... because this is exactly what it is: the number of entries in the
LDT. Calling it "size" is simply confusing and it is actually begging
to be called "nr_entries" or somesuch, especially if you see constructs
like:

	alloc_size = size * LDT_ENTRY_SIZE;

since LDT_ENTRY_SIZE is the size of a single entry.

There should be no functionality change resulting from this patch, as
the before/after output from tools/testing/selftests/x86/ldt_gdt.c
shows.
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170606173116.13977-1-bp@alien8.de
[ Renamed 'n_entries' to 'nr_entries' ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

This fixes CONFIG_SMP=n, CONFIG_DEBUG_TLBFLUSH=y without introducing
further #ifdef soup.  Caught by a Kbuild bot randconfig build.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: ce4a4e56 ("x86/mm: Remove the UP asm/tlbflush.h code, always use the (formerly) SMP code")
Link: http://lkml.kernel.org/r/76da9a3cc4415996f2ad2c905b93414add322021.1496673616.git.luto@kernel.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>

When PCID is enabled, CR3's PCID bits can change during context
switches, so KVM won't be able to treat CR3 as a per-mm constant any
more.

I structured this like the existing CR4 handling.  Under ordinary
circumstances (PCID disabled or if the current PCID and the value
that's already in the VMCS match), then we won't do an extra VMCS
write, and we'll never do an extra direct CR3 read.  The overhead
should be minimal.

I disallowed using the new helper in non-atomic context because
PCID support will cause CR3 to stop being constant in non-atomic
process context.

(Frankly, it also scares me a bit that KVM ever treated CR3 as
constant, but it looks like it was okay before.)
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm@vger.kernel.org
Cc: linux-mm@kvack.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Nadav pointed out that some code used PAGE_SIZE and other code used
PAGE_SHIFT.  Use PAGE_SHIFT instead of multiplying or dividing by
PAGE_SIZE.
Requested-by: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Lazy TLB state is currently managed in a rather baroque manner.
AFAICT, there are three possible states:

 - Non-lazy.  This means that we're running a user thread or a
   kernel thread that has called use_mm().  current->mm ==
   current->active_mm == cpu_tlbstate.active_mm and
   cpu_tlbstate.state == TLBSTATE_OK.

 - Lazy with user mm.  We're running a kernel thread without an mm
   and we're borrowing an mm_struct.  We have current->mm == NULL,
   current->active_mm == cpu_tlbstate.active_mm, cpu_tlbstate.state
   != TLBSTATE_OK (i.e. TLBSTATE_LAZY or 0).  The current cpu is set
   in mm_cpumask(current->active_mm).  CR3 points to
   current->active_mm->pgd.  The TLB is up to date.

 - Lazy with init_mm.  This happens when we call leave_mm().  We
   have current->mm == NULL, current->active_mm ==
   cpu_tlbstate.active_mm, but that mm is only relelvant insofar as
   the scheduler is tracking it for refcounting.  cpu_tlbstate.state
   != TLBSTATE_OK.  The current cpu is clear in
   mm_cpumask(current->active_mm).  CR3 points to swapper_pg_dir,
   i.e. init_mm->pgd.

This patch simplifies the situation.  Other than perf, x86 stops
caring about current->active_mm at all.  We have
cpu_tlbstate.loaded_mm pointing to the mm that CR3 references.  The
TLB is always up to date for that mm.  leave_mm() just switches us
to init_mm.  There are no longer any special cases for mm_cpumask,
and switch_mm() switches mms without worrying about laziness.

After this patch, cpu_tlbstate.state serves only to tell the TLB
flush code whether it may switch to init_mm instead of doing a
normal flush.

This makes fairly extensive changes to xen_exit_mmap(), which used
to look a bit like black magic.

Perf is unchanged.  With or without this change, perf may behave a bit
erratically if it tries to read user memory in kernel thread context.
We should build on this patch to teach perf to never look at user
memory when cpu_tlbstate.loaded_mm != current->mm.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

The UP asm/tlbflush.h generates somewhat nicer code than the SMP version.
Aside from that, it's fallen quite a bit behind the SMP code:

 - flush_tlb_mm_range() didn't flush individual pages if the range
   was small.

 - The lazy TLB code was much weaker.  This usually wouldn't matter,
   but, if a kernel thread flushed its lazy "active_mm" more than
   once (due to reclaim or similar), it wouldn't be unlazied and
   would instead pointlessly flush repeatedly.

 - Tracepoints were missing.

Aside from that, simply having the UP code around was a maintanence
burden, since it means that any change to the TLB flush code had to
make sure not to break it.

Simplify everything by deleting the UP code.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Now there's only one copy of the local tlb flush logic for
non-kernel pages on SMP kernels.

The only functional change is that arch_tlbbatch_flush() will now
leave_mm() on the local CPU if that CPU is in the batch and is in
TLBSTATE_LAZY mode.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

The local flush path is very similar to the remote flush path.
Merge them.

This is intended to make no difference to behavior whatsoever.  It
removes some code and will make future changes to the flushing
mechanics simpler.

