error -22
Reported-by: NHenry von Tresckow <hvontres@gmail.com>
References: http://bugs.debian.org/667446Signed-off-by: NBen Hutchings <ben@decadent.org.uk>
Cc: stable@vger.kernel.org [v3.0+]
Tested-by: NHans Henry von Tresckow <hvontres@gmail.com>
Signed-off-by: NJason Cooper <jason@lakedaemon.net>

Pull regulator fixes from Mark Brown:
 "One small fix for an edge condition in the max8997 driver and a fix
  for a surprise in the devres API which caused devm_regulator_put() to
  not actually put the regulator - a nicer version of this based on an
  improvement of the devres API is queued for 3.5."

* tag 'regulator-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator:
  regulator: Actually free the regulator in devm_regulator_put()
  regulator: Fix the logic to ensure new voltage setting in valid range

Fixes the following build error when CONFIG_KEXEC is enabled:
  CC      arch/arm/mach-kirkwood/board-dt.o
arch/arm/mach-kirkwood/board-dt.c: In function 'kirkwood_dt_init':
arch/arm/mach-kirkwood/board-dt.c:52:2: error: 'kexec_reinit' undeclared (first use in this function)
arch/arm/mach-kirkwood/board-dt.c:52:2: note: each undeclared identifier is reported only once for each function it appears in
Signed-off-by: NIan Campbell <ijc@hellion.org.uk>
[v4, rebase onto recent Linus for repost]
[v3, speak actual English in the commit message, thanks Sergei Shtylyov]
[v2, using linux/kexec.h not asm/kexec.h]
Signed-off-by: NJason Cooper <jason@lakedaemon.net>

Pull drm fixes from Dave Airlie:
 "Two fixes from Intel, one a regression, one because I merged an early
  version of a fix.

  Also the nouveau revert of the i2c code that was tested on the list."

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  drm/nouveau/i2c: resume use of i2c-algo-bit, rather than custom stack
  drm/i915: Do no set Stencil Cache eviction LRA w/a on gen7+
  drm/i915: disable sdvo hotplug on i945g/gm

Merge tag 'stable/for-linus-3.4-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen

Pull xen fixes from Konrad Rzeszutek Wilk:
 - fix to Kconfig to make it fit within 80 line characters,
 - two bootup fixes (AMD 8-core and with PCI BIOS),
 - cleanup code in a Xen PV fb driver,
 - and a crash fix when trying to see non-existent PTE's

* tag 'stable/for-linus-3.4-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
  xen/Kconfig: fix Kconfig layout
  xen/pci: don't use PCI BIOS service for configuration space accesses
  xen/pte: Fix crashes when trying to see non-existent PGD/PMD/PUD/PTEs
  xen/apic: Return the APIC ID (and version) for CPU 0.
  drivers/video/xen-fbfront.c: add missing cleanup code

Pull two percpu fixes from Tejun Heo:
 "One adds missing KERN_CONT on split printk()s and the other makes
  the percpu allocator avoid using PMD_SIZE as atom_size on x86_32.

  Using PMD_SIZE led to vmalloc area exhaustion on certain
  configurations (x86_32 android) and the only cost of using PAGE_SIZE
  instead is static percpu area not being aligned to large page
  mapping."

* 'for-3.4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
  percpu, x86: don't use PMD_SIZE as embedded atom_size on 32bit
  percpu: use KERN_CONT in pcpu_dump_alloc_info()

Pull ARM fixes from Russell King:
 "This is mainly audit fixes, found by folks who happened to enable this
  feature and then found it broke their user applications."

* 'fixes' of git://git.linaro.org/people/rmk/linux-arm:
  ARM: 7414/1: SMP: prevent use of the console when using idmap_pgd
  ARM: 7412/1: audit: use only AUDIT_ARCH_ARM regardless of endianness
  ARM: 7411/1: audit: fix treatment of saved ip register during syscall tracing
  ARM: 7410/1: Add extra clobber registers for assembly in kernel_execve

With the embed percpu first chunk allocator, x86 uses either PAGE_SIZE
or PMD_SIZE for atom_size.  PMD_SIZE is used when CPU supports PSE so
that percpu areas are aligned to PMD mappings and possibly allow using
PMD mappings in vmalloc areas in the future.  Using larger atom_size
doesn't waste actual memory; however, it does require larger vmalloc
space allocation later on for !first chunks.

With reasonably sized vmalloc area, PMD_SIZE shouldn't be a problem
but x86_32 at this point is anything but reasonable in terms of
address space and using larger atom_size reportedly leads to frequent
percpu allocation failures on certain setups.

