Merge branch 'akpm' (patches from Andrew)

Merge misc fixes from Andrew Morton:
 "14 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm, page_alloc: do not wake kswapd with zone lock held
  hugetlbfs: revert "use i_mmap_rwsem for more pmd sharing synchronization"
  hugetlbfs: revert "Use i_mmap_rwsem to fix page fault/truncate race"
  mm: page_mapped: don't assume compound page is huge or THP
  mm/memory.c: initialise mmu_notifier_range correctly
  tools/vm/page_owner: use page_owner_sort in the use example
  kasan: fix krealloc handling for tag-based mode
  kasan: make tag based mode work with CONFIG_HARDENED_USERCOPY
  kasan, arm64: use ARCH_SLAB_MINALIGN instead of manual aligning
  mm, memcg: fix reclaim deadlock with writeback
  mm/usercopy.c: no check page span for stack objects
  slab: alien caches must not be initialized if the allocation of the alien cache failed
  fork, memcg: fix cached_stacks case
  zram: idle writeback fixes and cleanup

1 files changed, 7 insertions, 1 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cde5dac6229a..d295c9bc01a8 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2214,7 +2214,7 @@ static void steal_suitable_fallback(struct zone *zone, struct page *page,
          */
         boost_watermark(zone);
         if (alloc_flags & ALLOC_KSWAPD)
-                wakeup_kswapd(zone, 0, 0, zone_idx(zone));
+                set_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
 
         /* We are not allowed to try stealing from the whole block */
         if (!whole_block)
@@ -3102,6 +3102,12 @@ struct page *rmqueue(struct zone *preferred_zone,
         local_irq_restore(flags);
 
 out:
+        /* Separate test+clear to avoid unnecessary atomics */
+        if (test_bit(ZONE_BOOSTED_WATERMARK, &zone->flags)) {
+                clear_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
+                wakeup_kswapd(zone, 0, 0, zone_idx(zone));
+        }
+
         VM_BUG_ON_PAGE(page && bad_range(zone, page), page);
         return page;