This patch does remove one small optimization: flush_tlb_mm_range()
now has an unconditional smp_mb() instead of using MOV to CR3 or
INVLPG as a full barrier when applicable.  I think this is okay for
a few reasons.  First, smp_mb() is quite cheap compared to the cost
of a TLB flush.  Second, this rearrangement makes a bigger
optimization available: with some work on the SMP function call
code, we could do the local and remote flushes in parallel.  Third,
I'm planning a rework of the TLB flush algorithm that will require
an atomic operation at the beginning of each flush, and that
operation will replace the smp_mb().
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

On a remote TLB flush, we leave_mm() if we're TLBSTATE_LAZY.  For a
local flush_tlb_mm_range(), we leave_mm() if !current->mm.  These
are approximately the same condition -- the scheduler sets lazy TLB
mode when switching to a thread with no mm.

I'm about to merge the local and remote flush code, but for ease of
verifying and bisecting the patch, I want the local and remote flush
behavior to match first.  This patch changes the local code to match
the remote code.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Rather than passing all the contents of flush_tlb_info to
flush_tlb_others(), pass a pointer to the structure directly. For
consistency, this also removes the unnecessary cpu parameter from
uv_flush_tlb_others() to make its signature match the other
*flush_tlb_others() functions.

This serves two purposes:

 - It will dramatically simplify future patches that change struct
   flush_tlb_info, which I'm planning to do.

 - struct flush_tlb_info is an adequate description of what to do
   for a local flush, too, so by reusing it we can remove duplicated
   code between local and remove flushes in a future patch.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
[ Fix build warning. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Signed-off-by: Ingo Molnar <mingo@kernel.org>

This fixes a problem with reading files larger than 2GB from a UFS-2
file system:

    https://bugzilla.kernel.org/show_bug.cgi?id=195721

The incorrect UFS s_maxsize limit became a problem as of commit
c2a9737f ("vfs,mm: fix a dead loop in truncate_inode_pages_range()")
which started using s_maxbytes to avoid a page index overflow in
do_generic_file_read().

That caused files to be truncated on UFS-2 file systems because the
default maximum file size is 2GB (MAX_NON_LFS) and UFS didn't update it.

Here I simply increase the default to a common value used by other file
systems.
Signed-off-by: Richard Narron <comet.berkeley@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Will B <will.brokenbourgh2877@gmail.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: <stable@vger.kernel.org> # v4.9 and backports of c2a9737fSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull NFS client bugfixes from Trond Myklebust:
 "Bugfixes include:

   - Fix a typo in commit e0926934 ("NFS append COMMIT after
     synchronous COPY") that breaks copy offload

   - Fix the connect error propagation in xs_tcp_setup_socket()

   - Fix a lock leak in nfs40_walk_client_list

   - Verify that pNFS requests lie within the offset range of the layout
     segment"

* tag 'nfs-for-4.12-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  nfs: Mark unnecessarily extern functions as static
  SUNRPC: ensure correct error is reported by xs_tcp_setup_socket()
  NFSv4.0: Fix a lock leak in nfs40_walk_client_list
  pnfs: Fix the check for requests in range of layout segment
  xprtrdma: Delete an error message for a failed memory allocation in xprt_rdma_bc_setup()
  pNFS/flexfiles: missing error code in ff_layout_alloc_lseg()
  NFS fix COMMIT after COPY

Pull tty fix from Greg KH:
 "Here is a single tty core fix for 4.12-rc4. It reverts a patch that a
  lot of people reported as causing lockdep and other warnings.

  Right after I reverted this in my tree, it seems like another
  "correct" fix might have shown up, but it's too late in the release
  cycle to be messing with tty core locking, so let's just revert this
  for now to go back how things always have been and try it again for
  4.13.

  This has not been in linux-next as I only reverted it a few hours ago"

* tag 'tty-4.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  Revert "tty: fix port buffer locking"

Pull input subsystem fixes from Dmitry Torokhov:

 - a couple of regression fixes in synaptics and axp20x-pek drivers

 - try to ease transition from PS/2 to RMI for Synaptics touchpad users
   by ensuring we do not try to activate RMI mode when RMI SMBus support
   is not enabled, and nag users a bit to enable it

 - plus a couple of other changes that seemed worthwhile for this
   release

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: axp20x-pek - switch to acpi_dev_present and check for ACPI0011 too
  Input: axp20x-pek - only check for "INTCFD9" ACPI device on Cherry Trail
  Input: tm2-touchkey - use LEN_ON as boolean value instead of LED_FULL
  Input: synaptics - tell users to report when they should be using rmi-smbus
  Input: synaptics - warn the users when there is a better mode
  Input: synaptics - keep PS/2 around when RMI4_SMB is not enabled
  Input: synaptics - clear device info before filling in
  Input: silead - disable interrupt during suspend

Pull RTC fixlet from Alexandre Belloni:
 "A single patch, not really a fix but I don't think there is any reason
  to delay it.

