Merge branch 'akpm' (patches from Andrew)

Merge more fixes from Andrew Morton:
 "17 fixes"

Mostly mm fixes and one ocfs2 locking fix.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm: memcontrol: fix network errors from failing __GFP_ATOMIC charges
  mm/memory_hotplug: fix updating the node span
  scripts/gdb: fix debugging modules compiled with hot/cold partitioning
  mm: slab: make page_cgroup_ino() to recognize non-compound slab pages properly
  MAINTAINERS: update information for "MEMORY MANAGEMENT"
  dump_stack: avoid the livelock of the dump_lock
  zswap: add Vitaly to the maintainers list
  mm/page_alloc.c: ratelimit allocation failure warnings more aggressively
  mm/khugepaged: fix might_sleep() warn with CONFIG_HIGHPTE=y
  mm, vmstat: reduce zone->lock holding time by /proc/pagetypeinfo
  mm, vmstat: hide /proc/pagetypeinfo from normal users
  mm/mmu_notifiers: use the right return code for WARN_ON
  ocfs2: protect extent tree in ocfs2_prepare_inode_for_write()
  mm: thp: handle page cache THP correctly in PageTransCompoundMap
  mm, meminit: recalculate pcpu batch and high limits after init completes
  mm/gup_benchmark: fix MAP_HUGETLB case
  mm: memcontrol: fix NULL-ptr deref in percpu stats flush

3 files changed, 23 insertions, 7 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index cc292273e6ba..a2adf95b3f9c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -695,11 +695,6 @@ static inline void *kvcalloc(size_t n, size_t size, gfp_t flags)
 
 extern void kvfree(const void *addr);
 
-static inline atomic_t *compound_mapcount_ptr(struct page *page)
-{
-	return &page[1].compound_mapcount;
-}
-
 static inline int compound_mapcount(struct page *page)
 {
 	VM_BUG_ON_PAGE(!PageCompound(page), page);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 2222fa795284..270aa8fd2800 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -221,6 +221,11 @@ struct page {
 #endif
 } _struct_page_alignment;
 
+static inline atomic_t *compound_mapcount_ptr(struct page *page)
+{
+	return &page[1].compound_mapcount;
+}
+
 /*
  * Used for sizing the vmemmap region on some architectures
  */
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index f91cb8898ff0..1bf83c8fcaa7 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -622,12 +622,28 @@ static inline int PageTransCompound(struct page *page)
  *
  * Unlike PageTransCompound, this is safe to be called only while
  * split_huge_pmd() cannot run from under us, like if protected by the
- * MMU notifier, otherwise it may result in page->_mapcount < 0 false
+ * MMU notifier, otherwise it may result in page->_mapcount check false
  * positives.
+ *
+ * We have to treat page cache THP differently since every subpage of it
+ * would get _mapcount inc'ed once it is PMD mapped.  But, it may be PTE
+ * mapped in the current process so comparing subpage's _mapcount to
+ * compound_mapcount to filter out PTE mapped case.
  */
 static inline int PageTransCompoundMap(struct page *page)
 {
-	return PageTransCompound(page) && atomic_read(&page->_mapcount) < 0;
+	struct page *head;
+
+	if (!PageTransCompound(page))
+		return 0;
+
+	if (PageAnon(page))
+		return atomic_read(&page->_mapcount) < 0;
+
+	head = compound_head(page);
+	/* File THP is PMD mapped and not PTE mapped */
+	return atomic_read(&page->_mapcount) ==
+	       atomic_read(compound_mapcount_ptr(head));
 }
 
 /*