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-rw-r--r--mm/z3fold.c16
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;