  Change the mailing list address"

* tag 'rtc-4.12-2' of git://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux:
  MAINTAINERS: update RTC mailing list

Pull SCSI fixes from James Bottomley:
 "This is nine fixes, seven of which are for the qedi driver (new as of
  4.10) the other two are a use after free in the cxgbi drivers and a
  potential NULL dereference in the rdac device handler"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: libcxgbi: fix skb use after free
  scsi: qedi: Fix endpoint NULL panic during recovery.
  scsi: qedi: set max_fin_rt default value
  scsi: qedi: Set firmware tcp msl timer value.
  scsi: qedi: Fix endpoint NULL panic in qedi_set_path.
  scsi: qedi: Set dma_boundary to 0xfff.
  scsi: qedi: Correctly set firmware max supported BDs.
  scsi: qedi: Fix bad pte call trace when iscsiuio is stopped.
  scsi: scsi_dh_rdac: Use ctlr directly in rdac_failover_get()

Pull rdma fixes from Doug Ledford:
 "For the most part this is just a minor -rc cycle for the rdma
  subsystem. Even given that this is all of the -rc patches since the
  merge window closed, it's still only about 25 patches:

   - Multiple i40iw, nes, iw_cxgb4, hfi1, qib, mlx4, mlx5 fixes

   - A few upper layer protocol fixes (IPoIB, iSER, SRP)

   - A modest number of core fixes"

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma: (26 commits)
  RDMA/SA: Fix kernel panic in CMA request handler flow
  RDMA/umem: Fix missing mmap_sem in get umem ODP call
  RDMA/core: not to set page dirty bit if it's already set.
  RDMA/uverbs: Declare local function static and add brackets to sizeof
  RDMA/netlink: Reduce exposure of RDMA netlink functions
  RDMA/srp: Fix NULL deref at srp_destroy_qp()
  RDMA/IPoIB: Limit the ipoib_dev_uninit_default scope
  RDMA/IPoIB: Replace netdev_priv with ipoib_priv for ipoib_get_link_ksettings
  RDMA/qedr: add null check before pointer dereference
  RDMA/mlx5: set UMR wqe fence according to HCA cap
  net/mlx5: Define interface bits for fencing UMR wqe
  RDMA/mlx4: Fix MAD tunneling when SRIOV is enabled
  RDMA/qib,hfi1: Fix MR reference count leak on write with immediate
  RDMA/hfi1: Defer setting VL15 credits to link-up interrupt
  RDMA/hfi1: change PCI bar addr assignments to Linux API functions
  RDMA/hfi1: fix array termination by appending NULL to attr array
  RDMA/iw_cxgb4: fix the calculation of ipv6 header size
  RDMA/iw_cxgb4: calculate t4_eq_status_entries properly
  RDMA/iw_cxgb4: Avoid touch after free error in ARP failure handlers
  RDMA/nes: ACK MPA Reply frame
  ...

This reverts commit 925bb1ce.

It causes lots of warnings and problems so for now, let's just revert
it.

Reported-by: <valdis.kletnieks@vt.edu>
Reported-by: Russell King <linux@armlinux.org.uk>
Reported-by: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reported-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

nfs_initialise_sb() and nfs_clone_super() are declared as extern even
though they are used only in fs/nfs/super.c. Mark them as static.

Also remove explicit 'inline' directive from nfs_initialise_sb() and
leave it upto compiler to decide whether inlining is worth it.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

Merge tag 'hwmon-for-linus-v4.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging

Pull hwmon fixes from Guenter Roeck:
 "A couple of patches for the aspeed pwm fan driver"

* tag 'hwmon-for-linus-v4.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
  hwmon: (aspeed-pwm-tacho) make fan/pwm names start with index 1
  hwmon: (aspeed-pwm-tacho) Call of_node_put() on a node not claimed
  hwmon: (aspeed-pwm-tacho) On read failure return -ETIMEDOUT
  hwmon: (aspeed-pwm-tacho) Select REGMAP

Pull MTD fixes from Brian Norris:
 "NAND updates from Boris:

  tango fixes:
   - Add missing MODULE_DEVICE_TABLE() in tango_nand.c
   - Update the number of corrected bitflips

  core fixes:
   - Fix a long standing memory leak in nand_scan_tail()
   - Fix several bugs introduced by the per-vendor init/detection
     infrastructure (introduced in 4.12)
   - Add a static specifier to nand_ooblayout_lp_hamming_ops definition"

* tag 'for-linus-20170602' of git://git.infradead.org/linux-mtd:
  mtd: nand: make nand_ooblayout_lp_hamming_ops static
  mtd: nand: tango: Update ecc_stats.corrected
  mtd: nand: tango: Export OF device ID table as module aliases
  mtd: nand: samsung: warn about un-parseable ECC info
  mtd: nand: free vendor-specific resources in init failure paths
  mtd: nand: drop unneeded module.h include
  mtd: nand: don't leak buffers when ->scan_bbt() fails

Make fan and pwm names in sysfs start with index 1 in accordance to
Documentation/hwmon/sysfs-interface conventions.

Current implementation starts with index 0, making tools such as
sensors(1) skip the first fan.
Signed-off-by: Stefan Schaeckeler <sschaeck@cisco.com>
Fixes: 2d7a548a ("drivers: hwmon: Support for ASPEED PWM/Fan tach")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Call of_node_put() on a node claimed with of_node_get() or by any other
means such as for_each_child_of_node().
Signed-off-by: Stefan Schaeckeler <sschaeck@cisco.com>
Fixes: 2d7a548a ("drivers: hwmon: Support for ASPEED PWM/Fan tach")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

acpi_dev_found checks that there is a matching ACPI node, but it
may be disabled (_STA method returns 0) in which case the
soc_button_array driver will not bind to it and axp20x-pek should
handle the power-button.

This commit switches from acpi_dev_found to acpi_dev_present to
avoid not registering an input-dev for the powerbutton when there
is a disabled PNP0C40 device.

The ACPI-6.0 standard defines a standard gpio button device using
the ACPI0011 HID replacing the custom PNP0C40 gpio device, many
newer devices define both PNP0C40 and ACPI0011 devices enabling one
or the other depending on whether the BIOS thinks it is going to boot
Android or Windows.

This commit adds a check for the ACPI0011 device, so that if
either device is present *and* enabled we don't register an input-dev
for the powerbutton.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Commit 9b13a4ca ("Input: axp20x-pek - do not register input device
on some systems") added a check for the INTCFD9 ACPI device which also
handles the powerbutton as on some systems the powerbutton is connected
to both the PMIC, handled by axp20x-pek, and to a gpio on the SoC, handled
by soc_button_array which attaches itself to the INTCFD9 ACPI device.

Testing + comparing DSDTs has shown that this only happens on Cherry
Trail devices with an AXP288 PMIC, the AXP288 PMIC is also used on
Bay Trail devices but there the power button is only connected to
the PMIC and not handled by soc_button_array.

This means that the INTCFD9 check has caused a regression on Bay Trail
devices, causing power-button presses to no longer be seen.

This commit fixes this by limiting the check to devices where the ACPI
node for the AXP288 contains a _HRV (hardware revision) attribute with
a value of 3 which indicates we are dealing with a Cherry Trail platform.

Fixes: 9b13a4ca ("Input: axp20x-pek - do not register input ...")
Reported-by: Сергей Трусов <t.rus76@ya.ru>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Merge with mainline to get acpi_dev_present() needed by patches to
axp20x-pek driver.

Pull ACPI fixes from Rafael Wysocki:
 "These revert one more problematic commit related to the ACPI-based
  handling of laptop lids and make some unuseful error messages coming
  from ACPICA go away.

  Specifics:

   - Revert one more commit related to the ACPI-based handling of laptop
     lids that changed the default behavior on laptops that booted with
     closed lids and introduced a regression there (Benjamin Tissoires).

   - Add a missing acpi_put_table() to the code implementing the
     /sys/firmware/acpi/tables interface to prevent a counter in the
     ACPICA core from overflowing (Dan Williams).

   - Drop error messages printed by ACPICA on acpi_get_table() reference
     counting mismatches as they need not indicate real errors at this
     point (Lv Zheng)"

* tag 'acpi-4.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPICA: Tables: Fix regression introduced by a too early mechanism enabling
  Revert "ACPI / button: Change default behavior to lid_init_state=open"
  ACPI / sysfs: fix acpi_get_table() leak / acpi-sysfs denial of service

Pull power management fixes from Rafael Wysocki:
 "These fix two bugs in error code paths in the cpufreq core and in the
  kirkwood-cpufreq driver.

  Specifics:

   - Make cpufreq_register_driver() return an error if the ->init()
     calls fail for all CPUs to prevent non-functional drivers from
     hanging around for no reason (David Arcari).

   - Make kirkwood-cpufreq check the return value of
     clk_prepare_enable() (which may fail) as appropriate (Arvind
     Yadav)"

* tag 'pm-4.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  cpufreq: kirkwood-cpufreq:- Handle return value of clk_prepare_enable()
  cpufreq: cpufreq_register_driver() should return -ENODEV if init fails

Pull /dev/random bug fix from Ted Ts'o:
 "Fix a race on architectures with prioritized interrupts (such as m68k)
  which can causes crashes in drivers/char/random.c:get_reg()"

* tag 'random_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
  fix race in drivers/char/random.c:get_reg()

Merge misc fixes from Andrew Morton:
 "15 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  scripts/gdb: make lx-dmesg command work (reliably)
  mm: consider memblock reservations for deferred memory initialization sizing
  mm/hugetlb: report -EHWPOISON not -EFAULT when FOLL_HWPOISON is specified
  mlock: fix mlock count can not decrease in race condition
  mm/migrate: fix refcount handling when !hugepage_migration_supported()
  dax: fix race between colliding PMD & PTE entries
  mm: avoid spurious 'bad pmd' warning messages
  mm/page_alloc.c: make sure OOM victim can try allocations with no watermarks once
  pcmcia: remove left-over %Z format
  slub/memcg: cure the brainless abuse of sysfs attributes
  initramfs: fix disabling of initramfs (and its compression)
  mm: clarify why we want kmalloc before falling backto vmallock
  frv: declare jiffies to be located in the .data section
  include/linux/gfp.h: fix ___GFP_NOLOCKDEP value
  ksm: prevent crash after write_protect_page fails

lx-dmesg needs access to the log_buf symbol from printk.c.
Unfortunately, the symbol log_buf also exists in BPF's verifier.c and
hence gdb can pick one or the other.  If it happens to pick BPF's
log_buf, lx-dmesg doesn't work:

  (gdb) lx-dmesg
  Python Exception <class 'gdb.MemoryError'> Cannot access memory at address 0x0:
  Error occurred in Python command: Cannot access memory at address 0x0
  (gdb) p log_buf
  $15 = 0x0

