The Blackfin port has been removed from the kernel, also remove the
blackfin specific bits from the checkstack.pl script.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

A number of architectures are being removed from the kernel, so
we no longer need to test them.
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

These two architectures are getting removed, so we no longer
need the special cases.
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

A number of architecture ports are obsolete and getting dropped,
so we no longer want to track the respective features.

We already removed the lines for metag and mn10300, this does
the same edits for all the others.

For the remaining 21 architectures, this shows how many are known
to implement each given feature:

19 time/modern-timekeeping/arch-support.txt
19 time/clockevents/arch-support.txt
15 core/tracehook/arch-support.txt
14 core/generic-idle-thread/arch-support.txt
13 locking/lockdep/arch-support.txt
12 io/dma-api-debug/arch-support.txt
11 debug/kgdb/arch-support.txt
10 time/virt-cpuacct/arch-support.txt
 9 debug/kretprobes/arch-support.txt
 9 debug/kprobes/arch-support.txt
 8 vm/THP/arch-support.txt
 8 vm/pte_special/arch-support.txt
 8 vm/numa-memblock/arch-support.txt
 8 io/sg-chain/arch-support.txt
 7 perf/kprobes-event/arch-support.txt
 7 locking/rwsem-optimized/arch-support.txt
 7 debug/gcov-profile-all/arch-support.txt
 7 core/jump-labels/arch-support.txt
 7 core/BPF-JIT/arch-support.txt
 6 vm/ELF-ASLR/arch-support.txt
 6 time/context-tracking/arch-support.txt
 6 seccomp/seccomp-filter/arch-support.txt
 6 debug/stackprotector/arch-support.txt
 5 time/irq-time-acct/arch-support.txt
 5 io/dma-contiguous/arch-support.txt
 5 debug/uprobes/arch-support.txt
 4 vm/ioremap_prot/arch-support.txt
 4 time/arch-tick-broadcast/arch-support.txt
 4 perf/perf-stackdump/arch-support.txt
 4 perf/perf-regs/arch-support.txt
 3 debug/KASAN/arch-support.txt
 2 vm/PG_uncached/arch-support.txt
 2 vm/huge-vmap/arch-support.txt
 2 sched/numa-balancing/arch-support.txt
 2 sched/membarrier-sync-core/arch-support.txt
 2 locking/cmpxchg-local/arch-support.txt
 2 debug/optprobes/arch-support.txt
 2 debug/kprobes-on-ftrace/arch-support.txt
 1 vm/TLB/arch-support.txt
 1 locking/queued-spinlocks/arch-support.txt
 1 locking/queued-rwlocks/arch-support.txt
 1 debug/user-ret-profiler/arch-support.txt
 0 lib/strncasecmp/arch-support.txt

Note that the list does not include riscv or nds32 yet, these still
need to be added.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

The score architecture used a number of old system calls for compatibility
with a traditional libc port, all architectures that got added later
skip these. With score out of the way, we can finally clean up the
syscall list to no longer provide these.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Unlike system call numbers the assignment of si_codes has never had a
reason to be made per architecture.  Some architectures have had unique
conditions to report and reporting those conditions needed new si_codes.
Nothing has ever needed si_codes to have different values on different
architectures.  The si_code space is vast so even with defining all
si_codes on all architectures there is no danger in running out of
si_code values.

The history of the si_codes BUS_MCEERR_AR, BUS_MCEER_AO, SEGV_BNDERR,
and SEGV_PKUERR show that a need of one architecture frequently becomes
a need of another architecture which makes sharing si_codes between
architectures a positive benefit and something to be encouraged.

Where there are no conflicts with the historical ia64 arch specific
si_codes and any other si_codes make them generic si_codes.  We might
need them on another architecture someday.

This leaves only the good example of arch generic si_codes in the kernel
for future architectures and architecture enhancments to follow.
Without bad examples to follow it should be easy to avoid the mistakes
of the past.
Reported-by: Eric W. Biederman <ebiederm@xmission.com>
[arnd: took Eric's changelog text]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

The frv, tile and blackfin architectures are being removed, so
we can clean up this header by removing all the special cases
except those for ia64.

The SEGV_BNDERR and BUS_MCEERR_AR si_code macros are now
defined unconditionally on all remaining architectures.
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

A lot of Kconfig symbols have architecture specific dependencies.
In those cases that depend on architectures we have already removed,
they can be omitted.
Acked-by: Kalle Valo <kvalo@codeaurora.org>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Tile was the only remaining architecture to implement alloc_remap(),
and since that is being removed, there is no point in keeping this
function.

