+ selftests-mm-skip-cow-tmpfile-cases-when-fallocate-is-unsupported.patch added to mm-new branch

The patch titled
     Subject: selftests/mm: skip COW tmpfile cases when fallocate() is unsupported
has been added to the -mm mm-new branch.  Its filename is
     selftests-mm-skip-cow-tmpfile-cases-when-fallocate-is-unsupported.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-mm-skip-cow-tmpfile-cases-when-fallocate-is-unsupported.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: Muhammad Usama Anjum <[email protected]>
Subject: selftests/mm: skip COW tmpfile cases when fallocate() is unsupported
Date: Mon, 27 Jul 2026 10:52:17 +0100

Patch series "selftests/mm: Handle unsupported and transient test
conditions", v3.

Several MM selftests report failures when the test environment lacks
an underlying prerequisite, such as fallocate() support, MADV_REMOVE,
local page-cache semantics, or swap.

This series converts those unsupported cases to SKIP while preserving
failures for unexpected errors. It also allows migration tests to retry
transient move_pages() failures.


This patch (of 5):

The tmpfile-backed COW cases allocate a one-page file with fallocate()
before exercising private and shared mappings.  When the filesystem
backing tmpfile() does not implement fallocate(), setup fails with
EOPNOTSUPP and no COW behavior is exercised.

This occurs when the temporary directory resides on a filesystem with
limited allocation support, such as NFSv3.  Reporting a failure adds noise
because the test prerequisite is absent rather than the COW implementation
being broken.

Report EOPNOTSUPP as a skip.  Continue treating every other fallocate()
error as a failure so unexpected setup regressions remain visible.

Link: https://lore.kernel.org/[email protected]
Link: https://lore.kernel.org/[email protected]
Signed-off-by: Muhammad Usama Anjum <[email protected]>
Tested-by: Sarthak Sharma <[email protected]>
Acked-by: Usama Arif <[email protected]>
Cc: Baolin Wang <[email protected]>
Cc: Barry Song <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Dev Jain <[email protected]>
Cc: Lance Yang <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: Miaohe Lin <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: Nico Pache <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 tools/testing/selftests/mm/cow.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/tools/testing/selftests/mm/cow.c~selftests-mm-skip-cow-tmpfile-cases-when-fallocate-is-unsupported
+++ a/tools/testing/selftests/mm/cow.c
@@ -1718,8 +1718,13 @@ static void run_with_tmpfile(non_anon_te
 
 	/* File consists of a single page filled with zeroes. */
 	if (fallocate(fd, 0, 0, pagesize)) {
-		ksft_perror("fallocate() failed");
-		log_test_result(KSFT_FAIL);
+		if (errno == EOPNOTSUPP) {
+			ksft_print_msg("fallocate() not supported by filesystem\n");
+			log_test_result(KSFT_SKIP);
+		} else {
+			ksft_perror("fallocate() failed");
+			log_test_result(KSFT_FAIL);
+		}
 		goto close;
 	}
 
_

Patches currently in -mm which might be from [email protected] are

selftests-mm-unpoison-pages-in-memory-failure-teardown.patch
selftests-mm-skip-cow-tmpfile-cases-when-fallocate-is-unsupported.patch
selftests-mm-skip-guard-hole-punch-test-if-madv_remove-is-unsupported.patch
selftests-mm-skip-khugepaged-swap-tests-without-swap.patch
selftests-mm-skip-hard-dirty-page-cache-test-on-nfs.patch
selftests-mm-retry-migration-failures-for-the-full-runtime.patch