+ selftests-mm-retry-migration-failures-for-the-full-runtime.patch added to mm-new branch

The patch titled
     Subject: selftests/mm: retry migration failures for the full runtime
has been added to the -mm mm-new branch.  Its filename is
     selftests-mm-retry-migration-failures-for-the-full-runtime.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-mm-retry-migration-failures-for-the-full-runtime.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: retry migration failures for the full runtime
Date: Mon, 27 Jul 2026 10:52:21 +0100

move_pages() is best effort and can temporarily fail when concurrent
faults race with page unmapping.  A busy shared-anon workload can exhaust
the current 100 retries long before the intended 20-second runtime and
produce a false failure.

Use the full runtime as the retry window.  Since the initial page location
is unknown, require it to reach both alternating NUMA targets to confirm
that cross-node migration made progress despite transient contention.

Link: https://lore.kernel.org/[email protected]
Signed-off-by: Muhammad Usama Anjum <[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: Sarthak Sharma <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Usama Arif <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 tools/testing/selftests/mm/migration.c |   37 ++++++++++++-----------
 1 file changed, 20 insertions(+), 17 deletions(-)

--- a/tools/testing/selftests/mm/migration.c~selftests-mm-retry-migration-failures-for-the-full-runtime
+++ a/tools/testing/selftests/mm/migration.c
@@ -7,7 +7,7 @@
 #include "kselftest_harness.h"
 #include "hugepage_settings.h"
 
-#include <strings.h>
+#include <string.h>
 #include <pthread.h>
 #include <numa.h>
 #include <numaif.h>
@@ -20,7 +20,6 @@
 
 #define TWOMEG		(2<<20)
 #define RUNTIME		(20)
-#define MAX_RETRIES	100
 #define ALIGN(x, a)	(((x) + (a - 1)) & (~((a) - 1)))
 
 HUGETLB_SETUP_DEFAULT_PAGES(1)
@@ -110,7 +109,7 @@ int migrate(uint64_t *ptr, int n1, int n
 	int ret, tmp;
 	int status = 0;
 	struct timespec ts1, ts2;
-	int failures = 0;
+	int success = 0;
 
 	if (clock_gettime(CLOCK_MONOTONIC, &ts1))
 		return -1;
@@ -119,29 +118,33 @@ int migrate(uint64_t *ptr, int n1, int n
 		if (clock_gettime(CLOCK_MONOTONIC, &ts2))
 			return -1;
 
-		if (ts2.tv_sec - ts1.tv_sec >= RUNTIME)
-			return 0;
+		if (ts2.tv_sec - ts1.tv_sec >= RUNTIME) {
+			/* Reaching both targets verifies a cross-node move. */
+			if (success >= 2)
+				return 0;
+			else
+				return -2;
+		}
 
 		ret = move_pages(0, 1, (void **) &ptr, &n2, &status,
 				MPOL_MF_MOVE_ALL);
-		if (ret) {
-			if (ret > 0) {
-				/* Migration is best effort; try again */
-				if (++failures < MAX_RETRIES)
-					continue;
-				printf("Didn't migrate %d pages\n", ret);
-			}
-			else
-				perror("Couldn't migrate pages");
+		if (ret < 0) {
+			perror("Couldn't migrate pages");
+			return ret;
+		}
+		/* Migration is best effort. Try again */
+		if (ret > 0 || status < 0)
+			continue;
+		if (status != n2) {
+			printf("Page is on node %d instead of target node %d\n",
+			       status, n2);
 			return -2;
 		}
-		failures = 0;
+		success++;
 		tmp = n2;
 		n2 = n1;
 		n1 = tmp;
 	}
-
-	return 0;
 }
 
 void *access_mem(void *ptr)
_

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