Removing all callers simplifies the mem_map handling.
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

The CONFIG_MPU option was only defined on blackfin, and that architecture
is now being removed, so the respective code can be simplified.

A lot of other microcontrollers have an MPU, but I suspect that if we
want to bring that support back, we'd do it differently anyway.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Hardwall is a tile specific feature, and with the removal of the
tile architecture, this has become dead code, so let's remove it.

Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

The port was added back in 2000 so it's no longer even a good source
of inspiration for newer ports (if it ever was)

The last SoC (ARTPEC-3) with a CRIS main CPU was launched in 2008.

Coupled with time and working developer board hardware being
in low supply, it's time to drop the port from Linux.

So long and thanks for all the fish!
Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

The Tile architecture port was added by Chris Metcalf in 2010, and
maintained until early 2018 when he orphaned it due to his departure
from Mellanox, and nobody else stepped up to maintain it. The product
line is still around in the form of the BlueField SoC, but no longer
uses the Tile architecture.

There are also still products for sale with Tile-GX SoCs, notably the
Mikrotik CCR router family. The products all use old (linux-3.3) kernels
with lots of patches and won't be upgraded by their manufacturers. There
have been efforts to port both OpenWRT and Debian to these, but both
projects have stalled and are very unlikely to be continued in the future.

Given that we are reasonably sure that nobody is still using the port
with an upstream kernel any more, it seems better to remove it now while
the port is in a good shape than to let it bitrot for a few years first.

Cc: Chris Metcalf <chris.d.metcalf@gmail.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: http://www.mellanox.com/page/npu_multicore_overview
Link: https://jenkins.debian.net/view/rebootstrap/job/rebootstrap_tilegx_gcc7/Signed-off-by: Arnd Bergmann <arnd@arndb.de>

The Analog Devices Blackfin port was added in 2007 and was rather
active for a while, but all work on it has come to a standstill
over time, as Analog have changed their product line-up.

Aaron Wu confirmed that the architecture port is no longer relevant,
and multiple people suggested removing blackfin independently because
of some of its oddities like a non-working SMP port, and the amount of
duplication between the chip variants, which cause extra work when
doing cross-architecture changes.

Link: https://docs.blackfin.uclinux.org/Acked-by: Aaron Wu <Aaron.Wu@analog.com>
Acked-by: Bryan Wu <cooloney@gmail.com>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Mike Frysinger <vapier@chromium.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

The Sunplus S+core architecture was added in 2009 by Chen Liqin,
who has been co-maintaining it with Lennox Wu <lennox.wu@gmail.com>
since then, but after they both left the company, nobody else has shown
any interest in the port and it has seen almost no activity other than
tree-wide changes.

The gcc port was removed a few years ago due to the inactivity.

While the sunplus website still advertises products with unspecified
RISC cores that might be S+core based, it's very clear that the Linux
port is completely abandoned at this point.

This removes all files related to the architecture.
Acked-by: Lennox Wu <lennox.wu@gmail.com>
Link: http://www.sunplus.com/Signed-off-by: Arnd Bergmann <arnd@arndb.de>

The Mitsubishi/Renesas m32r architecture has been around for many years,
but the Linux port has been obsolete for a very long time as well, with
the last significant updates done for linux-2.6.14.

While some m32r microcontrollers are still being marketed by Renesas,
those are apparently no longer possible to support, mainly due to the
lack of an external memory interface.

Hirokazu Takata was the maintainer until the architecture got marked
Orphaned in 2014.

Link: http://www.linux-m32r.org/
Link: https://www.renesas.com/en-eu/products/microcontrollers-microprocessors/m32r.html
Cc: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

The Fujitsu FRV kernel port has been around for a long time, but has not
seen regular updates in several years and instead was marked 'Orphaned'
in 2016 by long-time maintainer David Howells.

The SoC product line apparently is apparently still around in the form
of the Socionext Milbeaut image processor, but this one no longer uses
the FRV CPU cores.

This removes all FRV specific files from the kernel.

Link: http://www.socionext.com/en/products/assp/milbeaut/
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Remove the MN10300 arch as the hardware is defunct.
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Masahiro Yamada <yamada.masahiro@socionext.com>
cc: linux-am33-list@redhat.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Merge tag 'metag_remove_2' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/jhogan/metag into asm-generic

Remove metag architecture

These patches remove the metag architecture and tightly dependent
drivers from the kernel. With the 4.16 kernel the ancient gcc 4.2.4
based metag toolchain we have been using is hitting compiler bugs, so
now seems a good time to drop it altogether.

