st-nci.h already include ndlc.h.
Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Align st-nci driver with other NFC drivers:
- Remove st-nci_ prefix
- Merge se.h in st-nci.h
Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Fields Peak complies with the ISO/IEC 14443A/B, 15693, 18092,
and JIS X 6319-4. It is an NCI based controller.

RF Protocols supported:
 - NFC Forum Type 1 Tags (Jewel, Topaz)
 - NFC Forum Type 2 Tags (Mifare UL)
 - NFC Forum Type 3 Tags (FeliCa)
 - NFC Forum Type 4A (ISO/IEC 14443 A-4 106kbps to 848kbps)
 - NFC Forum Type 4B (ISO/IEC 14443 B-4 106kbps to 848kbps)
 - NFCIP in passive and active modes (ISO/IEC 18092 106kbps
   to 424kbps)
 - B’ (based on ISO/IEC 14443 B-2)
 - iCLASS (based on ISO/IEC 15693-2)
 - Vicinity cards (ISO/IEC 15693-3)
 - Kovio tags (NFC Forum Type 2)

The device can be enumerated using ACPI using the id INT339A.
The 1st GPIO is the IRQ and the 2nd is the RESET pin.
Signed-off-by: Robert Dolca <robert.dolca@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

This functin takes as a parameter a pointer to the nci_dev
struct and the first byte from the values of the first domain
specific parameter that was used for the connection creation.
Signed-off-by: Robert Dolca <robert.dolca@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

If the number of destination speific parameters supplied is 0
the call will fail. If the first destination specific parameter
does not have a value, curr_id will be set to 0.
Signed-off-by: Robert Dolca <robert.dolca@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Initially it was used to create hooks in the driver for
proprietary operations. Currently it is being used for hooks
for both proprietary and generic operations.
Signed-off-by: Robert Dolca <robert.dolca@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

The driver may be required to act when some responses or
notifications arrive. For example the NCI core does not have a
handler for NCI_OP_CORE_GET_CONFIG_RSP. The NFCC can send a
config response that has to be read by the driver and the packet
may contain vendor specific data.

The Fields Peak driver needs to take certain actions when a reset
notification arrives (packet also not handled by the nfc core).

The driver handlers do not interfere with the core and they are
called after the core processes the packet.
Signed-off-by: Robert Dolca <robert.dolca@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

This allows sending core commands from the driver. The driver
should be able to send NCI core commands like CORE_GET_CONFIG_CMD.
Signed-off-by: Robert Dolca <robert.dolca@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

The driver should know that it can continue with post setup where
setup left off. Being able to execute post_setup when setup fails
may force the developer to keep this state in the driver.
Signed-off-by: Robert Dolca <robert.dolca@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Add NCI_OP_CORE_GET_CONFIG_CMD, NCI_OP_CORE_GET_CONFIG_RSP
and NCI_OP_CORE_RESET_NTF.
Signed-off-by: Robert Dolca <robert.dolca@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

FDP driver needs to send the firmware as regular packets
(not fragmented). The driver should have a way to
get the max packet size for a given connection.
Signed-off-by: Robert Dolca <robert.dolca@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

For the firmware update the driver may use nci_send_data.
Signed-off-by: Robert Dolca <robert.dolca@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Rename it to se.c to keep the driver files namespace consistent.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

The exit label performs device_unlock(&dev->dev);, which will fail when dev
is NULL, and nfc_put_device(dev);, which is not useful when dev is NULL, so
just exit the function immediately.

Problem found using scripts/coccinelle/null/deref_null.cocci
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

There is no need to have the 'struct nfcwilink *drv' variable static in the
probe function.
It only wastes a few bytes of memory.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

The only instance of a nxp_nci_phy_ops structure is never modified.  Thus
the declaration of the structure and all references to the structure type
can be made const.

