+ selftests-mm-fix-read_file-return-value-check.patch added to mm-new branch

The patch titled
     Subject: selftests/mm: fix read_file() return value check
has been added to the -mm mm-new branch.  Its filename is
     selftests-mm-fix-read_file-return-value-check.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-mm-fix-read_file-return-value-check.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: Hongfu Li <[email protected]>
Subject: selftests/mm: fix read_file() return value check
Date: Fri, 7 Aug 2026 09:35:55 +0800

read_file() returns 0 on open/read failures and never returns negative
values.  Existing < 0 error checks never trigger, so read failures are
silently ignored.  Check for zero return to detect read_file() failures.

Also fix misleading error message in get_finfo().  The error string
incorrectly references read_num when reading uevent files.

Link: https://lore.kernel.org/[email protected]
Fixes: e0c13f9761df ("khugepaged: add self test")
Signed-off-by: Hongfu Li <[email protected]>
Acked-by: David Hildenbrand (Arm) <[email protected]>
Cc: Baolin Wang <[email protected]>
Cc: Barry Song <[email protected]>
Cc: Dev Jain <[email protected]>
Cc: Lance Yang <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 tools/testing/selftests/mm/khugepaged.c |    4 ++--
 tools/testing/selftests/mm/vm_util.c    |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

--- a/tools/testing/selftests/mm/khugepaged.c~selftests-mm-fix-read_file-return-value-check
+++ a/tools/testing/selftests/mm/khugepaged.c
@@ -163,8 +163,8 @@ static void get_finfo(const char *dir)
 		     major(path_stat.st_dev), minor(path_stat.st_dev))
 	    >= sizeof(path))
 		ksft_exit_fail_msg("%s: Pathname is too long\n", __func__);
-	if (read_file(path, buf, sizeof(buf)) < 0)
-		ksft_exit_fail_perror("read_file(read_num)");
+	if (!read_file(path, buf, sizeof(buf)))
+		ksft_exit_fail_perror("read_file(uevent)");
 	if (strstr(buf, "DEVTYPE=disk")) {
 		/* Found it */
 		if (snprintf(finfo.dev_queue_read_ahead_path,
--- a/tools/testing/selftests/mm/vm_util.c~selftests-mm-fix-read_file-return-value-check
+++ a/tools/testing/selftests/mm/vm_util.c
@@ -946,7 +946,7 @@ unsigned long read_num(const char *path)
 {
 	char buf[21];
 
-	if (read_file(path, buf, sizeof(buf)) < 0)
+	if (!read_file(path, buf, sizeof(buf)))
 		ksft_exit_fail_perror("read_file()");
 
 	return strtoul(buf, NULL, 10);
_

Patches currently in -mm which might be from [email protected] are

mm-swap-fix-swap_cluster_lock-config_swap-stub-signature-mismatch.patch
ksm-update-comments-and-docs-to-reference-folio-mapping.patch
mm-use-a-folio-in-the-softleaf_is_device_private-path.patch
selftests-mm-drop-duplicate-test_seal_mprotect_two_vma_with_gap-call.patch
selftests-mm-fix-read_file-return-value-check.patch
selftests-prctl-fix-non-anonymous-vma-mapping-in-set-anon-vma-name-test.patch