* tag 'metag_remove_2' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/jhogan/metag:
  i2c: img-scb: Drop METAG dependency
  media: img-ir: Drop METAG dependency
  watchdog: imgpdc: Drop METAG dependency
  MAINTAINERS/CREDITS: Drop METAG ARCHITECTURE
  tty: Remove metag DA TTY and console driver
  clocksource: Remove metag generic timer driver
  irqchip: Remove metag irqchip drivers
  Drop a bunch of metag references
  docs: Remove remaining references to metag
  docs: Remove metag docs
  metag: Remove arch/metag/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Now that arch/metag/ has been removed, remove the METAG dependency from
the IMG SCB I2C device driver. The hardware is also present on MIPS SoCs
so the driver still has value.
Signed-off-by: James Hogan <jhogan@kernel.org>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Cc: linux-i2c@vger.kernel.org
Cc: linux-metag@vger.kernel.org

Now that arch/metag/ has been removed, remove the METAG dependency from
the IMG IR device driver. The hardware is also present on MIPS SoCs so
the driver still has value.
Signed-off-by: James Hogan <jhogan@kernel.org>
Acked-by: Sean Young <sean@mess.org>
Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: linux-media@vger.kernel.org
Cc: linux-metag@vger.kernel.org

Now that arch/metag/ has been removed, remove the METAG dependency from
the IMG IR device driver. The hardware is also present on MIPS SoCs so
the driver still has value.
Signed-off-by: James Hogan <jhogan@kernel.org>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: linux-watchdog@vger.kernel.org
Cc: linux-metag@vger.kernel.org

The core Meta architecture support has now been removed, so drop the
MAINTAINERS entry and add an entry to CREDITS.
Signed-off-by: James Hogan <jhogan@kernel.org>
Cc: linux-metag@vger.kernel.org

Now that arch/metag/ has been removed, remove the metag DA TTY and
console driver. It is of no value without the architecture code.
Signed-off-by: James Hogan <jhogan@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-metag@vger.kernel.org

Pull x86 fixes from Thomas Gleixner:
 "A small set of fixes for x86:

   - Add missing instruction suffixes to assembly code so it can be
     compiled by newer GAS versions without warnings.

   - Switch refcount WARN exceptions to UD2 as we did in general

   - Make the reboot on Intel Edison platforms work

   - A small documentation update so text and sample command match"

* 'x86/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  Documentation, x86, resctrl: Make text and sample command match
  x86/platform/intel-mid: Handle Intel Edison reboot correctly
  x86/asm: Add instruction suffixes to bitops
  x86/entry/64: Add instruction suffix
  x86/refcounts: Switch to UD2 for exceptions

Pull x86/pti fixes from Thomas Gleixner:
 "Three fixes related to melted spectrum:

   - Sync the cpu_entry_area page table to initial_page_table on 32 bit.

     Otherwise suspend/resume fails because resume uses
     initial_page_table and triggers a triple fault when accessing the
     cpu entry area.

   - Zero the SPEC_CTL MRS on XEN before suspend to address a
     shortcoming in the hypervisor.

   - Fix another switch table detection issue in objtool"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cpu_entry_area: Sync cpu_entry_area to initial_page_table
  objtool: Fix another switch table detection issue
  x86/xen: Zero MSR_IA32_SPEC_CTRL before suspend

Pull timer fixes from Thomas Gleixner:
 "A small set of fixes from the timer departement:

   - Add a missing timer wheel clock forward when migrating timers off a
     unplugged CPU to prevent operating on a stale clock base and
     missing timer deadlines.

   - Use the proper shift count to extract data from a register value to
     prevent evaluating unrelated bits

   - Make the error return check in the FSL timer driver work correctly.
     Checking an unsigned variable for less than zero does not really
     work well.

