[merged mm-stable] vmcore-convert-mmap_vmcore_fault-to-use-folios.patch removed from -mm tree

[merged mm-stable] vmcore-convert-mmap_vmcore_fault-to-use-folios.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: vmcore: convert mmap_vmcore_fault() to use folios
has been removed from the -mm tree.  Its filename was
     vmcore-convert-mmap_vmcore_fault-to-use-folios.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Tal Zussman <tz2294@columbia.edu>
Subject: vmcore: convert mmap_vmcore_fault() to use folios
Date: Tue, 15 Sep 2026 19:42:15 -0400

Use a folio for the page cache page the s390 fault handler reads the old
kernel's memory into.  This removes four compound_head() calls and one of
the last callers of find_or_create_page().

The vmcore mapping only has order-0 folios, so the logic is unchanged.

Compile tested for s390.

Link: https://lore.kernel.org/20260915-vmcore-fault-folio-v1-1-a0cb6278670f@columbia.edu
Signed-off-by: Tal Zussman <tz2294@columbia.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Dave Young <ruirui.yang@linux.dev>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
---

 fs/proc/vmcore.c |   27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

--- a/fs/proc/vmcore.c~vmcore-convert-mmap_vmcore_fault-to-use-folios
+++ a/fs/proc/vmcore.c
@@ -474,29 +474,30 @@ static vm_fault_t mmap_vmcore_fault(stru
 	pgoff_t index = vmf->pgoff;
 	struct iov_iter iter;
 	struct kvec kvec;
-	struct page *page;
+	struct folio *folio;
 	loff_t offset;
 	int rc;
 
-	page = find_or_create_page(mapping, index, GFP_KERNEL);
-	if (!page)
+	folio = __filemap_get_folio(mapping, index,
+			FGP_LOCK | FGP_ACCESSED | FGP_CREAT, GFP_KERNEL);
+	if (IS_ERR(folio))
 		return VM_FAULT_OOM;
-	if (!PageUptodate(page)) {
-		offset = (loff_t) index << PAGE_SHIFT;
-		kvec.iov_base = page_address(page);
-		kvec.iov_len = PAGE_SIZE;
-		iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, PAGE_SIZE);
+	if (!folio_test_uptodate(folio)) {
+		offset = folio_pos(folio);
+		kvec.iov_base = folio_address(folio);
+		kvec.iov_len = folio_size(folio);
+		iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, folio_size(folio));
 
 		rc = __read_vmcore(&iter, &offset);
 		if (rc < 0) {
-			unlock_page(page);
-			put_page(page);
+			folio_unlock(folio);
+			folio_put(folio);
 			return vmf_error(rc);
 		}
-		SetPageUptodate(page);
+		folio_mark_uptodate(folio);
 	}
-	unlock_page(page);
-	vmf->page = page;
+	folio_unlock(folio);
+	vmf->page = folio_file_page(folio, index);
 	return 0;
 #else
 	return VM_FAULT_SIGBUS;
_

Patches currently in -mm which might be from tz2294@columbia.edu are