linux-kernel - [PATCH 1/3] mm/memory.c: Use folios in __copy_remote_vm

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Message-ID: <20250709194017.927978-4-vishal.moola@gmail.com>
Date: Wed,  9 Jul 2025 12:40:16 -0700
From: "Vishal Moola (Oracle)" <vishal.moola@...il.com>
To: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>,
	David Hildenbrand <david@...hat.com>,
	Jordan Rome <linux@...danrome.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Vishal Moola (Oracle)" <vishal.moola@...il.com>
Subject: [PATCH 1/3] mm/memory.c: Use folios in __copy_remote_vm_str()

Use kmap_local_folio() instead of kmap_local_page().
Replaces 2 calls to compound_head() from unmap_and_put_page() with one.

This prepares us for the removal of unmap_and_put_page().

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@...il.com>
---
 mm/memory.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 1174f3001307..d63f0d5abcc9 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -6815,6 +6815,7 @@ static int __copy_remote_vm_str(struct mm_struct *mm, unsigned long addr,
 	while (len) {
 		int bytes, offset, retval;
 		void *maddr;
+		struct folio *folio;
 		struct page *page;
 		struct vm_area_struct *vma = NULL;
 
@@ -6830,17 +6831,18 @@ static int __copy_remote_vm_str(struct mm_struct *mm, unsigned long addr,
 			goto out;
 		}
 
+		folio = page_folio(page);
 		bytes = len;
 		offset = addr & (PAGE_SIZE - 1);
 		if (bytes > PAGE_SIZE - offset)
 			bytes = PAGE_SIZE - offset;
 
-		maddr = kmap_local_page(page);
+		maddr = kmap_local_folio(folio, folio_page_idx(folio, page) * PAGE_SIZE);
 		retval = strscpy(buf, maddr + offset, bytes);
 		if (retval >= 0) {
 			/* Found the end of the string */
 			buf += retval;
-			unmap_and_put_page(page, maddr);
+			folio_release_kmap(folio, maddr);
 			break;
 		}
 
@@ -6858,7 +6860,7 @@ static int __copy_remote_vm_str(struct mm_struct *mm, unsigned long addr,
 		}
 		len -= bytes;
 
-		unmap_and_put_page(page, maddr);
+		folio_release_kmap(folio, maddr);
 	}
 
 out:
-- 
2.50.0