   - Clarify the confusing comments in the ARC timer code"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timers: Forward timer base before migrating timers
  clocksource/drivers/arc_timer: Update some comments
  clocksource/drivers/mips-gic-timer: Use correct shift count to extract data
  clocksource/drivers/fsl_ftm_timer: Fix error return checking

Pull irq fixlet from Thomas Gleixner:
 "Just a documentation update for the missing device tree property of
  the R-Car M3N interrupt controller"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  dt-bindings/irqchip/renesas-irqc: Document R-Car M3-N support

Pull btrfs fixes from David Sterba:

 - when NR_CPUS is large, a SRCU structure can significantly inflate
   size of the main filesystem structure that would not be possible to
   allocate by kmalloc, so the kvalloc fallback is used

 - improved error handling

 - fix endiannes when printing some filesystem attributes via sysfs,
   this is could happen when a filesystem is moved between different
   endianity hosts

 - send fixes: the NO_HOLE mode should not send a write operation for a
   file hole

 - fix log replay for for special files followed by file hardlinks

 - fix log replay failure after unlink and link combination

 - fix max chunk size calculation for DUP allocation

* tag 'for-4.16-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  Btrfs: fix log replay failure after unlink and link combination
  Btrfs: fix log replay failure after linking special file and fsync
  Btrfs: send, fix issuing write op when processing hole in no data mode
  btrfs: use proper endianness accessors for super_copy
  btrfs: alloc_chunk: fix DUP stripe size handling
  btrfs: Handle btrfs_set_extent_delalloc failure in relocate_file_extent_cluster
  btrfs: handle failure of add_pending_csums
  btrfs: use kvzalloc to allocate btrfs_fs_info

Pull i2c fixes from Wolfram Sang:
 "A driver fix and a documentation fix (which makes dependency handling
  for the next cycle easier)"

* 'i2c/for-current-fixed' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: octeon: Prevent error message on bus error
  dt-bindings: at24: sort manufacturers alphabetically

Pull libnvdimm fixes from Dan Williams:
 "A 4.16 regression fix, three fixes for -stable, and a cleanup fix:

   - During the merge window support for the new ACPI NVDIMM Platform
     Capabilities structure disabled support for "deep flush", a
     force-unit- access like mechanism for persistent memory. Restore
     that mechanism.

   - VFIO like RDMA is yet one more memory registration / pinning
     interface that is incompatible with Filesystem-DAX. Disable long
     term pins of Filesystem-DAX mappings via VFIO.

   - The Filesystem-DAX detection to prevent long terms pins mistakenly
     also disabled Device-DAX pins which are not subject to the same
     block- map collision concerns.

   - Similar to the setup path, softlockup warnings can trigger in the
     shutdown path for large persistent memory namespaces. Teach
     for_each_device_pfn() to perform cond_resched() in all cases.

   - Boaz noticed that the might_sleep() in dax_direct_access() is stale
     as of the v4.15 kernel.

  These have received a build success notification from the 0day robot,
  and the longterm pin fixes have appeared in -next. However, I recently
  rebased the tree to remove some other fixes that need to be reworked
  after review feedback.

* 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  memremap: fix softlockup reports at teardown
  libnvdimm: re-enable deep flush for pmem devices via fsync()
  vfio: disable filesystem-dax page pinning
  dax: fix vma_is_fsdax() helper
  dax: ->direct_access does not sleep anymore

Merge tag 'kbuild-fixes-v4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - suppress sparse warnings about unknown attributes

 - fix typos and stale comments

 - fix build error of arch/sh

 - fix wrong use of ld-option vs cc-ldoption

 - remove redundant GCC_PLUGINS_CFLAGS assignment

 - fix another memory leak of Kconfig

 - fix line number in error messages of Kconfig

 - do not write confusing CONFIG_DEFCONFIG_LIST out to .config

 - add xstrdup() to Kconfig to handle memory shortage errors

 - show also a Debian package name if ncurses is missing

* tag 'kbuild-fixes-v4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  MAINTAINERS: take over Kconfig maintainership
  kconfig: fix line number in recursive inclusion error message
  Coccinelle: memdup: Fix typo in warning messages
  kconfig: Update ncurses package names for menuconfig
  kbuild/kallsyms: trivial typo fix
  kbuild: test --build-id linker flag by ld-option instead of cc-ldoption
  kbuild: drop superfluous GCC_PLUGINS_CFLAGS assignment
  kconfig: Don't leak choice names during parsing
  sh: fix build error for empty CONFIG_BUILTIN_DTB_SOURCE
  kconfig: set SYMBOL_AUTO to the symbol marked with defconfig_list
  kconfig: add xstrdup() helper
  kbuild: disable sparse warnings about unknown attributes
  Makefile: Fix lying comment re. silentoldconfig

Pull media fixes from Mauro Carvalho Chehab:

