Merge branch 'akpm' (patches from Andrew)

Merge misc fixes from Andrew Morton:
 "14 patches.

  Subsystems affected by this patch series: mm (hugetlb, kasan, gup,
  selftests, z3fold, kfence, memblock, and highmem), squashfs, ia64,
  gcov, and mailmap"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mailmap: update Andrey Konovalov's email address
  mm/highmem: fix CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP
  mm: memblock: fix section mismatch warning again
  kfence: make compatible with kmemleak
  gcov: fix clang-11+ support
  ia64: fix format strings for err_inject
  ia64: mca: allocate early mca with GFP_ATOMIC
  squashfs: fix xattr id and id lookup sanity checks
  squashfs: fix inode lookup sanity checks
  z3fold: prevent reclaim/free race for headless pages
  selftests/vm: fix out-of-tree build
  mm/mmu_notifiers: ensure range_end() is paired with range_start()
  kasan: fix per-page tags for non-page_alloc pages
  hugetlb_cgroup: fix imbalanced css_get and css_put pair for shared mappings

1 files changed, 15 insertions, 1 deletions

diff --git a/mm/z3fold.c b/mm/z3fold.c
index b5dafa7e44e4..9d889ad2bb86 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -1346,8 +1346,22 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
 			page = list_entry(pos, struct page, lru);
 
 			zhdr = page_address(page);
-			if (test_bit(PAGE_HEADLESS, &page->private))
+			if (test_bit(PAGE_HEADLESS, &page->private)) {
+				/*
+				 * For non-headless pages, we wait to do this
+				 * until we have the page lock to avoid racing
+				 * with __z3fold_alloc(). Headless pages don't
+				 * have a lock (and __z3fold_alloc() will never
+				 * see them), but we still need to test and set
+				 * PAGE_CLAIMED to avoid racing with
+				 * z3fold_free(), so just do it now before
+				 * leaving the loop.
+				 */
+				if (test_and_set_bit(PAGE_CLAIMED, &page->private))
+					continue;
+
 				break;
+			}
 
 			if (kref_get_unless_zero(&zhdr->refcount) == 0) {
 				zhdr = NULL;