Luckily, GDB has a way to deal with this, see
  https://sourceware.org/gdb/onlinedocs/gdb/Symbols.html

  (gdb) info variables ^log_buf$
  All variables matching regular expression "^log_buf$":

  File <linux.git>/kernel/bpf/verifier.c:
  static char *log_buf;

  File <linux.git>/kernel/printk/printk.c:
  static char *log_buf;
  (gdb) p 'verifier.c'::log_buf
  $1 = 0x0
  (gdb) p 'printk.c'::log_buf
  $2 = 0x811a6aa0 <__log_buf> ""
  (gdb) p &log_buf
  $3 = (char **) 0x8120fe40 <log_buf>
  (gdb) p &'verifier.c'::log_buf
  $4 = (char **) 0x8120fe40 <log_buf>
  (gdb) p &'printk.c'::log_buf
  $5 = (char **) 0x8048b7d0 <log_buf>

By being explicit about the location of the symbol, we can make lx-dmesg
work again.  While at it, do the same for the other symbols we need from
printk.c

Link: http://lkml.kernel.org/r/20170526112222.3414-1-git@andred.netSigned-off-by: André Draszik <git@andred.net>
Tested-by: Kieran Bingham <kieran@bingham.xyz>
Acked-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We have seen an early OOM killer invocation on ppc64 systems with
crashkernel=4096M:

	kthreadd invoked oom-killer: gfp_mask=0x16040c0(GFP_KERNEL|__GFP_COMP|__GFP_NOTRACK), nodemask=7, order=0, oom_score_adj=0
	kthreadd cpuset=/ mems_allowed=7
	CPU: 0 PID: 2 Comm: kthreadd Not tainted 4.4.68-1.gd7fe927-default #1
	Call Trace:
	  dump_stack+0xb0/0xf0 (unreliable)
	  dump_header+0xb0/0x258
	  out_of_memory+0x5f0/0x640
	  __alloc_pages_nodemask+0xa8c/0xc80
	  kmem_getpages+0x84/0x1a0
	  fallback_alloc+0x2a4/0x320
	  kmem_cache_alloc_node+0xc0/0x2e0
	  copy_process.isra.25+0x260/0x1b30
	  _do_fork+0x94/0x470
	  kernel_thread+0x48/0x60
	  kthreadd+0x264/0x330
	  ret_from_kernel_thread+0x5c/0xa4

	Mem-Info:
	active_anon:0 inactive_anon:0 isolated_anon:0
	 active_file:0 inactive_file:0 isolated_file:0
	 unevictable:0 dirty:0 writeback:0 unstable:0
	 slab_reclaimable:5 slab_unreclaimable:73
	 mapped:0 shmem:0 pagetables:0 bounce:0
	 free:0 free_pcp:0 free_cma:0
	Node 7 DMA free:0kB min:0kB low:0kB high:0kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:52428800kB managed:110016kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:320kB slab_unreclaimable:4672kB kernel_stack:1152kB pagetables:0kB unstable:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? yes
	lowmem_reserve[]: 0 0 0 0
	Node 7 DMA: 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB 0*8192kB 0*16384kB = 0kB
	0 total pagecache pages
	0 pages in swap cache
	Swap cache stats: add 0, delete 0, find 0/0
	Free swap  = 0kB
	Total swap = 0kB
	819200 pages RAM
	0 pages HighMem/MovableOnly
	817481 pages reserved
	0 pages cma reserved
	0 pages hwpoisoned

the reason is that the managed memory is too low (only 110MB) while the
rest of the the 50GB is still waiting for the deferred intialization to
be done.  update_defer_init estimates the initial memoty to initialize
to 2GB at least but it doesn't consider any memory allocated in that
range.  In this particular case we've had

	Reserving 4096MB of memory at 128MB for crashkernel (System RAM: 51200MB)

so the low 2GB is mostly depleted.

Fix this by considering memblock allocations in the initial static
initialization estimation.  Move the max_initialise to
reset_deferred_meminit and implement a simple memblock_reserved_memory
helper which iterates all reserved blocks and sums the size of all that
start below the given address.  The cumulative size is than added on top
of the initial estimation.  This is still not ideal because
reset_deferred_meminit doesn't consider holes and so reservation might
be above the initial estimation whihch we ignore but let's make the
logic simpler until we really need to handle more complicated cases.

Fixes: 3a80a7fa ("mm: meminit: initialise a subset of struct pages if CONFIG_DEFERRED_STRUCT_PAGE_INIT is set")
Link: http://lkml.kernel.org/r/20170531104010.GI27783@dhcp22.suse.czSigned-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Tested-by: Srikar Dronamraju <srikar@linux.vnet.ibm.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>

KVM uses get_user_pages() to resolve its stage2 faults.  KVM sets the
FOLL_HWPOISON flag causing faultin_page() to return -EHWPOISON when it
finds a VM_FAULT_HWPOISON.  KVM handles these hwpoison pages as a
special case.  (check_user_page_hwpoison())

When huge pages are involved, this doesn't work so well.
get_user_pages() calls follow_hugetlb_page(), which stops early if it
receives VM_FAULT_HWPOISON from hugetlb_fault(), eventually returning
-EFAULT to the caller.  The step to map this to -EHWPOISON based on the
FOLL_ flags is missing.  The hwpoison special case is skipped, and
-EFAULT is returned to user-space, causing Qemu or kvmtool to exit.