  - some build fixes with randconfigs

  - an m88ds3103 fix to prevent an OOPS if the chip doesn't provide the
    right version during probe (with can happen if the hardware hangs)

  - a potential out of array bounds reference in tvp5150

  - some fixes and improvements in the DVB memory mapped API (added for
    kernel 4.16)

* tag 'media/v4.16-3' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media:
  media: vb2: Makefile: place vb2-trace together with vb2-core
  media: Don't let tvp5150_get_vbi() go out of vbi_ram_default array
  media: dvb: update buffer mmaped flags and frame counter
  media: dvb: add continuity error indicators for memory mapped buffers
  media: dmxdev: Fix the logic that enables DMA mmap support
  media: dmxdev: fix error code for invalid ioctls
  media: m88ds3103: don't call a non-initalized function
  media: au0828: add VIDEO_V4L2 dependency
  media: dvb: fix DVB_MMAP dependency
  media: dvb: fix DVB_MMAP symbol name
  media: videobuf2: fix build issues with vb2-trace
  media: videobuf2: Add VIDEOBUF2_V4L2 Kconfig option for VB2 V4L2 part

Pull watchdog fixes from Wim Van Sebroeck:

 - rave-sp: add NVMEM dependency

 - build fixes for i6300esb_wdt, xen_wdt and sp5100_tco

* tag 'linux-watchdog-4.16-fixes-1' of git://www.linux-watchdog.org/linux-watchdog:
  watchdog: sp5100_tco.c: fix potential build failure
  watchdog: xen_wdt: fix potential build failure
  watchdog: i6300esb: fix build failure
  watchdog: rave-sp: add NVMEM dependency

Pull KVM fixes from Radim Krčmář:
 "x86:

   - fix NULL dereference when using userspace lapic

   - optimize spectre v1 mitigations by allowing guests to use LFENCE

   - make microcode revision configurable to prevent guests from
     unnecessarily blacklisting spectre v2 mitigation feature"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86: fix vcpu initialization with userspace lapic
  KVM: X86: Allow userspace to define the microcode version
  KVM: X86: Introduce kvm_get_msr_feature()
  KVM: SVM: Add MSR-based feature support for serializing LFENCE
  KVM: x86: Add a framework for supporting MSR-based features

The cond_resched() currently in the setup path needs to be duplicated in
the teardown path. Rather than require each instance of
for_each_device_pfn() to open code the same sequence, embed it in the
helper.

Link: https://github.com/intel/ixpdimm_sw/issues/11
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: <stable@vger.kernel.org>
Fixes: 71389703 ("mm, zone_device: Replace {get, put}_zone_device_page()...")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Re-enable deep flush so that users always have a way to be sure that a
write makes it all the way out to media. Writes from the PMEM driver
always arrive at the NVDIMM since movnt is used to bypass the cache, and
the driver relies on the ADR (Asynchronous DRAM Refresh) mechanism to
flush write buffers on power failure. The Deep Flush mechanism is there
to explicitly write buffers to protect against (rare) ADR failure.  This
change prevents a regression in deep flush behavior so that applications
can continue to depend on fsync() as a mechanism to trigger deep flush
in the filesystem-DAX case.

Fixes: 06e8ccda ("acpi: nfit: Add support for detect platform CPU cache...")
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

I have recently picked up Kconfig patches to my tree without any
declaration.  Making it official now.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>

Filesystem-DAX is incompatible with 'longterm' page pinning. Without
page cache indirection a DAX mapping maps filesystem blocks directly.
This means that the filesystem must not modify a file's block map while
any page in a mapping is pinned. In order to prevent the situation of
userspace holding of filesystem operations indefinitely, disallow
'longterm' Filesystem-DAX mappings.

RDMA has the same conflict and the plan there is to add a 'with lease'
mechanism to allow the kernel to notify userspace that the mapping is
being torn down for block-map maintenance. Perhaps something similar can
be put in place for vfio.

Note that xfs and ext4 still report:

   "DAX enabled. Warning: EXPERIMENTAL, use at your own risk"

...at mount time, and resolving the dax-dma-vs-truncate problem is one
of the last hurdles to remove that designation.
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: kvm@vger.kernel.org
Cc: <stable@vger.kernel.org>
Reported-by: Haozhong Zhang <haozhong.zhang@intel.com>
Tested-by: Haozhong Zhang <haozhong.zhang@intel.com>
Fixes: d475c634 ("dax,ext2: replace XIP read and write with DAX I/O")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>