[merged] thp-mlock-update-unevictable-lrutxt.patch removed from -mm tree

[merged] thp-mlock-update-unevictable-lrutxt.patch removed from -mm tree

[akpm]

The patch titled
     Subject: thp, mlock: update unevictable-lru.txt
has been removed from the -mm tree.  Its filename was
     thp-mlock-update-unevictable-lrutxt.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: thp, mlock: update unevictable-lru.txt

Add description of THP handling into unevictable-lru.txt.

Link: http://lkml.kernel.org/r/1466021202-61880-7-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 Documentation/vm/unevictable-lru.txt |   21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff -puN Documentation/vm/unevictable-lru.txt~thp-mlock-update-unevictable-lrutxt Documentation/vm/unevictable-lru.txt
--- a/Documentation/vm/unevictable-lru.txt~thp-mlock-update-unevictable-lrutxt
+++ a/Documentation/vm/unevictable-lru.txt
@@ -461,6 +461,27 @@ unevictable LRU is enabled, the work of
 the page migration code and the same work flow as described in MIGRATING
 MLOCKED PAGES will apply.
 
+MLOCKING TRANSPARENT HUGE PAGES
+-------------------------------
+
+A transparent huge page is represented by a single entry on an LRU list.
+Therefore, we can only make unevictable an entire compound page, not
+individual subpages.
+
+If a user tries to mlock() part of a huge page, we want the rest of the
+page to be reclaimable.
+
+We cannot just split the page on partial mlock() as split_huge_page() can
+fail and new intermittent failure mode for the syscall is undesirable.
+
+We handle this by keeping PTE-mapped huge pages on normal LRU lists: the
+PMD on border of VM_LOCKED VMA will be split into PTE table.
+
+This way the huge page is accessible for vmscan. Under memory pressure the
+page will be split, subpages which belong to VM_LOCKED VMAs will be moved
+to unevictable LRU and the rest can be reclaimed.
+
+See also comment in follow_trans_huge_pmd().
 
 mmap(MAP_LOCKED) SYSTEM CALL HANDLING
 -------------------------------------
_

Patches currently in -mm which might be from kirill.shutemov@linux.intel.com are