Merge branch 'akpm' (patches from Andrew)

Merge misc fixes from Andrew Morton:
 "15 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  linux/kernel.h: fix overflow for DIV_ROUND_UP_ULL
  mm, swap: fix THP swap out
  fork,memcg: alloc_thread_stack_node needs to set tsk->stack
  MAINTAINERS: add CLANG/LLVM BUILD SUPPORT info
  mm/vmalloc.c: avoid bogus -Wmaybe-uninitialized warning
  mm/page_idle.c: fix oops because end_pfn is larger than max_pfn
  initramfs: fix populate_initrd_image() section mismatch
  mm/oom_kill.c: fix uninitialized oc->constraint
  mm: hugetlb: soft-offline: dissolve_free_huge_page() return zero on !PageHuge
  mm: soft-offline: return -EBUSY if set_hwpoison_free_buddy_page() fails
  signal: remove the wrong signal_pending() check in restore_user_sigmask()
  fs/binfmt_flat.c: make load_flat_shared_library() work
  mm/mempolicy.c: fix an incorrect rebind node in mpol_rebind_nodemask
  fs/proc/array.c: allow reporting eip/esp for all coredumping threads
  mm/dev_pfn: exclude MEMORY_DEVICE_PRIVATE while computing virtual address

1 files changed, 20 insertions, 9 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ac843d32b019..ede7e7f5d1ab 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1510,16 +1510,29 @@ static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
 
 /*
  * Dissolve a given free hugepage into free buddy pages. This function does
- * nothing for in-use (including surplus) hugepages. Returns -EBUSY if the
- * dissolution fails because a give page is not a free hugepage, or because
- * free hugepages are fully reserved.
+ * nothing for in-use hugepages and non-hugepages.
+ * This function returns values like below:
+ *
+ *  -EBUSY: failed to dissolved free hugepages or the hugepage is in-use
+ *          (allocated or reserved.)
+ *       0: successfully dissolved free hugepages or the page is not a
+ *          hugepage (considered as already dissolved)
  */
 int dissolve_free_huge_page(struct page *page)
 {
 	int rc = -EBUSY;
 
+	/* Not to disrupt normal path by vainly holding hugetlb_lock */
+	if (!PageHuge(page))
+		return 0;
+
 	spin_lock(&hugetlb_lock);
-	if (PageHuge(page) && !page_count(page)) {
+	if (!PageHuge(page)) {
+		rc = 0;
+		goto out;
+	}
+
+	if (!page_count(page)) {
 		struct page *head = compound_head(page);
 		struct hstate *h = page_hstate(head);
 		int nid = page_to_nid(head);
@@ -1564,11 +1577,9 @@ int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
 
 	for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order) {
 		page = pfn_to_page(pfn);
-		if (PageHuge(page) && !page_count(page)) {
-			rc = dissolve_free_huge_page(page);
-			if (rc)
-				break;
-		}
+		rc = dissolve_free_huge_page(page);
+		if (rc)
+			break;
 	}
 
 	return rc;