Merge branch 'akpm' (patches from Andrew)

Merge second set of updates from Andrew Morton:
 "More of MM"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (83 commits)
  mm/nommu.c: fix arithmetic overflow in __vm_enough_memory()
  mm/mmap.c: fix arithmetic overflow in __vm_enough_memory()
  vmstat: Reduce time interval to stat update on idle cpu
  mm/page_owner.c: remove unnecessary stack_trace field
  Documentation/filesystems/proc.txt: describe /proc/<pid>/map_files
  mm: incorporate read-only pages into transparent huge pages
  vmstat: do not use deferrable delayed work for vmstat_update
  mm: more aggressive page stealing for UNMOVABLE allocations
  mm: always steal split buddies in fallback allocations
  mm: when stealing freepages, also take pages created by splitting buddy page
  mincore: apply page table walker on do_mincore()
  mm: /proc/pid/clear_refs: avoid split_huge_page()
  mm: pagewalk: fix misbehavior of walk_page_range for vma(VM_PFNMAP)
  mempolicy: apply page table walker on queue_pages_range()
  arch/powerpc/mm/subpage-prot.c: use walk->vma and walk_page_vma()
  memcg: cleanup preparation for page table walk
  numa_maps: remove numa_maps->vma
  numa_maps: fix typo in gather_hugetbl_stats
  pagemap: use walk->vma instead of calling find_vma()
  clear_refs: remove clear_refs_private->vma and introduce clear_refs_test_walk()
  ...

1 files changed, 23 insertions, 0 deletions

diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 79b3cc821e7b..cf8fc2f0b34b 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -42,6 +42,7 @@ Table of Contents
   3.6   /proc/<pid>/comm  & /proc/<pid>/task/<tid>/comm
   3.7   /proc/<pid>/task/<tid>/children - Information about task children
   3.8   /proc/<pid>/fdinfo/<fd> - Information about opened file
+  3.9   /proc/<pid>/map_files - Information about memory mapped files
 
   4     Configuring procfs
   4.1   Mount options
@@ -1763,6 +1764,28 @@ pair provide additional information particular to the objects they represent.
         with TIMER_ABSTIME option which will be shown in 'settime flags', but 'it_value'
         still exhibits timer's remaining time.
 
+3.9     /proc/<pid>/map_files - Information about memory mapped files
+---------------------------------------------------------------------
+This directory contains symbolic links which represent memory mapped files
+the process is maintaining.  Example output:
+
+     | lr-------- 1 root root 64 Jan 27 11:24 333c600000-333c620000 -> /usr/lib64/ld-2.18.so
+     | lr-------- 1 root root 64 Jan 27 11:24 333c81f000-333c820000 -> /usr/lib64/ld-2.18.so
+     | lr-------- 1 root root 64 Jan 27 11:24 333c820000-333c821000 -> /usr/lib64/ld-2.18.so
+     | ...
+     | lr-------- 1 root root 64 Jan 27 11:24 35d0421000-35d0422000 -> /usr/lib64/libselinux.so.1
+     | lr-------- 1 root root 64 Jan 27 11:24 400000-41a000 -> /usr/bin/ls
+
+The name of a link represents the virtual memory bounds of a mapping, i.e.
+vm_area_struct::vm_start-vm_area_struct::vm_end.
+
+The main purpose of the map_files is to retrieve a set of memory mapped
+files in a fast way instead of parsing /proc/<pid>/maps or
+/proc/<pid>/smaps, both of which contain many more records.  At the same
+time one can open(2) mappings from the listings of two processes and
+comparing their inode numbers to figure out which anonymous memory areas
+are actually shared.
+
 ------------------------------------------------------------------------------
 Configuring procfs
 ------------------------------------------------------------------------------