[v2,1/5] lib/test_hmm: make dmirror_atomic_map() consume a single page

Commit Message

David Hildenbrand Feb. 26, 2025, 1:22 p.m. UTC

The caller now always passes a single page; let's simplify, and return
"0" on success.

Reviewed-by: Alistair Popple <[e-mail]>
Signed-off-by: David Hildenbrand <[e-mail]>
---
 lib/test_hmm.c | 32 ++++++++++----------------------
 1 file changed, 10 insertions(+), 22 deletions(-)

Patch

diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 155b18cd9f2af..5b144bc5c4ec7 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -707,34 +707,23 @@  static int dmirror_check_atomic(struct dmirror *dmirror, unsigned long start,
 	return 0;
 }
 
-static int dmirror_atomic_map(unsigned long start, unsigned long end,
-			      struct page **pages, struct dmirror *dmirror)
+static int dmirror_atomic_map(unsigned long addr, struct page *page,
+		struct dmirror *dmirror)
 {
-	unsigned long pfn, mapped = 0;
-	int i;
+	void *entry;
 
 	/* Map the migrated pages into the device's page tables. */
 	mutex_lock(&dmirror->mutex);
 
-	for (i = 0, pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++, i++) {
-		void *entry;
-
-		if (!pages[i])
-			continue;
-
-		entry = pages[i];
-		entry = xa_tag_pointer(entry, DPT_XA_TAG_ATOMIC);
-		entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
-		if (xa_is_err(entry)) {
-			mutex_unlock(&dmirror->mutex);
-			return xa_err(entry);
-		}
-
-		mapped++;
+	entry = xa_tag_pointer(page, DPT_XA_TAG_ATOMIC);
+	entry = xa_store(&dmirror->pt, addr >> PAGE_SHIFT, entry, GFP_ATOMIC);
+	if (xa_is_err(entry)) {
+		mutex_unlock(&dmirror->mutex);
+		return xa_err(entry);
 	}
 
 	mutex_unlock(&dmirror->mutex);
-	return mapped;
+	return 0;
 }
 
 static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
@@ -804,8 +793,7 @@  static int dmirror_exclusive(struct dmirror *dmirror,
 			break;
 		}
 
-		ret = dmirror_atomic_map(addr, addr + PAGE_SIZE, &page, dmirror);
-		ret = ret == 1 ? 0 : -EBUSY;
+		ret = dmirror_atomic_map(addr, page, dmirror);
 		folio_unlock(folio);
 		folio_put(folio);
 	}