Instead, move this VM_FAULT_ to errno mapping code into a header file
and use it from faultin_page() and follow_hugetlb_page().

With this, KVM works as expected.

This isn't a problem for arm64 today as we haven't enabled
MEMORY_FAILURE, but I can't see any reason this doesn't happen on x86
too, so I think this should be a fix.  This doesn't apply earlier than
stable's v4.11.1 due to all sorts of cleanup.

[james.morse@arm.com: add vm_fault_to_errno() call to faultin_page()]
suggested.
  Link: http://lkml.kernel.org/r/20170525171035.16359-1-james.morse@arm.com
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170524160900.28786-1-james.morse@arm.comSigned-off-by: James Morse <james.morse@arm.com>
Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: <stable@vger.kernel.org>	[4.11.1+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Kefeng reported that when running the follow test, the mlock count in
meminfo will increase permanently:

 [1] testcase
 linux:~ # cat test_mlockal
 grep Mlocked /proc/meminfo
  for j in `seq 0 10`
  do
 	for i in `seq 4 15`
 	do
 		./p_mlockall >> log &
 	done
 	sleep 0.2
 done
 # wait some time to let mlock counter decrease and 5s may not enough
 sleep 5
 grep Mlocked /proc/meminfo

 linux:~ # cat p_mlockall.c
 #include <sys/mman.h>
 #include <stdlib.h>
 #include <stdio.h>

 #define SPACE_LEN	4096

 int main(int argc, char ** argv)
 {
	 	int ret;
	 	void *adr = malloc(SPACE_LEN);
	 	if (!adr)
	 		return -1;

	 	ret = mlockall(MCL_CURRENT | MCL_FUTURE);
	 	printf("mlcokall ret = %d\n", ret);

	 	ret = munlockall();
	 	printf("munlcokall ret = %d\n", ret);

	 	free(adr);
	 	return 0;
	 }

In __munlock_pagevec() we should decrement NR_MLOCK for each page where
we clear the PageMlocked flag.  Commit 1ebb7cc6 ("mm: munlock: batch
NR_MLOCK zone state updates") has introduced a bug where we don't
decrement NR_MLOCK for pages where we clear the flag, but fail to
isolate them from the lru list (e.g.  when the pages are on some other
cpu's percpu pagevec).  Since PageMlocked stays cleared, the NR_MLOCK
accounting gets permanently disrupted by this.

Fix it by counting the number of page whose PageMlock flag is cleared.

Fixes: 1ebb7cc6 (" mm: munlock: batch NR_MLOCK zone state updates")
Link: http://lkml.kernel.org/r/1495678405-54569-1-git-send-email-xieyisheng1@huawei.comSigned-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Reported-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Joern Engel <joern@logfs.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michel Lespinasse <walken@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: zhongjiang <zhongjiang@huawei.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

On failing to migrate a page, soft_offline_huge_page() performs the
necessary update to the hugepage ref-count.

But when !hugepage_migration_supported() , unmap_and_move_hugepage()
also decrements the page ref-count for the hugepage.  The combined
behaviour leaves the ref-count in an inconsistent state.

This leads to soft lockups when running the overcommitted hugepage test
from mce-tests suite.

  Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
  soft offline: 0x83ed600: migration failed 1, type 1fffc00000008008 (uptodate|head)
  INFO: rcu_preempt detected stalls on CPUs/tasks:
   Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
    (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
    thugetlb_overco R  running task        0  2715   2685 0x00000008
    Call trace:
      dump_backtrace+0x0/0x268
      show_stack+0x24/0x30
      sched_show_task+0x134/0x180
      rcu_print_detail_task_stall_rnp+0x54/0x7c
      rcu_check_callbacks+0xa74/0xb08
      update_process_times+0x34/0x60
      tick_sched_handle.isra.7+0x38/0x70
      tick_sched_timer+0x4c/0x98
      __hrtimer_run_queues+0xc0/0x300
      hrtimer_interrupt+0xac/0x228
      arch_timer_handler_phys+0x3c/0x50
      handle_percpu_devid_irq+0x8c/0x290
      generic_handle_irq+0x34/0x50
      __handle_domain_irq+0x68/0xc0
      gic_handle_irq+0x5c/0xb0

Address this by changing the putback_active_hugepage() in
soft_offline_huge_page() to putback_movable_pages().

This only triggers on systems that enable memory failure handling
(ARCH_SUPPORTS_MEMORY_FAILURE) but not hugepage migration
(!ARCH_ENABLE_HUGEPAGE_MIGRATION).

I imagine this wasn't triggered as there aren't many systems running
this configuration.

[akpm@linux-foundation.org: remove dead comment, per Naoya]
Link: http://lkml.kernel.org/r/20170525135146.32011-1-punit.agrawal@arm.comReported-by: Manoj Iyer <manoj.iyer@canonical.com>
Tested-by: Manoj Iyer <manoj.iyer@canonical.com>
Suggested-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: <stable@vger.kernel.org>	[3.14+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We currently have two related PMD vs PTE races in the DAX code.  These
can both be easily triggered by having two threads reading and writing
simultaneously to the same private mapping, with the key being that
private mapping reads can be handled with PMDs but private mapping
writes are always handled with PTEs so that we can COW.

