+ selftests-mm-handle-einval-when-configuring-gigantic-hugepages.patch added to mm-new branch

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

The patch titled
     Subject: selftests/mm: handle EINVAL when configuring gigantic hugepages
has been added to the -mm mm-new branch.  Its filename is
     selftests-mm-handle-einval-when-configuring-gigantic-hugepages.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-mm-handle-einval-when-configuring-gigantic-hugepages.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: Sayali Patil <sayalip@linux.ibm.com>
Subject: selftests/mm: handle EINVAL when configuring gigantic hugepages
Date: Thu, 25 Jun 2026 18:10:16 +0530

Patch series "selftests/mm: avoid false failures in hugetlb and KSM tests".

This series fixes issues in the hugetlb and KSM MM selftest categories
that can report failures when the prerequisites for the tests are not
satisfied.

Patch 1 updates the hugetlb selftest helpers to handle -EINVAL when
attempting to configure gigantic HugeTLB pages via nr_hugepages.  PowerPC
hash MMU pSeries systems expose gigantic hugepage sizes but do not allow
runtime allocation of such pages, causing the sysfs write to fail.  Handle
this case gracefully and continue running the test instead of aborting.

Patch 2 fixes the KSM NUMA merge test on systems with memoryless NUMA
nodes.  The test currently relies on the number of configured NUMA nodes
and may attempt allocations on nodes that have no memory, resulting in
spurious failures.  Count only NUMA nodes that contain memory and skip the
test when fewer than two such nodes are available.

These changes improve handling of unsupported test configurations and
unmet test prerequisites, avoiding spurious failures.


This patch (of 2):

Some MM selftests attempt to configure the amount of HugeTLB pages of
different sizes by writing to nr_hugepages.

PowerPC hash MMU pSeries systems advertise gigantic hugepage sizes but do
not support runtime allocation of such pages, writes to the corresponding
nr_hugepages file fail with -EINVAL.  This causes the test to bail out
even though the failure is due to a platform limitation rather than the
functionality being tested.

Treat -EINVAL from the sysfs write as a skipped configuration request and
continue running the test instead of failing.

Before patch:
   -------------------------
   running ./hugetlb-madvise
   -------------------------
   TAP version 13
   1..1
     [INFO] detected hugetlb page size: 16777216 KiB
     [INFO] detected hugetlb page size: 16384 KiB
    ok 1 MADV_DONTNEED and MADV_REMOVE on hugetlb
    Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
    Bail out! /sys/kernel/mm/hugepages/hugepages-16777216kB/nr_hugepages
    write(0) failed: Invalid argument
    Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0
    [FAIL]

After patch:
   -------------------------
   running ./hugetlb-madvise
   -------------------------
   TAP version 13
   1..1
    [INFO] detected hugetlb page size: 16777216 KiB
    [INFO] detected hugetlb page size: 16384 KiB
   ok 1 MADV_DONTNEED and MADV_REMOVE on hugetlb
   Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
   /sys/kernel/mm/hugepages/hugepages-16777216kB/nr_hugepages
   write(0) failed: Invalid argument
   [PASS]

Link: https://lore.kernel.org/cover.1782365671.git.sayalip@linux.ibm.com
Link: https://lore.kernel.org/8bfa921e30eb94072685103f6496784aa23bb166.1782365671.git.sayalip@linux.ibm.com
Fixes: 9d07250ea1eb ("selftests/mm: hugepage_settings: add APIs to get and set nr_hugepages")
Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 tools/testing/selftests/mm/vm_util.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/tools/testing/selftests/mm/vm_util.c~selftests-mm-handle-einval-when-configuring-gigantic-hugepages
+++ a/tools/testing/selftests/mm/vm_util.c
@@ -735,6 +735,13 @@ void write_file(const char *path, const
 	saved_errno = errno;
 	close(fd);
 	errno = saved_errno;
+
+	if (numwritten < 0 && errno == EINVAL) {
+		ksft_print_msg("%s write(%.*s) failed: %s\n", path,
+			       (int)(buflen - 1), buf, strerror(errno));
+		return;
+	}
+
 	if (numwritten < 0)
 		ksft_exit_fail_msg("%s write(%.*s) failed: %s\n", path, (int)(buflen - 1),
 				buf, strerror(errno));
_

Patches currently in -mm which might be from sayalip@linux.ibm.com are

selftests-mm-handle-einval-when-configuring-gigantic-hugepages.patch
selftests-mm-fix-ksm-numa-merge-test-for-systems-with-memoryless-numa-nodes.patch