+ selftests-mm-fix-mmap-return-value-check-in-run_migration_benchmark.patch added to mm-new branch

+ selftests-mm-fix-mmap-return-value-check-in-run_migration_benchmark.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: selftests/mm: fix mmap() return value check in run_migration_benchmark
has been added to the -mm mm-new branch.  Its filename is
     selftests-mm-fix-mmap-return-value-check-in-run_migration_benchmark.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-mm-fix-mmap-return-value-check-in-run_migration_benchmark.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

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days

------------------------------------------------------
From: Hongfu Li <lihongfu@kylinos.cn>
Subject: selftests/mm: fix mmap() return value check in run_migration_benchmark
Date: Tue, 12 May 2026 18:13:05 +0800

mmap() returns MAP_FAILED on error, not NULL.  The current check uses
!buffer->ptr, which evaluates to false when mmap() fails (since MAP_FAILED
is (void *)-1, not 0), so the error path is never taken.

Link: https://lore.kernel.org/20260512101305.139509-1-lihongfu@kylinos.cn
Signed-off-by: Hongfu Li <lihongfu@kylinos.cn>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Donet Tom <donettom@linux.ibm.com>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 tools/testing/selftests/mm/hmm-tests.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/tools/testing/selftests/mm/hmm-tests.c~selftests-mm-fix-mmap-return-value-check-in-run_migration_benchmark
+++ a/tools/testing/selftests/mm/hmm-tests.c
@@ -2740,7 +2740,7 @@ static inline int run_migration_benchmar
 	buffer->ptr = mmap(NULL, buffer_size, PROT_READ | PROT_WRITE,
 			  MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 
-	if (!buffer->ptr)
+	if (buffer->ptr == MAP_FAILED)
 		return -1;
 
 	/* Apply THP hint if requested */
_

Patches currently in -mm which might be from lihongfu@kylinos.cn are

selftests-mm-fix-mmap-return-value-check-in-run_migration_benchmark.patch