+ selftests-mm-khugepaged-initialize-file-contents-via-mmap.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: selftests/mm: khugepaged: initialize file contents via mmap
has been added to the -mm mm-new branch.  Its filename is
     selftests-mm-khugepaged-initialize-file-contents-via-mmap.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-mm-khugepaged-initialize-file-contents-via-mmap.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: Vineet Agarwal <agarwal.vineet2006@gmail.com>
Subject: selftests/mm: khugepaged: initialize file contents via mmap
Date: Wed, 29 Apr 2026 17:28:16 +0530

file_setup_area() currently allocates anonymous memory, fills it, and
writes it into the backing file used for collapse testing.

Instead of copying data through write(), resize the file with ftruncate(),
map it directly with MAP_SHARED, and initialize the mapped area in place.

This simplifies the setup path and avoids the need for explicit partial
write handling.

Link: https://lore.kernel.org/20260429115816.98824-1-agarwal.vineet2006@gmail.com
Signed-off-by: Vineet Agarwal <agarwal.vineet2006@gmail.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Tested-by: Zi Yan <ziy@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 tools/testing/selftests/mm/khugepaged.c |   18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

--- a/tools/testing/selftests/mm/khugepaged.c~selftests-mm-khugepaged-initialize-file-contents-via-mmap
+++ a/tools/testing/selftests/mm/khugepaged.c
@@ -373,7 +373,7 @@ static void *file_setup_area(int nr_hpag
 	unlink(finfo.path);  /* Cleanup from previous failed tests */
 	printf("Creating %s for collapse%s...", finfo.path,
 	       finfo.type == VMA_SHMEM ? " (tmpfs)" : "");
-	fd = open(finfo.path, O_DSYNC | O_CREAT | O_RDWR | O_TRUNC | O_EXCL,
+	fd = open(finfo.path, O_CREAT | O_RDWR | O_TRUNC | O_EXCL,
 		  777);
 	if (fd < 0) {
 		perror("open()");
@@ -381,9 +381,21 @@ static void *file_setup_area(int nr_hpag
 	}
 
 	size = nr_hpages * hpage_pmd_size;
-	p = alloc_mapping(nr_hpages);
+	if (ftruncate(fd, size)) {
+		perror("ftruncate()");
+		exit(EXIT_FAILURE);
+	}
+	p = mmap(BASE_ADDR, size, PROT_READ | PROT_WRITE,
+		MAP_SHARED, fd, 0);
+	if (p != BASE_ADDR) {
+		perror("mmap()");
+		exit(EXIT_FAILURE);
+	}
 	fill_memory(p, 0, size);
-	write(fd, p, size);
+	if (msync(p, size, MS_SYNC)) {
+		perror("msync()");
+		exit(EXIT_FAILURE);
+	}
 	close(fd);
 	munmap(p, size);
 	success("OK");
_

Patches currently in -mm which might be from agarwal.vineet2006@gmail.com are

selftests-mm-khugepaged-initialize-file-contents-via-mmap.patch