Patch "selftests/mm: ksm_tests should only MADV_HUGEPAGE valid memory" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    selftests/mm: ksm_tests should only MADV_HUGEPAGE valid memory

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     selftests-mm-ksm_tests-should-only-madv_hugepage-val.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 184f6031f1413b0ebee254c411193bdb8e49742a
Author: Ryan Roberts <ryan.roberts@xxxxxxx>
Date:   Mon Jan 22 12:05:54 2024 +0000

    selftests/mm: ksm_tests should only MADV_HUGEPAGE valid memory
    
    [ Upstream commit d021b442cf312664811783e92b3d5e4548e92a53 ]
    
    ksm_tests was previously mmapping a region of memory, aligning the
    returned pointer to a PMD boundary, then setting MADV_HUGEPAGE, but was
    setting it past the end of the mmapped area due to not taking the pointer
    alignment into consideration.  Fix this behaviour.
    
    Up until commit efa7df3e3bb5 ("mm: align larger anonymous mappings on THP
    boundaries"), this buggy behavior was (usually) masked because the
    alignment difference was always less than PMD-size.  But since the
    mentioned commit, `ksm_tests -H -s 100` started failing.
    
    Link: https://lkml.kernel.org/r/20240122120554.3108022-1-ryan.roberts@xxxxxxx
    Fixes: 325254899684 ("selftests: vm: add KSM huge pages merging time test")
    Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
    Cc: Pedro Demarchi Gomes <pedrodemargomes@xxxxxxxxx>
    Cc: Shuah Khan <shuah@xxxxxxxxxx>
    Cc: <stable@xxxxxxxxxxxxxxx>
    Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/tools/testing/selftests/vm/ksm_tests.c b/tools/testing/selftests/vm/ksm_tests.c
index 0d85be2350fa..a81165930785 100644
--- a/tools/testing/selftests/vm/ksm_tests.c
+++ b/tools/testing/selftests/vm/ksm_tests.c
@@ -470,7 +470,7 @@ static int ksm_merge_hugepages_time(int mapping, int prot, int timeout, size_t m
 	if (map_ptr_orig == MAP_FAILED)
 		err(2, "initial mmap");
 
-	if (madvise(map_ptr, len + HPAGE_SIZE, MADV_HUGEPAGE))
+	if (madvise(map_ptr, len, MADV_HUGEPAGE))
 		err(2, "MADV_HUGEPAGE");
 
 	pagemap_fd = open("/proc/self/pagemap", O_RDONLY);