From: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Date: Wed, 9 Jul 2025 19:40:16 +0000 (-0700)
Subject: mm/memory.c: use folios in __copy_remote_vm_str()
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0ec5eea20821287d9d9d4ec477f7cd0e15315518;p=thirdparty%2Fkernel%2Flinux.git

mm/memory.c: use folios in __copy_remote_vm_str()

Patch series "Remove unmap_and_put_page()".

This patchset uses folios in both the callers of unmap_and_put_page(),
saving a couple calls to compound_head() wrappers.


This patch (of 3):

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().

Link: https://lkml.kernel.org/r/20250709194017.927978-3-vishal.moola@gmail.com
Link: https://lkml.kernel.org/r/20250709194017.927978-4-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Jordan Rome <linux@jordanrome.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/memory.c b/mm/memory.c
index 4619bf5874af0..cb2f1296854a6 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: