linux-kernel - [PATCH v1 1/4] lib/test_hmm: make dmirror_atomic

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Message-ID: <20250129115803.2084769-2-david@redhat.com>
Date: Wed, 29 Jan 2025 12:57:59 +0100
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-doc@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	linux-mm@...ck.org,
	nouveau@...ts.freedesktop.org,
	David Hildenbrand <david@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jérôme Glisse <jglisse@...hat.com>,
	Jonathan Corbet <corbet@....net>,
	Alex Shi <alexs@...nel.org>,
	Yanteng Si <si.yanteng@...ux.dev>,
	Karol Herbst <kherbst@...hat.com>,
	Lyude Paul <lyude@...hat.com>,
	Danilo Krummrich <dakr@...nel.org>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Jann Horn <jannh@...gle.com>,
	Pasha Tatashin <pasha.tatashin@...een.com>,
	Peter Xu <peterx@...hat.com>,
	Alistair Popple <apopple@...dia.com>,
	Jason Gunthorpe <jgg@...dia.com>
Subject: [PATCH v1 1/4] lib/test_hmm: make dmirror_atomic_map() consume a single page

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

Signed-off-by: David Hildenbrand <david@...hat.com>
---
 lib/test_hmm.c | 33 ++++++++++-----------------------
 1 file changed, 10 insertions(+), 23 deletions(-)

diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 9e1b07a227a3..1c0a58279db9 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -706,34 +706,23 @@ 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,
@@ -803,9 +792,7 @@ static int dmirror_exclusive(struct dmirror *dmirror,
 			break;
 		}
 
-		ret = dmirror_atomic_map(addr, addr + PAGE_SIZE, &page, dmirror);
-		if (!ret)
-			ret = -EBUSY;
+		ret = dmirror_atomic_map(addr, page, dmirror);
 		folio_unlock(folio);
 		folio_put(folio);
 
-- 
2.48.1