1 files changed, 11 insertions, 4 deletions
diff --git a/mm/ksm.c b/mm/ksm.c
index 8be2b144fefd..a9d3e719e089 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1270,8 +1270,15 @@ static int write_protect_page(struct vm_area_struct *vma, struct folio *folio,
 	if (WARN_ONCE(!pvmw.pte, "Unexpected PMD mapping?"))
 		goto out_unlock;
 
-	anon_exclusive = PageAnonExclusive(&folio->page);
 	entry = ptep_get(pvmw.pte);
+	/*
+	 * Handle PFN swap PTEs, such as device-exclusive ones, that actually
+	 * map pages: give up just like the next folio_walk would.
+	 */
+	if (unlikely(!pte_present(entry)))
+		goto out_unlock;
+
+	anon_exclusive = PageAnonExclusive(&folio->page);
 	if (pte_write(entry) || pte_dirty(entry) ||
 	    anon_exclusive || mm_tlb_flush_pending(mm)) {
 		swapped = folio_test_swapcache(folio);
@@ -3662,10 +3669,10 @@ static ssize_t advisor_mode_show(struct kobject *kobj,
 {
 	const char *output;
 
-	if (ksm_advisor == KSM_ADVISOR_NONE)
-		output = "[none] scan-time";
-	else if (ksm_advisor == KSM_ADVISOR_SCAN_TIME)
+	if (ksm_advisor == KSM_ADVISOR_SCAN_TIME)
 		output = "none [scan-time]";
+	else
+		output = "[none] scan-time";
 
 	return sysfs_emit(buf, "%s\n", output);
 }