Pull tracefs fixes from Steven Rostedt:
 "Al Viro has been looking at the tracefs code, and has pointed out some
  issues.  This contains one fix by me and one by Al.  I'm sure that
  he'll come up with more but for now I tested these patches and they
  don't appear to have any negative impact on tracing"

* tag 'trace-v4.8-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  fix memory leaks in tracing_buffers_splice_read()
  tracing: Move mutex to protect against resetting of seq data

When building XFS with -Werror, it now fails with:

  include/linux/pagemap.h: In function 'fault_in_multipages_readable':
  include/linux/pagemap.h:602:16: error: variable 'c' set but not used [-Werror=unused-but-set-variable]
    volatile char c;
                  ^

This is a regression caused by commit e23d4159b109 ("fix
fault_in_multipages_...() on architectures with no-op access_ok()").
Fix it by re-adding the "(void)c" trick taht was previously used to make
the compiler think the variable is used.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The NUMA balancing logic uses an arch-specific PROT_NONE page table flag
defined by pte_protnone() or pmd_protnone() to mark PTEs or huge page
PMDs respectively as requiring balancing upon a subsequent page fault.
User-defined PROT_NONE memory regions which also have this flag set will
not normally invoke the NUMA balancing code as do_page_fault() will send
a segfault to the process before handle_mm_fault() is even called.

However if access_remote_vm() is invoked to access a PROT_NONE region of
memory, handle_mm_fault() is called via faultin_page() and
__get_user_pages() without any access checks being performed, meaning
the NUMA balancing logic is incorrectly invoked on a non-NUMA memory
region.

A simple means of triggering this problem is to access PROT_NONE mmap'd
memory using /proc/self/mem which reliably results in the NUMA handling
functions being invoked when CONFIG_NUMA_BALANCING is set.

This issue was reported in bugzilla (issue 99101) which includes some
simple repro code.

There are BUG_ON() checks in do_numa_page() and do_huge_pmd_numa_page()
added at commit c0e7cad to avoid accidentally provoking strange
behaviour by attempting to apply NUMA balancing to pages that are in
fact PROT_NONE.  The BUG_ON()'s are consistently triggered by the repro.

This patch moves the PROT_NONE check into mm/memory.c rather than
invoking BUG_ON() as faulting in these pages via faultin_page() is a
valid reason for reaching the NUMA check with the PROT_NONE page table
flag set and is therefore not always a bug.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=99101
Reported-by: Trevor Saunders <tbsaunde@tbsaunde.org>
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull MIPS fixes from Ralf Baechle:
 "A round of 4.8 fixes:

  MIPS generic code:
   - Add a missing ".set pop" in an early commit
   - Fix memory regions reaching top of physical
   - MAAR: Fix address alignment
   - vDSO: Fix Malta EVA mapping to vDSO page structs
   - uprobes: fix incorrect uprobe brk handling
   - uprobes: select HAVE_REGS_AND_STACK_ACCESS_API
   - Avoid a BUG warning during PR_SET_FP_MODE prctl
   - SMP: Fix possibility of deadlock when bringing CPUs online
   - R6: Remove compact branch policy Kconfig entries
   - Fix size calc when avoiding IPIs for small icache flushes
   - Fix pre-r6 emulation FPU initialisation
   - Fix delay slot emulation count in debugfs

  ATH79:
   - Fix test for error return of clk_register_fixed_factor.

  Octeon:
   - Fix kernel header to work for VDSO build.
   - Fix initialization of platform device probing.

  paravirt:
   - Fix undefined reference to smp_bootstrap"

* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
  MIPS: Fix delay slot emulation count in debugfs
  MIPS: SMP: Fix possibility of deadlock when bringing CPUs online
  MIPS: Fix pre-r6 emulation FPU initialisation
  MIPS: vDSO: Fix Malta EVA mapping to vDSO page structs
  MIPS: Select HAVE_REGS_AND_STACK_ACCESS_API
  MIPS: Octeon: Fix platform bus probing
  MIPS: Octeon: mangle-port: fix build failure with VDSO code
  MIPS: Avoid a BUG warning during prctl(PR_SET_FP_MODE, ...)
  MIPS: c-r4k: Fix size calc when avoiding IPIs for small icache flushes
  MIPS: Add a missing ".set pop" in an early commit
  MIPS: paravirt: Fix undefined reference to smp_bootstrap
  MIPS: Remove compact branch policy Kconfig entries
  MIPS: MAAR: Fix address alignment
  MIPS: Fix memory regions reaching top of physical
  MIPS: uprobes: fix incorrect uprobe brk handling
  MIPS: ath79: Fix test for error return of clk_register_fixed_factor().

Pull one more powerpc fix from Michael Ellerman:
 "powernv/pci: Fix m64 checks for SR-IOV and window alignment from
  Russell Currey"

* tag 'powerpc-4.8-7' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/powernv/pci: Fix m64 checks for SR-IOV and window alignment

The fixes to the radix tree test suite show that the multi-order case is
broken.  The basic reason is that the radix tree code uses tagged
pointers with the "internal" bit in the low bits, and calculating the
pointer indices was supposed to mask off those bits.  But gcc will
notice that we then use the index to re-create the pointer, and will
avoid doing the arithmetic and use the tagged pointer directly.

This cleans the code up, using the existing is_sibling_entry() helper to
validate the sibling pointer range (instead of open-coding it), and
using entry_to_node() to mask off the low tag bit from the pointer.  And
once you do that, you might as well just use the now cleaned-up pointer
directly.

[ Side note: the multi-order code isn't actually ever used in the kernel
  right now, and the only reason I didn't just delete all that code is
  that Kirill Shutemov piped up and said:

    "Well, my ext4-with-huge-pages patchset[1] uses multi-order entries.
     It also converts shmem-with-huge-pages and hugetlb to them.

     I'm okay with converting it to other mechanism, but I need
     something.  (I looked into Konstantin's RFC patchset[2].  It looks
     okay, but I don't feel myself qualified to review it as I don't
     know much about radix-tree internals.)"

  [1] http://lkml.kernel.org/r/20160915115523.29737-1-kirill.shutemov@linux.intel.com
  [2] http://lkml.kernel.org/r/147230727479.9957.1087787722571077339.stgit@zurg ]

Reported-by: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Cedric Blancher <cedric.blancher@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When we replace a multiorder entry, check that all indices reflect the
new value.

Also, compile the test suite with -O2, which shows other problems with
the code due to some dodgy pointer operations in the radix tree code.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

The iter->seq can be reset outside the protection of the mutex. So can
reading of user data. Move the mutex up to the beginning of the function.

Fixes: d7350c3f45694 ("tracing/core: make the read callbacks reentrants")
Cc: stable@vger.kernel.org # 2.6.30+
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>