Done with the help of Coccinelle.
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

As I understand it, the core nfcmrvl module is useless without
either the USB or the UART access module. So hide NFC_MRVL and select
it automatically if either NFC_MRVL_USB or NFC_MRVL_UART is selected.

This avoids presenting NFC_MRVL when neither NFC_MRVL_USB nor
NFC_MRVL_UART can be selected.
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Lauro Ramos Venancio <lauro.venancio@openbossa.org>
Cc: Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

As I understand it, the core nfc_microread module is useless without
either the I2C or the MEI access module. So hide NFC_MICROREAD and
select it automatically if either NFC_MICROREAD_I2C or
NFC_MICROREAD_MEI is selected.

This avoids presenting NFC_MICROREAD when neither NFC_MICROREAD_I2C
nor NFC_MICROREAD_MEI can be selected.
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Lauro Ramos Venancio <lauro.venancio@openbossa.org>
Cc: Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

As I understand it, the core nfc_pn544 module is useless without
either the I2C or the MEI access module. So hide NFC_PN544 and
select it automatically if either NFC_PN544_I2C or NFC_PN544_MEI is
selected.

This avoids presenting NFC_PN544 when neither NFC_PN544_I2C nor
NFC_PN544_MEI can be selected.
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Lauro Ramos Venancio <lauro.venancio@openbossa.org>
Cc: Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

The Documentation/devicetree/bindings/net/nfc/trf7970a.txt DT binding doc
lists "ti,trf7970a" as a compatible string but the corresponding driver
does not have an OF match table. Add the table to the driver so the SPI
core can do an OF style match.
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Robert Baldyga <r.baldyga@samsung.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Make NFC_S3FWRN5 select CRYPTO to fix below build errors:

ERROR: "crypto_destroy_tfm" [drivers/nfc/s3fwrn5/s3fwrn5.ko] undefined!
ERROR: "crypto_alloc_base" [drivers/nfc/s3fwrn5/s3fwrn5.ko] undefined!
scripts/Makefile.modpost:91: recipe for target '__modpost' failed
make[1]: *** [__modpost] Error 1
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Robert Baldyga <r.baldyga@samsung.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC_DEBUG is not defined in Kconfig and since DEBUG is not used
anywhere in this directory, we can safely remove this line.
Signed-off-by: Valentin Rothberg <valentinrothberg@gmail.com>
Acked-by: Robert Baldyga <r.baldyga@samsung.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Since we do not know in which context drivers will call these
routines, they should use the unlocked version of nci_request,
i.e. __nci_request.
It is up to drivers to know/decide if they need to take the
req_lock mutex before calling those routines. When being called
from the NCI setup routine there is no need to do so as ops->setup
is called under req_lock.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Conflicts:
	net/dsa/slave.c

net/dsa/slave.c simply had overlapping changes.
Signed-off-by: David S. Miller <davem@davemloft.net>

Pull MMC fixes from Ulf Hansson:
 "Here are some mmc fixes intended for v4.3 rc4:

  MMC core:
   - Allow users of mmc_of_parse() to succeed when CONFIG_GPIOLIB is
     unset
   - Prevent infinite loop of re-tuning for CRC-errors for CMD19 and
     CMD21

   MMC host:
   - pxamci: Fix issues with card detect
   - sunxi: Fix clk-delay settings"

* tag 'mmc-v4.3-rc3' of git://git.linaro.org/people/ulf.hansson/mmc:
  mmc: core: fix dead loop of mmc_retune
  mmc: pxamci: fix card detect with slot-gpio API
  mmc: sunxi: Fix clk-delay settings
  mmc: core: Don't return an error for CD/WP GPIOs when GPIOLIB is unset

Pull IOVA fixes from David Woodhouse:
 "The main fix here is the first one, fixing the over-allocation of
   size-aligned requests.  The other patches simply make the existing
  IOVA code available to users other than the Intel VT-d driver, with no
  functional change.

