@@ -1464,11 +1464,19 @@ void end_page_writeback(struct page *pag
rotate_reclaimable_page(page);
}
+ /*
+ * Writeback does not hold a page reference of its own, relying
+ * on truncation to wait for the clearing of PG_writeback.
+ * But here we must make sure that the page is not freed and
+ * reused before the wake_up_page().
+ */
+ get_page(page);
if (!test_clear_page_writeback(page))
BUG();
smp_mb__after_atomic();
wake_up_page(page, PG_writeback);
+ put_page(page);
}
EXPORT_SYMBOL(end_page_writeback);
@@ -2754,12 +2754,6 @@ int test_clear_page_writeback(struct pag
} else {
ret = TestClearPageWriteback(page);
}
- /*
- * NOTE: Page might be free now! Writeback doesn't hold a page
- * reference on its own, it relies on truncation to wait for
- * the clearing of PG_writeback. The below can only access
- * page state that is static across allocation cycles.
- */
if (ret) {
dec_lruvec_state(lruvec, NR_WRITEBACK);
dec_zone_page_state(page, NR_ZONE_WRITE_PENDING);