Here is the first race:

  CPU 0					CPU 1

  (private mapping write)
  __handle_mm_fault()
    create_huge_pmd() - FALLBACK
    handle_pte_fault()
      passes check for pmd_devmap()

					(private mapping read)
					__handle_mm_fault()
					  create_huge_pmd()
					    dax_iomap_pmd_fault() inserts PMD

      dax_iomap_pte_fault() does a PTE fault, but we already have a DAX PMD
      			  installed in our page tables at this spot.

Here's the second race:

  CPU 0					CPU 1

  (private mapping read)
  __handle_mm_fault()
    passes check for pmd_none()
    create_huge_pmd()
      dax_iomap_pmd_fault() inserts PMD

  (private mapping write)
  __handle_mm_fault()
    create_huge_pmd() - FALLBACK
					(private mapping read)
					__handle_mm_fault()
					  passes check for pmd_none()
					  create_huge_pmd()

    handle_pte_fault()
      dax_iomap_pte_fault() inserts PTE
					    dax_iomap_pmd_fault() inserts PMD,
					       but we already have a PTE at
					       this spot.

The core of the issue is that while there is isolation between faults to
the same range in the DAX fault handlers via our DAX entry locking,
there is no isolation between faults in the code in mm/memory.c.  This
means for instance that this code in __handle_mm_fault() can run:

	if (pmd_none(*vmf.pmd) && transparent_hugepage_enabled(vma)) {
		ret = create_huge_pmd(&vmf);

But by the time we actually get to run the fault handler called by
create_huge_pmd(), the PMD is no longer pmd_none() because a racing PTE
fault has installed a normal PMD here as a parent.  This is the cause of
the 2nd race.  The first race is similar - there is the following check
in handle_pte_fault():

	} else {
		/* See comment in pte_alloc_one_map() */
		if (pmd_devmap(*vmf->pmd) || pmd_trans_unstable(vmf->pmd))
			return 0;

So if a pmd_devmap() PMD (a DAX PMD) has been installed at vmf->pmd, we
will bail and retry the fault.  This is correct, but there is nothing
preventing the PMD from being installed after this check but before we
actually get to the DAX PTE fault handlers.

In my testing these races result in the following types of errors:

  BUG: Bad rss-counter state mm:ffff8800a817d280 idx:1 val:1
  BUG: non-zero nr_ptes on freeing mm: 15

Fix this issue by having the DAX fault handlers verify that it is safe
to continue their fault after they have taken an entry lock to block
other racing faults.

[ross.zwisler@linux.intel.com: improve fix for colliding PMD & PTE entries]
  Link: http://lkml.kernel.org/r/20170526195932.32178-1-ross.zwisler@linux.intel.com
Link: http://lkml.kernel.org/r/20170522215749.23516-2-ross.zwisler@linux.intel.comSigned-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reported-by: Pawel Lebioda <pawel.lebioda@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Pawel Lebioda <pawel.lebioda@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Xiong Zhou <xzhou@redhat.com>
Cc: Eryu Guan <eguan@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When the pmd_devmap() checks were added by 5c7fb56e ("mm, dax:
dax-pmd vs thp-pmd vs hugetlbfs-pmd") to add better support for DAX huge
pages, they were all added to the end of if() statements after existing
pmd_trans_huge() checks.  So, things like:

  -       if (pmd_trans_huge(*pmd))
  +       if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd))

When further checks were added after pmd_trans_unstable() checks by
commit 7267ec00 ("mm: postpone page table allocation until we have
page to map") they were also added at the end of the conditional:

  +       if (pmd_trans_unstable(fe->pmd) || pmd_devmap(*fe->pmd))

This ordering is fine for pmd_trans_huge(), but doesn't work for
pmd_trans_unstable().  This is because DAX huge pages trip the bad_pmd()
check inside of pmd_none_or_trans_huge_or_clear_bad() (called by
pmd_trans_unstable()), which prints out a warning and returns 1.  So, we
do end up doing the right thing, but only after spamming dmesg with
suspicious looking messages:

  mm/pgtable-generic.c:39: bad pmd ffff8808daa49b88(84000001006000a5)

Reorder these checks in a helper so that pmd_devmap() is checked first,
avoiding the error messages, and add a comment explaining why the
ordering is important.