As there is no reason to not use PMD_SIZE on x86_64 as vmalloc space
is aplenty and most x86_64 configurations support PSE, fix the issue
by always using PMD_SIZE on x86_64 and PAGE_SIZE on x86_32.

v2: drop cpu_has_pse test and make x86_64 always use PMD_SIZE and
    x86_32 PAGE_SIZE as suggested by hpa.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NYanmin Zhang <yanmin.zhang@intel.com>
Reported-by: NShuoX Liu <shuox.liu@intel.com>
Acked-by: NH. Peter Anvin <hpa@zytor.com>
LKML-Reference: <4F97BA98.6010001@intel.com>
Cc: stable@vger.kernel.org

The H_REGISTER_VPA hcall implementation in HV Power KVM needs to pin some
guest memory pages into host memory so that they can be safely accessed
from usermode.  It does this used get_user_pages_fast().  When the VPA is
unregistered, or the VCPUs are cleaned up, these pages are released using
put_page().

However, the get_user_pages() is invoked on the specific memory are of the
VPA which could lie within hugepages.  In case the pinned page is huge,
we explicitly find the head page of the compound page before calling
put_page() on it.

At least with the latest kernel, this is not correct.  put_page() already
handles finding the correct head page of a compound, and also deals with
various counts on the individual tail page which are important for
transparent huge pages.  We don't support transparent hugepages on Power,
but even so, bypassing this count maintenance can lead (when the VM ends)
to a hugepage being released back to the pool with a non-zero mapcount on
one of the tail pages.  This can then lead to a bad_page() when the page
is released from the hugepage pool.

This removes the explicit compound_head() call to correct this bug.
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Acked-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

This reverts commit 785f857d.

The commit causes a problem with the wrong D3 state after suspend
because the call of hda_set_power_state() involves with the power-up
sequence, which changes the power_count, and this confuses the resume
sequence that checks the power_count as well.

Originally, this go-to-D3 sequence should be a simple task without the
power-up sequence.  But, it'd need some proper sanity checks in the
case of power-saved state, so it's not too easy to write now in the
3.4-rc cycle.

In short, the safest option now is to revert this affecting commit.

Of course, we need to clean up and robustify the power-saving code
better for 3.5 kernel.
Reported-by: NKonstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

The call for alc_auto_parse_customize_define() must be done after the
fixup pre-probe initialization.  Otherwise SKU_IGNORE fixup won't work
properly (e.g. HP RP5800 with ALC662 codec).
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

snd_hdsp uses its own ioctls to acquire config- and status information.
Expose the corresponding ioctl handler via ioctl_compat, so that 32bit applications can use it on 64bit kernels.
Signed-off-by: NAndre Schramm <andre.schramm@iosono-sound.com>
Reviewed-by: NAdrian Knoth <adi@drcomp.erfurt.thur.de>
Signed-off-by: NAdrian Knoth <adi@drcomp.erfurt.thur.de>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Fit it into 80 columns so that it is readable in menuconfig.
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The accessing PCI configuration space with the PCI BIOS32 service does
not work in PV guests.

On systems without MMCONFIG or where the BIOS hasn't marked the
MMCONFIG region as reserved in the e820 map, the BIOS service is
probed (even though direct access is preferred) and this hangs.

CC: stable@kernel.org
Acked-by: NJan Beulich <jbeulich@suse.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
[v1: Fixed compile error when CONFIG_PCI is not set]
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

If I try to do "cat /sys/kernel/debug/kernel_page_tables"
I end up with:

BUG: unable to handle kernel paging request at ffffc7fffffff000
IP: [<ffffffff8106aa51>] ptdump_show+0x221/0x480
PGD 0
Oops: 0000 [#1] SMP
CPU 0
.. snip..
RAX: 0000000000000000 RBX: ffffc00000000fff RCX: 0000000000000000
RDX: 0000800000000000 RSI: 0000000000000000 RDI: ffffc7fffffff000

which is due to the fact we are trying to access a PFN that is not
accessible to us. The reason (at least in this case) was that
PGD[256] is set to __HYPERVISOR_VIRT_START which was setup (by the
hypervisor) to point to a read-only linear map of the MFN->PFN array.
During our parsing we would get the MFN (a valid one), try to look
it up in the MFN->PFN tree and find it invalid and return ~0 as PFN.
Then pte_mfn_to_pfn would happilly feed that in, attach the flags
and return it back to the caller. 'ptdump_show' bitshifts it and
gets and invalid value that it tries to dereference.

Instead of doing all of that, we detect the ~0 case and just
return !_PAGE_PRESENT.

This bug has been in existence .. at least until 2.6.37 (yikes!)

CC: stable@kernel.org
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>