+ tools-testing-selftests-test-relocate-anon-in-split-huge-page-test.patch added to mm-new branch

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

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The patch titled
     Subject: tools/testing/selftests: test relocate anon in split huge page test
has been added to the -mm mm-new branch.  Its filename is
     tools-testing-selftests-test-relocate-anon-in-split-huge-page-test.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/tools-testing-selftests-test-relocate-anon-in-split-huge-page-test.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
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------------------------------------------------------
From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Subject: tools/testing/selftests: test relocate anon in split huge page test
Date: Mon, 9 Jun 2025 14:26:44 +0100

It's useful to explicitly test splitting of huge pages with
MREMAP_RELOCATE_ANON set, as this exercises the undo logic and ensures
that it functions correctly.

Expand the tests to do so in the instance where anon mremap() occurs, and
utilise the shared sys_mremap() function to allow for specification of the
new mremap flag (which would otherwise be filtered by glibc).

Link: https://lkml.kernel.org/r/064971308aacfbdaaf404ebe5736666744dbd005.1749473726.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jakub Matěna <matenajakub@gmail.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 tools/testing/selftests/mm/split_huge_page_test.c |   25 ++++++++----
 1 file changed, 17 insertions(+), 8 deletions(-)

--- a/tools/testing/selftests/mm/split_huge_page_test.c~tools-testing-selftests-test-relocate-anon-in-split-huge-page-test
+++ a/tools/testing/selftests/mm/split_huge_page_test.c
@@ -19,6 +19,7 @@
 #include <malloc.h>
 #include <stdbool.h>
 #include <time.h>
+#include <linux/mman.h>
 #include "vm_util.h"
 #include "../kselftest.h"
 
@@ -180,7 +181,7 @@ void split_pmd_thp_to_order(int order)
 	free(one_page);
 }
 
-void split_pte_mapped_thp(void)
+void split_pte_mapped_thp(bool relocate_anon)
 {
 	char *one_page, *pte_mapped, *pte_mapped2;
 	size_t len = 4 * pmd_pagesize;
@@ -221,10 +222,14 @@ void split_pte_mapped_thp(void)
 
 	/* remap the Nth pagesize of Nth THP */
 	for (i = 1; i < 4; i++) {
-		pte_mapped2 = mremap(one_page + pmd_pagesize * i + pagesize * i,
-				     pagesize, pagesize,
-				     MREMAP_MAYMOVE|MREMAP_FIXED,
-				     pte_mapped + pagesize * i);
+		int mremap_flags = MREMAP_MAYMOVE|MREMAP_FIXED;
+
+		if (relocate_anon)
+			mremap_flags |= MREMAP_RELOCATE_ANON;
+
+		pte_mapped2 = sys_mremap(one_page + pmd_pagesize * i + pagesize * i,
+					 pagesize, pagesize, mremap_flags,
+					 pte_mapped + pagesize * i);
 		if (pte_mapped2 == MAP_FAILED)
 			ksft_exit_fail_msg("mremap failed: %s\n", strerror(errno));
 	}
@@ -257,7 +262,10 @@ void split_pte_mapped_thp(void)
 	if (thp_size)
 		ksft_exit_fail_msg("Still %ld THPs not split\n", thp_size);
 
-	ksft_test_result_pass("Split PTE-mapped huge pages successful\n");
+	if (relocate_anon)
+		ksft_test_result_pass("Split PTE-mapped huge pages w/MREMAP_RELOCATE_ANON successful\n");
+	else
+		ksft_test_result_pass("Split PTE-mapped huge pages successful\n");
 	munmap(one_page, len);
 	close(pagemap_fd);
 	close(kpageflags_fd);
@@ -534,7 +542,7 @@ int main(int argc, char **argv)
 	if (argc > 1)
 		optional_xfs_path = argv[1];
 
-	ksft_set_plan(1+8+1+9+9+8*4+2);
+	ksft_set_plan(1+8+1+1+9+9+8*4+2);
 
 	pagesize = getpagesize();
 	pageshift = ffs(pagesize) - 1;
@@ -550,7 +558,8 @@ int main(int argc, char **argv)
 		if (i != 1)
 			split_pmd_thp_to_order(i);
 
-	split_pte_mapped_thp();
+	split_pte_mapped_thp(/* relocate_anon= */false);
+	split_pte_mapped_thp(/* relocate_anon= */true);
 	for (i = 0; i < 9; i++)
 		split_file_backed_thp(i);
 
_

Patches currently in -mm which might be from lorenzo.stoakes@oracle.com are

mm-vma-reset-vma-iterator-on-commit_merge-oom-failure.patch
mm-add-mmap_prepare-compatibility-layer-for-nested-file-systems.patch
mm-add-mmap_prepare-compatibility-layer-for-nested-file-systems-fix-2.patch
docs-mm-expand-vma-doc-to-highlight-pte-freeing-non-vma-traversal.patch
mm-ksm-have-ksm-vma-checks-not-require-a-vma-pointer.patch
mm-ksm-refer-to-special-vmas-via-vm_special-in-ksm_compatible.patch
mm-prevent-ksm-from-breaking-vma-merging-for-new-vmas.patch
tools-testing-selftests-add-vma-merge-tests-for-ksm-merge.patch
mm-pagewalk-split-walk_page_range_novma-into-kernel-user-parts.patch
mm-mremap-introduce-more-mergeable-mremap-via-mremap_relocate_anon.patch
mm-mremap-add-mremap_must_relocate_anon.patch
mm-mremap-add-mremap_relocate_anon-support-for-large-folios.patch
tools-uapi-update-copy-of-linux-mmanh-from-the-kernel-sources.patch
tools-testing-selftests-add-sys_mremap-helper-to-vm_utilh.patch
tools-testing-selftests-add-mremap-cases-that-merge-normally.patch
tools-testing-selftests-add-mremap_relocate_anon-merge-test-cases.patch
tools-testing-selftests-expand-mremap-tests-for-mremap_relocate_anon.patch
tools-testing-selftests-have-cow-self-test-use-mremap_relocate_anon.patch
tools-testing-selftests-test-relocate-anon-in-split-huge-page-test.patch
tools-testing-selftests-add-mremap_relocate_anon-fork-tests.patch