  I concede the latter really *should* have been submitted during the
  merge window, but since it's basically risk-free and people are
  waiting to build on top of it and it's my fault I didn't get it in, I
  (and they) would be grateful if you'd take it"

* git://git.infradead.org/intel-iommu:
  iommu: Make the iova library a module
  iommu: iova: Export symbols
  iommu: iova: Move iova cache management to the iova library
  iommu/iova: Avoid over-allocating when size-aligned

Merge misc fixes from Andrew Morton:
 "12 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  dmapool: fix overflow condition in pool_find_page()
  thermal: avoid division by zero in power allocator
  memcg: remove pcp_counter_lock
  kprobes: use _do_fork() in samples to make them work again
  drivers/input/joystick/Kconfig: zhenhua.c needs BITREVERSE
  memcg: make mem_cgroup_read_stat() unsigned
  memcg: fix dirty page migration
  dax: fix NULL pointer in __dax_pmd_fault()
  mm: hugetlbfs: skip shared VMAs when unmapping private pages to satisfy a fault
  mm/slab: fix unexpected index mapping result of kmalloc_size(INDEX_NODE+1)
  userfaultfd: remove kernel header include from uapi header
  arch/x86/include/asm/efi.h: fix build failure

Pull power management and ACPI fixes from Rafael Wysocki:
 "These are fixes mostly, for a few changes made in this cycle (the
  intel_idle driver, the OPP library, the ACPI EC driver, turbostat) and
  for some issues that have just been discovered (ACPI PCI IRQ
  management, PCI power management documentation, turbostat), with a
  couple of cleanups on top of them.

  Specifics:

   - intel_idle driver fixup for the recently added Skylake chips
     support (Len Brown).

   - Operating Performance Points (OPP) library fix related to the
     recently added support for new DT bindings and a fix for a typo in
     a comment (Viresh Kumar, Stephen Boyd).

   - ACPI EC driver fix for a recently introduced memory leak in an
     error code path (Lv Zheng).

   - ACPI PCI IRQ management fix for the issue where an ISA IRQ is
     shared with a PCI device which requires it to be configured in a
     different way and may cause an interrupt storm to happen as a
     result with an extra ACPI SCI IRQ handling simplification on top of
     it (Jiang Liu).

   - Update of the PCI power management documentation that became
     outdated and started to actively confuse the readers to make it
     actually reflect the code (Rafael J Wysocki).

   - turbostat fixes including an IVB Xeon regression fix (related to
     the --debug command line option), Skylake adjustment for the TSC
     running at a frequency that doesn't match the base one exactly, and
     a Knights Landing quirk to account for the fact that it only
     updates APERF and MPERF every 1024 clock cycles plus bumping up the
     turbostat version number (Len Brown, Hubert Chrzaniuk)"

* tag 'pm+acpi-4.3-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  tools/power turbosat: update version number
  tools/power turbostat: SKL: Adjust for TSC difference from base frequency
  tools/power turbostat: KNL workaround for %Busy and Avg_MHz
  tools/power turbostat: IVB Xeon: fix --debug regression
  ACPI / PCI: Remove duplicated penalty on SCI IRQ
  ACPI, PCI, irq: Do not share PCI IRQ with ISA IRQ
  ACPI / EC: Fix a memory leak issue in acpi_ec_query()
  PM / OPP: Fix typo modifcation -> modification
  PCI / PM: Update runtime PM documentation for PCI devices
  PM / OPP: of_property_count_u32_elems() can return errors
  intel_idle: Skylake Client Support - updated

Pull networking fixes from David Miller:

1) Fix regression in SKB partial checksum handling, from Pravin B
   Shalar.

2) Fix VLAN inside of VXLAN handling in i40e driver, from Jesse
   Brandeburg.

3) Cure softlockups during accept() in SCTP, from Karl Heiss.

4) MSG_PEEK should return multiple SKBs worth of data in AF_UNIX, from
   Aaron Conole.