Fixes: commit 7267ec00 ("mm: postpone page table allocation until we have page to map")
Link: http://lkml.kernel.org/r/20170522215749.23516-1-ross.zwisler@linux.intel.comSigned-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Pawel Lebioda <pawel.lebioda@intel.com>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Xiong Zhou <xzhou@redhat.com>
Cc: Eryu Guan <eguan@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Roman Gushchin has reported that the OOM killer can trivially selects
next OOM victim when a thread doing memory allocation from page fault
path was selected as first OOM victim.

    allocate invoked oom-killer: gfp_mask=0x14280ca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), nodemask=(null),  order=0, oom_score_adj=0
    allocate cpuset=/ mems_allowed=0
    CPU: 1 PID: 492 Comm: allocate Not tainted 4.12.0-rc1-mm1+ #181
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
    Call Trace:
     oom_kill_process+0x219/0x3e0
     out_of_memory+0x11d/0x480
     __alloc_pages_slowpath+0xc84/0xd40
     __alloc_pages_nodemask+0x245/0x260
     alloc_pages_vma+0xa2/0x270
     __handle_mm_fault+0xca9/0x10c0
     handle_mm_fault+0xf3/0x210
     __do_page_fault+0x240/0x4e0
     trace_do_page_fault+0x37/0xe0
     do_async_page_fault+0x19/0x70
     async_page_fault+0x28/0x30
    ...
    Out of memory: Kill process 492 (allocate) score 899 or sacrifice child
    Killed process 492 (allocate) total-vm:2052368kB, anon-rss:1894576kB, file-rss:4kB, shmem-rss:0kB
    allocate: page allocation failure: order:0, mode:0x14280ca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), nodemask=(null)
    allocate cpuset=/ mems_allowed=0
    CPU: 1 PID: 492 Comm: allocate Not tainted 4.12.0-rc1-mm1+ #181
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
    Call Trace:
     __alloc_pages_slowpath+0xd32/0xd40
     __alloc_pages_nodemask+0x245/0x260
     alloc_pages_vma+0xa2/0x270
     __handle_mm_fault+0xca9/0x10c0
     handle_mm_fault+0xf3/0x210
     __do_page_fault+0x240/0x4e0
     trace_do_page_fault+0x37/0xe0
     do_async_page_fault+0x19/0x70
     async_page_fault+0x28/0x30
    ...
    oom_reaper: reaped process 492 (allocate), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
    ...
    allocate invoked oom-killer: gfp_mask=0x0(), nodemask=(null),  order=0, oom_score_adj=0
    allocate cpuset=/ mems_allowed=0
    CPU: 1 PID: 492 Comm: allocate Not tainted 4.12.0-rc1-mm1+ #181
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
    Call Trace:
     oom_kill_process+0x219/0x3e0
     out_of_memory+0x11d/0x480
     pagefault_out_of_memory+0x68/0x80
     mm_fault_error+0x8f/0x190
     ? handle_mm_fault+0xf3/0x210
     __do_page_fault+0x4b2/0x4e0
     trace_do_page_fault+0x37/0xe0
     do_async_page_fault+0x19/0x70
     async_page_fault+0x28/0x30
    ...
    Out of memory: Kill process 233 (firewalld) score 10 or sacrifice child
    Killed process 233 (firewalld) total-vm:246076kB, anon-rss:20956kB, file-rss:0kB, shmem-rss:0kB

There is a race window that the OOM reaper completes reclaiming the
first victim's memory while nothing but mutex_trylock() prevents the
first victim from calling out_of_memory() from pagefault_out_of_memory()
after memory allocation for page fault path failed due to being selected
as an OOM victim.

This is a side effect of commit 9a67f648 ("mm: consolidate
GFP_NOFAIL checks in the allocator slowpath") because that commit
silently changed the behavior from

    /* Avoid allocations with no watermarks from looping endlessly */

to

    /*
     * Give up allocations without trying memory reserves if selected
     * as an OOM victim
     */

in __alloc_pages_slowpath() by moving the location to check TIF_MEMDIE
flag.  I have noticed this change but I didn't post a patch because I
thought it is an acceptable change other than noise by warn_alloc()
because !__GFP_NOFAIL allocations are allowed to fail.  But we
overlooked that failing memory allocation from page fault path makes
difference due to the race window explained above.

While it might be possible to add a check to pagefault_out_of_memory()
that prevents the first victim from calling out_of_memory() or remove
out_of_memory() from pagefault_out_of_memory(), changing
pagefault_out_of_memory() does not suppress noise by warn_alloc() when
allocating thread was selected as an OOM victim.  There is little point
with printing similar backtraces and memory information from both
out_of_memory() and warn_alloc().

Instead, if we guarantee that current thread can try allocations with no
watermarks once when current thread looping inside
__alloc_pages_slowpath() was selected as an OOM victim, we can follow "who
can use memory reserves" rules and suppress noise by warn_alloc() and
prevent memory allocations from page fault path from calling
pagefault_out_of_memory().

If we take the comment literally, this patch would do

  -    if (test_thread_flag(TIF_MEMDIE))
  -        goto nopage;
  +    if (alloc_flags == ALLOC_NO_WATERMARKS || (gfp_mask & __GFP_NOMEMALLOC))
  +        goto nopage;

because gfp_pfmemalloc_allowed() returns false if __GFP_NOMEMALLOC is
given.  But if I recall correctly (I couldn't find the message), the
condition is meant to apply to only OOM victims despite the comment.
Therefore, this patch preserves TIF_MEMDIE check.

Fixes: 9a67f648 ("mm: consolidate GFP_NOFAIL checks in the allocator slowpath")
Link: http://lkml.kernel.org/r/201705192112.IAF69238.OQOHSJLFOFFMtV@I-love.SAKURA.ne.jpSigned-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: Roman Gushchin <guro@fb.com>
Tested-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org>	[4.11]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>