From: Ralph Campbell <rcampbell@xxxxxxxxxx>
Some minor wording changes and typo corrections.
Signed-off-by: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
---
Documentation/vm/hugetlbfs_reserv.rst | 17 +++---
Documentation/vm/transhuge.rst | 77 ++++++++++++++-------------
2 files changed, 48 insertions(+), 46 deletions(-)
diff --git a/Documentation/vm/hugetlbfs_reserv.rst b/Documentation/vm/hugetlbfs_reserv.rst
index 9d200762114f..f143954e0d05 100644
--- a/Documentation/vm/hugetlbfs_reserv.rst
+++ b/Documentation/vm/hugetlbfs_reserv.rst
@@ -85,10 +85,10 @@ Reservation Map Location (Private or Shared)
A huge page mapping or segment is either private or shared. If private,
it is typically only available to a single address space (task). If shared,
it can be mapped into multiple address spaces (tasks). The location and
-semantics of the reservation map is significantly different for two types
+semantics of the reservation map is significantly different for the two types
of mappings. Location differences are:
-- For private mappings, the reservation map hangs off the the VMA structure.
+- For private mappings, the reservation map hangs off the VMA structure.
Specifically, vma->vm_private_data. This reserve map is created at the
time the mapping (mmap(MAP_PRIVATE)) is created.
- For shared mappings, the reservation map hangs off the inode. Specifically,
@@ -109,15 +109,15 @@ These operations result in a call to the routine hugetlb_reserve_pages()::
struct vm_area_struct *vma,
vm_flags_t vm_flags)
-The first thing hugetlb_reserve_pages() does is check for the NORESERVE
+The first thing hugetlb_reserve_pages() does is check if the NORESERVE
flag was specified in either the shmget() or mmap() call. If NORESERVE
-was specified, then this routine returns immediately as no reservation
+was specified, then this routine returns immediately as no reservations
are desired.
The arguments 'from' and 'to' are huge page indices into the mapping or
underlying file. For shmget(), 'from' is always 0 and 'to' corresponds to
the length of the segment/mapping. For mmap(), the offset argument could
-be used to specify the offset into the underlying file. In such a case
+be used to specify the offset into the underlying file. In such a case,
the 'from' and 'to' arguments have been adjusted by this offset.
One of the big differences between PRIVATE and SHARED mappings is the way
@@ -138,7 +138,8 @@ to indicate this VMA owns the reservations.
The reservation map is consulted to determine how many huge page reservations
are needed for the current mapping/segment. For private mappings, this is
-always the value (to - from). However, for shared mappings it is possible that some reservations may already exist within the range (to - from). See the
+always the value (to - from). However, for shared mappings it is possible that
+some reservations may already exist within the range (to - from). See the
section :ref:`Reservation Map Modifications <resv_map_modifications>`
for details on how this is accomplished.
@@ -165,7 +166,7 @@ these counters.
If there were enough free huge pages and the global count resv_huge_pages
was adjusted, then the reservation map associated with the mapping is
modified to reflect the reservations. In the case of a shared mapping, a
-file_region will exist that includes the range 'from' 'to'. For private
+file_region will exist that includes the range 'from' - 'to'. For private
mappings, no modifications are made to the reservation map as lack of an
entry indicates a reservation exists.
@@ -239,7 +240,7 @@ subpool accounting when the page is freed.
The routine vma_commit_reservation() is then called to adjust the reserve
map based on the consumption of the reservation. In general, this involves
ensuring the page is represented within a file_region structure of the region
-map. For shared mappings where the the reservation was present, an entry
+map. For shared mappings where the reservation was present, an entry
in the reserve map already existed so no change is made. However, if there
was no reservation in a shared mapping or this was a private mapping a new
entry must be created.
diff --git a/Documentation/vm/transhuge.rst b/Documentation/vm/transhuge.rst
index a8cf6809e36e..0be61b0d75d3 100644
--- a/Documentation/vm/transhuge.rst
+++ b/Documentation/vm/transhuge.rst
@@ -4,8 +4,9 @@
Transparent Hugepage Support
============================
-This document describes design principles Transparent Hugepage (THP)
-Support and its interaction with other parts of the memory management.
+This document describes design principles for Transparent Hugepage (THP)
+support and its interaction with other parts of the memory management
+system.
Design principles
=================
@@ -35,27 +36,27 @@ Design principles
get_user_pages and follow_page
==============================
-get_user_pages and follow_page if run on a hugepage, will return the
+get_user_pages and follow_page, if run on a hugepage, will return the
head or tail pages as usual (exactly as they would do on
-hugetlbfs). Most gup users will only care about the actual physical
+hugetlbfs). Most GUP users will only care about the actual physical
address of the page and its temporary pinning to release after the I/O
is complete, so they won't ever notice the fact the page is huge. But
if any driver is going to mangle over the page structure of the tail
page (like for checking page->mapping or other bits that are relevant
for the head page and not the tail page), it should be updated to jump
-to check head page instead. Taking reference on any head/tail page would
-prevent page from being split by anyone.
+to check head page instead. Taking a reference on any head/tail page would
+prevent the page from being split by anyone.
.. note::
these aren't new constraints to the GUP API, and they match the
- same constrains that applies to hugetlbfs too, so any driver capable
+ same constraints that apply to hugetlbfs too, so any driver capable
of handling GUP on hugetlbfs will also work fine on transparent
hugepage backed mappings.
In case you can't handle compound pages if they're returned by
-follow_page, the FOLL_SPLIT bit can be specified as parameter to
+follow_page, the FOLL_SPLIT bit can be specified as a parameter to
follow_page, so that it will split the hugepages before returning
-them. Migration for example passes FOLL_SPLIT as parameter to
+them. Migration for example passes FOLL_SPLIT as a parameter to