5) IPV6 erroneously ignores output interface specifier in lookup key for
   route lookups, fix from David Ahern.

6) In Marvell DSA driver, forward unknown frames to CPU port, from
   Andrew Lunn.

7) Mission flow flag initializations in some code paths, from David
   Ahern.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
  net: Initialize flow flags in input path
  net: dsa: fix preparation of a port STP update
  testptp: Silence compiler warnings on ppc64
  net/mlx4: Handle return codes in mlx4_qp_attach_common
  dsa: mv88e6xxx: Enable forwarding for unknown to the CPU port
  skbuff: Fix skb checksum partial check.
  net: ipv6: Add RT6_LOOKUP_F_IFACE flag if oif is set
  net sysfs: Print link speed as signed integer
  bna: fix error handling
  af_unix: return data from multiple SKBs on recv() with MSG_PEEK flag
  af_unix: Convert the unix_sk macro to an inline function for type safety
  net: sctp: Don't use 64 kilobyte lookup table for four elements
  l2tp: protect tunnel->del_work by ref_count
  net/ibm/emac: bump version numbers for correct work with ethtool
  sctp: Prevent soft lockup when sctp_accept() is called during a timeout event
  sctp: Whitespace fix
  i40e/i40evf: check for stopped admin queue
  i40e: fix VLAN inside VXLAN
  r8169: fix handling rtl_readphy result
  net: hisilicon: fix handling platform_get_irq result

If a DMA pool lies at the very top of the dma_addr_t range (as may
happen with an IOMMU involved), the calculated end address of the pool
wraps around to zero, and page lookup always fails.

Tweak the relevant calculation to be overflow-proof.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Sakari Ailus <sakari.ailus@iki.fi>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

During boot I get a div by zero Oops regression starting in v4.3-rc3.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Javi Merino <javi.merino@arm.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Cc: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 733a572e ("memcg: make mem_cgroup_read_{stat|event}() iterate
possible cpus instead of online") removed the last use of the per memcg
pcp_counter_lock but forgot to remove the variable.

Kill the vestigial variable.
Signed-off-by: Greg Thelen <gthelen@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 3033f14a ("clone: support passing tls argument via C rather
than pt_regs magic") introduced _do_fork() that allowed to pass @tls
parameter.

The old do_fork() is defined only for architectures that are not ready
to use this way and do not define HAVE_COPY_THREAD_TLS.

Let's use _do_fork() in the kprobe examples to make them work again on
all architectures.
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thiago Macieira <thiago.macieira@intel.com>
Cc: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

It uses bitrev8(), so it must ensure that lib/bitrev.o gets included in
vmlinux.

Cc: Fengguang Wu <fengguang.wu@gmail.com>
Cc: yalin wang <yalin.wang2010@gmail.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mem_cgroup_read_stat() returns a page count by summing per cpu page
counters.  The summing is racy wrt.  updates, so a transient negative
sum is possible.  Callers don't want negative values:

 - mem_cgroup_wb_stats() doesn't want negative nr_dirty or nr_writeback.
   This could confuse dirty throttling.

 - oom reports and memory.stat shouldn't show confusing negative usage.

 - tree_usage() already avoids negatives.

Avoid returning negative page counts from mem_cgroup_read_stat() and
convert it to unsigned.

[akpm@linux-foundation.org: fix old typo while we're in there]
Signed-off-by: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>	[4.2+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The problem starts with a file backed dirty page which is charged to a
memcg.  Then page migration is used to move oldpage to newpage.

Migration:
 - copies the oldpage's data to newpage
 - clears oldpage.PG_dirty
 - sets newpage.PG_dirty
 - uncharges oldpage from memcg
 - charges newpage to memcg

Clearing oldpage.PG_dirty decrements the charged memcg's dirty page
count.

