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authorLinus Torvalds <torvalds@linux-foundation.org>2016-05-19 20:00:06 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-19 20:00:06 -0700
commita05a70db34ba24ca009e1c9cedaef26fd17d5470 (patch)
treed5d8d0c80293bed52f2103ccc56a9e09117dc983 /Documentation/vm
parent03b979dd0323ace8e29a0561cd5232f73a060c09 (diff)
parent4741526b83c5d3a3d661d1896f9e7414c5730bcb (diff)
Merge branch 'akpm' (patches from Andrew)
Merge updates from Andrew Morton: - fsnotify fix - poll() timeout fix - a few scripts/ tweaks - debugobjects updates - the (small) ocfs2 queue - Minor fixes to kernel/padata.c - Maybe half of the MM queue * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (117 commits) mm, page_alloc: restore the original nodemask if the fast path allocation failed mm, page_alloc: uninline the bad page part of check_new_page() mm, page_alloc: don't duplicate code in free_pcp_prepare mm, page_alloc: defer debugging checks of pages allocated from the PCP mm, page_alloc: defer debugging checks of freed pages until a PCP drain cpuset: use static key better and convert to new API mm, page_alloc: inline pageblock lookup in page free fast paths mm, page_alloc: remove unnecessary variable from free_pcppages_bulk mm, page_alloc: pull out side effects from free_pages_check mm, page_alloc: un-inline the bad part of free_pages_check mm, page_alloc: check multiple page fields with a single branch mm, page_alloc: remove field from alloc_context mm, page_alloc: avoid looking up the first zone in a zonelist twice mm, page_alloc: shortcut watermark checks for order-0 pages mm, page_alloc: reduce cost of fair zone allocation policy retry mm, page_alloc: shorten the page allocator fast path mm, page_alloc: check once if a zone has isolated pageblocks mm, page_alloc: move __GFP_HARDWALL modifications out of the fastpath mm, page_alloc: simplify last cpupid reset mm, page_alloc: remove unnecessary initialisation from __alloc_pages_nodemask() ...
Diffstat (limited to 'Documentation/vm')
-rw-r--r--Documentation/vm/transhuge.txt10
1 files changed, 5 insertions, 5 deletions
diff --git a/Documentation/vm/transhuge.txt b/Documentation/vm/transhuge.txt
index d9cb65cf5cfd..fb0e1f2a19cc 100644
--- a/Documentation/vm/transhuge.txt
+++ b/Documentation/vm/transhuge.txt
@@ -394,9 +394,9 @@ hugepage natively. Once finished you can drop the page table lock.
Refcounting on THP is mostly consistent with refcounting on other compound
pages:
- - get_page()/put_page() and GUP operate in head page's ->_count.
+ - get_page()/put_page() and GUP operate in head page's ->_refcount.
- - ->_count in tail pages is always zero: get_page_unless_zero() never
+ - ->_refcount in tail pages is always zero: get_page_unless_zero() never
succeed on tail pages.
- map/unmap of the pages with PTE entry increment/decrement ->_mapcount
@@ -426,15 +426,15 @@ requests to split pinned huge page: it expects page count to be equal to
sum of mapcount of all sub-pages plus one (split_huge_page caller must
have reference for head page).
-split_huge_page uses migration entries to stabilize page->_count and
+split_huge_page uses migration entries to stabilize page->_refcount and
page->_mapcount.
We safe against physical memory scanners too: the only legitimate way
scanner can get reference to a page is get_page_unless_zero().
-All tail pages has zero ->_count until atomic_add(). It prevent scanner
+All tail pages has zero ->_refcount until atomic_add(). It prevent scanner
from geting reference to tail page up to the point. After the atomic_add()
-we don't care about ->_count value. We already known how many references
+we don't care about ->_refcount value. We already known how many references
with should uncharge from head page.
For head page get_page_unless_zero() will succeed and we don't mind. It's