Re: [PATCH v11 1/6] selftests/mm: make file helpers return errors

[Sarthak Sharma <sarthak.sharma@arm.com>]

On 9/18/26 4:52 PM, Sarthak Sharma wrote:
> Change read_file(), write_file(), read_num(), write_num() and
> write_num_ignore_einval() in vm_util.c to report failures to callers
> instead of exiting from the helper.
> 
> Make read_file() return a negative errno on failure and 0 on success, so
> callers can distinguish a successful read from an I/O error. Also make
> read_num() reject negative and malformed values.
> 
> Keep write_num_ignore_einval() silent for -EINVAL while returning other
> errors to its caller.
> 
> Update callers to print diagnostics and fail wherever required. Modify
> a comment which implies write_num() uses ksft_exit_fail_msg(). Also add
> a helper print_file_access_error() in hugepage_settings.c to print
> TAP-compatible errors without a kselftest dependency. This prepares the
> helpers to be moved to tools/lib/mm without a kselftest dependency.
> 
> Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> Acked-by: David Hildenbrand (Arm) <david@kernel.org>
> Tested-by: Muhammad Usama Anjum <usama.anjum@arm.com>
> Signed-off-by: Sarthak Sharma <sarthak.sharma@arm.com>
> ---
Hi Andrew!

This fixes an MM selftest build failure in patch 1/6: read_num() changed
its interface, but hugetlb_nr_resv_pages() was missed during the caller
conversion. I'm sorry for missing this.

Can you please apply this fixlet after this patch and before the next
one? Sorry for the inconvenience again.


From f7cfae95a1d0554ea03df320d91641979a9ac473 Mon Sep 17 00:00:00 2001
From: Sarthak Sharma <sarthak.sharma@arm.com>
Date: Fri, 18 Sep 2026 17:40:50 +0530
Subject: [PATCH] fixup! selftests/mm: make file helpers return errors

Convert hugetlb_nr_resv_pages(), which was missed when read_num()
changed to return an error and store the parsed value through an output
pointer.

Signed-off-by: Sarthak Sharma <sarthak.sharma@arm.com>
---
 tools/testing/selftests/mm/hugepage_settings.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/hugepage_settings.c
b/tools/testing/selftests/mm/hugepage_settings.c
index 9a63420d0744..6f3abd357385 100644
--- a/tools/testing/selftests/mm/hugepage_settings.c
+++ b/tools/testing/selftests/mm/hugepage_settings.c
@@ -515,10 +515,18 @@ unsigned long hugetlb_free_pages(unsigned long size)
 unsigned long hugetlb_nr_resv_pages(unsigned long size)
 {
 	char path[PATH_MAX];
+	unsigned long nr;
+	int ret;

 	hugetlb_sysfs_path(path, sizeof(path), size, "resv_hugepages");

-	return read_num(path);
+	ret = read_num(path, &nr);
+	if (ret) {
+		print_file_access_error(path, ret);
+		exit(EXIT_FAILURE);
+	}
+
+	return nr;
 }

 static bool __hugetlb_setup(unsigned long size, unsigned long nr)
-- 
2.53.0