However, because newpage is not yet charged, setting newpage.PG_dirty
does not increment the memcg's dirty page count.  After migration
completes newpage.PG_dirty is eventually cleared, often in
account_page_cleaned().  At this time newpage is charged to a memcg so
the memcg's dirty page count is decremented which causes underflow
because the count was not previously incremented by migration.  This
underflow causes balance_dirty_pages() to see a very large unsigned
number of dirty memcg pages which leads to aggressive throttling of
buffered writes by processes in non root memcg.

This issue:
 - can harm performance of non root memcg buffered writes.
 - can report too small (even negative) values in
   memory.stat[(total_)dirty] counters of all memcg, including the root.

To avoid polluting migrate.c with #ifdef CONFIG_MEMCG checks, introduce
page_memcg() and set_page_memcg() helpers.

Test:
    0) setup and enter limited memcg
    mkdir /sys/fs/cgroup/test
    echo 1G > /sys/fs/cgroup/test/memory.limit_in_bytes
    echo $$ > /sys/fs/cgroup/test/cgroup.procs

    1) buffered writes baseline
    dd if=/dev/zero of=/data/tmp/foo bs=1M count=1k
    sync
    grep ^dirty /sys/fs/cgroup/test/memory.stat

    2) buffered writes with compaction antagonist to induce migration
    yes 1 > /proc/sys/vm/compact_memory &
    rm -rf /data/tmp/foo
    dd if=/dev/zero of=/data/tmp/foo bs=1M count=1k
    kill %
    sync
    grep ^dirty /sys/fs/cgroup/test/memory.stat

    3) buffered writes without antagonist, should match baseline
    rm -rf /data/tmp/foo
    dd if=/dev/zero of=/data/tmp/foo bs=1M count=1k
    sync
    grep ^dirty /sys/fs/cgroup/test/memory.stat

                       (speed, dirty residue)
             unpatched                       patched
    1) 841 MB/s 0 dirty pages          886 MB/s 0 dirty pages
    2) 611 MB/s -33427456 dirty pages  793 MB/s 0 dirty pages
    3) 114 MB/s -33427456 dirty pages  891 MB/s 0 dirty pages

    Notice that unpatched baseline performance (1) fell after
    migration (3): 841 -> 114 MB/s.  In the patched kernel, post
    migration performance matches baseline.

Fixes: c4843a75 ("memcg: add per cgroup dirty page accounting")
Signed-off-by: Greg Thelen <gthelen@google.com>
Reported-by: Dave Hansen <dave.hansen@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>	[4.2+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 46c043ed ("mm: take i_mmap_lock in unmap_mapping_range() for
DAX") moved some code in __dax_pmd_fault() that was responsible for
zeroing newly allocated PMD pages.  The new location didn't properly set
up 'kaddr', so when run this code resulted in a NULL pointer BUG.

Fix this by getting the correct 'kaddr' via bdev_direct_access().
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reported-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

SunDong reported the following on

  https://bugzilla.kernel.org/show_bug.cgi?id=103841

	I think I find a linux bug, I have the test cases is constructed. I
	can stable recurring problems in fedora22(4.0.4) kernel version,
	arch for x86_64.  I construct transparent huge page, when the parent
	and child process with MAP_SHARE, MAP_PRIVATE way to access the same
	huge page area, it has the opportunity to lead to huge page copy on
	write failure, and then it will munmap the child corresponding mmap
	area, but then the child mmap area with VM_MAYSHARE attributes, child
	process munmap this area can trigger VM_BUG_ON in set_vma_resv_flags
	functions (vma - > vm_flags & VM_MAYSHARE).

