selftests/mm: remove obsolete hugetlb vmemmap test

The hugetlb vmemmap selftest was added to check the old HVO layout where
tail vmemmap pages reused the head page.  That assumption no longer
matches the current HVO mapping layout.

HVO now keeps a private backing page for the head vmemmap page and remaps
redundant tail vmemmap pages to a shared read-only backing page.  The old
page flag check is therefore testing an obsolete implementation detail
rather than the current ABI or behavior.

Remove the stale test and its build and run entries.

[akpm@linux-foundation.org: don't clean old executables out of .gitignore]
  Link: https://lore.kernel.org/CAHk-=wiHK5_oBUdUiNAaevmN9f-ORe+QBqbRefAZaw-RbgEn3w@mail.gmail.com
Link: https://lore.kernel.org/20260710092427.3459121-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: SJ Park <sj@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
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>

3 files changed, 0 insertions, 134 deletions

diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
index e6df968f0971..277a141d662e 100644
--- a/tools/testing/selftests/mm/Makefile
+++ b/tools/testing/selftests/mm/Makefile
@@ -66,7 +66,6 @@ TEST_GEN_FILES += hugetlb-mremap
 TEST_GEN_FILES += hugetlb-read-hwpoison
 TEST_GEN_FILES += hugetlb-shm
 TEST_GEN_FILES += hugetlb-soft-offline
-TEST_GEN_FILES += hugetlb-vmemmap
 TEST_GEN_FILES += khugepaged
 TEST_GEN_FILES += madv_populate
 TEST_GEN_FILES += map_fixed_noreplace
diff --git a/tools/testing/selftests/mm/hugetlb-vmemmap.c b/tools/testing/selftests/mm/hugetlb-vmemmap.c
deleted file mode 100644
index 507df78a158d..000000000000
--- a/tools/testing/selftests/mm/hugetlb-vmemmap.c
+++ /dev/null
@@ -1,132 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * A test case of using hugepage memory in a user application using the
- * mmap system call with MAP_HUGETLB flag.  Before running this program
- * make sure the administrator has allocated enough default sized huge
- * pages to cover the 2 MB allocation.
- */
-#include <stdlib.h>
-#include <stdio.h>
-#include <unistd.h>
-#include <sys/mman.h>
-#include <fcntl.h>
-#include "vm_util.h"
-#include "hugepage_settings.h"
-
-#define PAGE_COMPOUND_HEAD	(1UL << 15)
-#define PAGE_COMPOUND_TAIL	(1UL << 16)
-#define PAGE_HUGE		(1UL << 17)
-
-#define HEAD_PAGE_FLAGS		(PAGE_COMPOUND_HEAD | PAGE_HUGE)
-#define TAIL_PAGE_FLAGS		(PAGE_COMPOUND_TAIL | PAGE_HUGE)
-
-#define PM_PFRAME_BITS		55
-#define PM_PFRAME_MASK		~((1UL << PM_PFRAME_BITS) - 1)
-
-static size_t pagesize;
-static size_t maplength;
-
-static void write_bytes(char *addr, size_t length)
-{
-	unsigned long i;
-
-	for (i = 0; i < length; i++)
-		*(addr + i) = (char)i;
-}
-
-static unsigned long virt_to_pfn(void *addr)
-{
-	int fd;
-	unsigned long pagemap;
-
-	fd = open("/proc/self/pagemap", O_RDONLY);
-	if (fd < 0)
-		return -1UL;
-
-	lseek(fd, (unsigned long)addr / pagesize * sizeof(pagemap), SEEK_SET);
-	read(fd, &pagemap, sizeof(pagemap));
-	close(fd);
-
-	return pagemap & ~PM_PFRAME_MASK;
-}
-
-static int check_page_flags(unsigned long pfn)
-{
-	int fd, i;
-	unsigned long pageflags;
-
-	fd = open("/proc/kpageflags", O_RDONLY);
-	if (fd < 0)
-		return -1;
-
-	lseek(fd, pfn * sizeof(pageflags), SEEK_SET);
-
-	read(fd, &pageflags, sizeof(pageflags));
-	if ((pageflags & HEAD_PAGE_FLAGS) != HEAD_PAGE_FLAGS) {
-		close(fd);
-		ksft_print_msg("Head page flags (%lx) is invalid\n", pageflags);
-		return -1;
-	}
-
-	/*
-	 * pages other than the first page must be tail and shouldn't be head;
-	 * this also verifies kernel has correctly set the fake page_head to tail
-	 * while hugetlb_free_vmemmap is enabled.
-	 */
-	for (i = 1; i < maplength / pagesize; i++) {
-		read(fd, &pageflags, sizeof(pageflags));
-		if ((pageflags & TAIL_PAGE_FLAGS) != TAIL_PAGE_FLAGS ||
-		    (pageflags & HEAD_PAGE_FLAGS) == HEAD_PAGE_FLAGS) {
-			close(fd);
-			ksft_print_msg("Tail page flags (%lx) is invalid\n", pageflags);
-			return -1;
-		}
-	}
-
-	close(fd);
-
-	return 0;
-}
-
-int main(int argc, char **argv)
-{
-	void *addr;
-	unsigned long pfn;
-	int ret;
-
-	ksft_print_header();
-	ksft_set_plan(1);
-
-	if (!hugetlb_setup_default(1))
-		ksft_exit_skip("Not enough free huge pages\n");
-
-	pagesize  = psize();
-	maplength = default_huge_page_size();
-	if (!maplength)
-		ksft_exit_skip("Unable to determine huge page size\n");
-
-	addr = mmap(NULL, maplength, PROT_READ | PROT_WRITE,
-			MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0);
-	if (addr == MAP_FAILED)
-		ksft_exit_fail_perror("mmap");
-
-	/* Trigger allocation of HugeTLB page. */
-	write_bytes(addr, maplength);
-
-	pfn = virt_to_pfn(addr);
-	if (pfn == -1UL) {
-		ksft_perror("virt_to_pfn");
-		munmap(addr, maplength);
-		ksft_exit_fail();
-	}
-
-	ksft_print_msg("Returned address is %p whose pfn is %lx\n", addr, pfn);
-
-	ret = check_page_flags(pfn);
-
-	if (munmap(addr, maplength))
-		ksft_exit_fail_perror("munmap");
-
-	ksft_test_result(!ret, "HugeTLB vmemmap page flags\n");
-	ksft_finished();
-}
diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index 8c296dedf047..a60b9f9f16e7 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -262,7 +262,6 @@ echo "TAP version 13" | tap_output
 CATEGORY="hugetlb" run_test ./hugetlb-mmap
 CATEGORY="hugetlb" run_test ./hugetlb-shm
 CATEGORY="hugetlb" run_test ./hugetlb-mremap
-CATEGORY="hugetlb" run_test ./hugetlb-vmemmap
 CATEGORY="hugetlb" run_test ./hugetlb-madvise
 CATEGORY="hugetlb" run_test ./hugetlb_dio
 CATEGORY="hugetlb" run_test ./hugetlb_fault_after_madv