Merge branch 'akpm' (patches from Andrew)

Merge misc fixes from Andrew Morton:
 "15 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm, docs: update memory.stat description with workingset* entries
  mm: vmscan: scan until it finds eligible pages
  mm, thp: copying user pages must schedule on collapse
  dax: fix PMD data corruption when fault races with write
  dax: fix data corruption when fault races with write
  ext4: return to starting transaction in ext4_dax_huge_fault()
  mm: fix data corruption due to stale mmap reads
  dax: prevent invalidation of mapped DAX entries
  Tigran has moved
  mm, vmalloc: fix vmalloc users tracking properly
  mm/khugepaged: add missed tracepoint for collapse_huge_page_swapin
  gcov: support GCC 7.1
  mm, vmstat: Remove spurious WARN() during zoneinfo print
  time: delete current_fs_time()
  hwpoison, memcg: forcibly uncharge LRU pages

1 files changed, 15 insertions, 6 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2f45c0520f43..8ad39bbc79e6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1449,7 +1449,7 @@ static __always_inline void update_lru_sizes(struct lruvec *lruvec,
  *
  * Appropriate locks must be held before calling this function.
  *
- * @nr_to_scan:	The number of pages to look through on the list.
+ * @nr_to_scan:	The number of eligible pages to look through on the list.
  * @lruvec:	The LRU vector to pull pages from.
  * @dst:	The temp list to put pages on to.
  * @nr_scanned:	The number of pages that were scanned.
@@ -1469,11 +1469,13 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 	unsigned long nr_zone_taken[MAX_NR_ZONES] = { 0 };
 	unsigned long nr_skipped[MAX_NR_ZONES] = { 0, };
 	unsigned long skipped = 0;
-	unsigned long scan, nr_pages;
+	unsigned long scan, total_scan, nr_pages;
 	LIST_HEAD(pages_skipped);
 
-	for (scan = 0; scan < nr_to_scan && nr_taken < nr_to_scan &&
-					!list_empty(src); scan++) {
+	scan = 0;
+	for (total_scan = 0;
+	     scan < nr_to_scan && nr_taken < nr_to_scan && !list_empty(src);
+	     total_scan++) {
 		struct page *page;
 
 		page = lru_to_page(src);
@@ -1487,6 +1489,13 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 			continue;
 		}
 
+		/*
+		 * Do not count skipped pages because that makes the function
+		 * return with no isolated pages if the LRU mostly contains
+		 * ineligible pages.  This causes the VM to not reclaim any
+		 * pages, triggering a premature OOM.
+		 */
+		scan++;
 		switch (__isolate_lru_page(page, mode)) {
 		case 0:
 			nr_pages = hpage_nr_pages(page);
@@ -1524,9 +1533,9 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 			skipped += nr_skipped[zid];
 		}
 	}
-	*nr_scanned = scan;
+	*nr_scanned = total_scan;
 	trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan,
-				    scan, skipped, nr_taken, mode, lru);
+				    total_scan, skipped, nr_taken, mode, lru);
 	update_lru_sizes(lruvec, lru, nr_zone_taken);
 	return nr_taken;
 }