Merge branch 'akpm' (incoming from Andrew)

Merge first patch-bomb from Andrew Morton:

 - a couple of misc things

 - inotify/fsnotify work from Jan

 - ocfs2 updates (partial)

 - about half of MM

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (117 commits)
  mm/migrate: remove unused function, fail_migrate_page()
  mm/migrate: remove putback_lru_pages, fix comment on putback_movable_pages
  mm/migrate: correct failure handling if !hugepage_migration_support()
  mm/migrate: add comment about permanent failure path
  mm, page_alloc: warn for non-blockable __GFP_NOFAIL allocation failure
  mm: compaction: reset scanner positions immediately when they meet
  mm: compaction: do not mark unmovable pageblocks as skipped in async compaction
  mm: compaction: detect when scanners meet in isolate_freepages
  mm: compaction: reset cached scanner pfn's before reading them
  mm: compaction: encapsulate defer reset logic
  mm: compaction: trace compaction begin and end
  memcg, oom: lock mem_cgroup_print_oom_info
  sched: add tracepoints related to NUMA task migration
  mm: numa: do not automatically migrate KSM pages
  mm: numa: trace tasks that fail migration due to rate limiting
  mm: numa: limit scope of lock for NUMA migrate rate limiting
  mm: numa: make NUMA-migrate related functions static
  lib/show_mem.c: show num_poisoned_pages when oom
  mm/hwpoison: add '#' to hwpoison_inject
  mm/memblock: use WARN_ONCE when MAX_NUMNODES passed as input parameter
  ...

1 files changed, 23 insertions, 0 deletions

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 91672e2..db51201 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -157,6 +157,26 @@ static inline int hpage_nr_pages(struct page *page)
 		return HPAGE_PMD_NR;
 	return 1;
 }
+/*
+ * compound_trans_head() should be used instead of compound_head(),
+ * whenever the "page" passed as parameter could be the tail of a
+ * transparent hugepage that could be undergoing a
+ * __split_huge_page_refcount(). The page structure layout often
+ * changes across releases and it makes extensive use of unions. So if
+ * the page structure layout will change in a way that
+ * page->first_page gets clobbered by __split_huge_page_refcount, the
+ * implementation making use of smp_rmb() will be required.
+ *
+ * Currently we define compound_trans_head as compound_head, because
+ * page->private is in the same union with page->first_page, and
+ * page->private isn't clobbered. However this also means we're
+ * currently leaving dirt into the page->private field of anonymous
+ * pages resulting from a THP split, instead of setting page->private
+ * to zero like for every other page that has PG_private not set. But
+ * anonymous pages don't use page->private so this is not a problem.
+ */
+#if 0
+/* This will be needed if page->private will be clobbered in split_huge_page */
 static inline struct page *compound_trans_head(struct page *page)
 {
 	if (PageTail(page)) {
@@ -174,6 +194,9 @@ static inline struct page *compound_trans_head(struct page *page)
 	}
 	return page;
 }
+#else
+#define compound_trans_head(page) compound_head(page)
+#endif
 
 extern int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
 				unsigned long addr, pmd_t pmd, pmd_t *pmdp);