+ selftests-mm-thuge-gen-fix-test_shmget-for-page_size-check.patch added to mm-unstable branch

+ selftests-mm-thuge-gen-fix-test_shmget-for-page_size-check.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: selftests/mm: thuge-gen: fix test_shmget() for PAGE_SIZE check
has been added to the -mm mm-unstable branch.  Its filename is
     selftests-mm-thuge-gen-fix-test_shmget-for-page_size-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-thuge-gen-fix-test_shmget-for-page_size-check.patch

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

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------------------------------------------------------
From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
Subject: selftests/mm: thuge-gen: fix test_shmget() for PAGE_SIZE check
Date: Sun, 09 Aug 2026 11:03:35 +0300

Commit 49a4e7186b08 ("selftests/mm: thuge-gen: add setup of HugeTLB
pages") changed thuge-gen test to use common functions for reading hugetlb
attributes from sysfs, but it missed that the original read_free()
function special cased PAGE_SIZE tests.

For PAGE_SIZE tests, failure to read sysfs was ignored and read_free()
returned 0.

This allowed test_shmget() to essentially skip the check of how many huge
pages was consumed when it ran with PAGE_SIZE.

Commit 3199b0c09efa ("selftests/mm: fix read_file() return value check")
fixed the common read_file() to actually return error on failure and this
exposed the issue in test_shmget() that checks the number of free hugetlb
pages even for PAGE_SIZE test, tries to access

/sys/kernel/mm/hugepages/hugepages-<PAGE_SIZE>/free_hugepages

and obviously fails there.

Gate the checks for free huge pages on size != getpagesize() and
initialize before and after variables to values matching PAGE_SIZE test.

Link: https://lore.kernel.org/20260809-selftests-thuge-gen-fix-v1-1-1919f4b3d12f@kernel.org
Fixes: 49a4e7186b08 ("selftests/mm: thuge-gen: add setup of HugeTLB pages")
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.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/thuge-gen.c |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

--- a/tools/testing/selftests/mm/thuge-gen.c~selftests-mm-thuge-gen-fix-test_shmget-for-page_size-check
+++ a/tools/testing/selftests/mm/thuge-gen.c
@@ -71,12 +71,16 @@ void test_mmap(unsigned long size, unsig
 
 void test_shmget(unsigned long size, unsigned flags)
 {
-	int id;
-	unsigned long before, after;
+	/* values for PAGE_SIZE test */
+	unsigned long before = NUM_PAGES;
+	unsigned long after = 0;
 	struct shm_info i;
 	char *map;
+	int id;
+
+	if (size != getpagesize())
+		before = hugetlb_free_pages(size);
 
-	before = hugetlb_free_pages(size);
 	id = shmget(IPC_PRIVATE, size * NUM_PAGES, IPC_CREAT|0600|flags);
 	if (id < 0) {
 		if (errno == EPERM) {
@@ -97,10 +101,11 @@ void test_shmget(unsigned long size, uns
 	shmctl(id, IPC_RMID, NULL);
 
 	memset(map, 0xff, size*NUM_PAGES);
-	after = hugetlb_free_pages(size);
+	if (size != getpagesize())
+		after = hugetlb_free_pages(size);
 
 	show(size);
-	ksft_test_result(size == getpagesize() || (before - after) == NUM_PAGES,
+	ksft_test_result((before - after) == NUM_PAGES,
 			 "%s: mmap %lu %x\n", __func__, size, flags);
 	if (shmdt(map))
 		ksft_exit_fail_msg("%s: shmdt: %s\n", __func__, strerror(errno));
_

Patches currently in -mm which might be from rppt@kernel.org are

selftests-mm-thuge-gen-fix-test_shmget-for-page_size-check.patch
drivers-base-mm-move-arch_numac-to-mm.patch
sh-remove-config_numa-and-realted-configuration-options.patch
sh-mm-remove-numac.patch
sh-mm-drop-allocate_pgdat.patch
sh-remove-setup_bootmem_node-and-plat_mem_setup.patch
sh-drop-dead-code-guarded-by-ifdef-config_numa.patch
sh-drop-include-asm-mmzoneh.patch
init-kconfig-drop-arch_want_numa_variable_locality.patch
sh-init-remove-call-the-memblock_set_node.patch
sh-remove-sparsemem-related-entries-from-kconfig.patch
sh-drop-include-asm-sparsememh.patch