There were a number of problems with the report (e.g.  it's hugetlbfs that
triggers this, not transparent huge pages) but it was fundamentally
correct in that a VM_BUG_ON in set_vma_resv_flags() can be triggered that
looks like this

	 vma ffff8804651fd0d0 start 00007fc474e00000 end 00007fc475e00000
	 next ffff8804651fd018 prev ffff8804651fd188 mm ffff88046b1b1800
	 prot 8000000000000027 anon_vma           (null) vm_ops ffffffff8182a7a0
	 pgoff 0 file ffff88106bdb9800 private_data           (null)
	 flags: 0x84400fb(read|write|shared|mayread|maywrite|mayexec|mayshare|dontexpand|hugetlb)
	 ------------
	 kernel BUG at mm/hugetlb.c:462!
	 SMP
	 Modules linked in: xt_pkttype xt_LOG xt_limit [..]
	 CPU: 38 PID: 26839 Comm: map Not tainted 4.0.4-default #1
	 Hardware name: Dell Inc. PowerEdge R810/0TT6JF, BIOS 2.7.4 04/26/2012
	 set_vma_resv_flags+0x2d/0x30

The VM_BUG_ON is correct because private and shared mappings have
different reservation accounting but the warning clearly shows that the
VMA is shared.

When a private COW fails to allocate a new page then only the process
that created the VMA gets the page -- all the children unmap the page.
If the children access that data in the future then they get killed.

The problem is that the same file is mapped shared and private.  During
the COW, the allocation fails, the VMAs are traversed to unmap the other
private pages but a shared VMA is found and the bug is triggered.  This
patch identifies such VMAs and skips them.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: SunDong <sund_sky@126.com>
Reviewed-by: Michal Hocko <mhocko@suse.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: David Rientjes <rientjes@google.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit description is copied from the original post of this bug:

  http://comments.gmane.org/gmane.linux.kernel.mm/135349

Kernels after v3.9 use kmalloc_size(INDEX_NODE + 1) to get the next
larger cache size than the size index INDEX_NODE mapping.  In kernels
3.9 and earlier we used malloc_sizes[INDEX_L3 + 1].cs_size.

However, sometimes we can't get the right output we expected via
kmalloc_size(INDEX_NODE + 1), causing a BUG().

The mapping table in the latest kernel is like:
    index = {0,   1,  2 ,  3,  4,   5,   6,   n}
     size = {0,   96, 192, 8, 16,  32,  64,   2^n}
The mapping table before 3.10 is like this:
    index = {0 , 1 , 2,   3,  4 ,  5 ,  6,   n}
    size  = {32, 64, 96, 128, 192, 256, 512, 2^(n+3)}

The problem on my mips64 machine is as follows:

(1) When configured DEBUG_SLAB && DEBUG_PAGEALLOC && DEBUG_LOCK_ALLOC
    && DEBUG_SPINLOCK, the sizeof(struct kmem_cache_node) will be "150",
    and the macro INDEX_NODE turns out to be "2": #define INDEX_NODE
    kmalloc_index(sizeof(struct kmem_cache_node))

(2) Then the result of kmalloc_size(INDEX_NODE + 1) is 8.

(3) Then "if(size >= kmalloc_size(INDEX_NODE + 1)" will lead to "size
    = PAGE_SIZE".

(4) Then "if ((size >= (PAGE_SIZE >> 3))" test will be satisfied and
    "flags |= CFLGS_OFF_SLAB" will be covered.

(5) if (flags & CFLGS_OFF_SLAB)" test will be satisfied and will go to
    "cachep->slabp_cache = kmalloc_slab(slab_size, 0u)", and the result
    here may be NULL while kernel bootup.

(6) Finally,"BUG_ON(ZERO_OR_NULL_PTR(cachep->slabp_cache));" causes the
    BUG info as the following shows (may be only mips64 has this problem):

This patch fixes the problem of kmalloc_size(INDEX_NODE + 1) and removes
the BUG by adding 'size >= 256' check to guarantee that all necessary
small sized slabs are initialized regardless sequence of slab size in
mapping table.

Fixes: e3366016 ("slab: Use common kmalloc_index/kmalloc_size...")
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reported-by: Liuhailong <liu.hailong6@zte.com.cn>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>