selftests/mm: ksm_tests should only MADV_HUGEPAGE valid memory

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@arm.com
Fixes: 325254899684 ("selftests: vm: add KSM huge pages merging time test")
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests: mm: ksm: fix incorrect evaluation of parameter

A missing break in kms_tests leads to kselftest hang when the parameter -s
is used.

In current code flow because of missing break in -s, -t parses args
spilled from -s and as -t accepts only valid values as 0,1 so any arg in
-s >1 or <0, gets in ksm_test failure

This went undetected since, before the addition of option -t, the next
case -M would immediately break out of the switch statement but that is no
longer the case

Add the missing break statement.

----Before----
./ksm_tests -H -s 100
Invalid merge type

----After----
./ksm_tests -H -s 100
Number of normal pages: 0
Number of huge pages: 50
Total size: 100 MiB
Total time: 0.401732682 s
Average speed: 248.922 MiB/s

Link: https://lkml.kernel.org/r/20230728163952.4634-1-ayush.jain3@amd.com
Fixes: 07115fcc15b4 ("selftests/mm: add new selftests for KSM")
Signed-off-by: Ayush Jain <ayush.jain3@amd.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Stefan Roesch <shr@devkernel.io>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/mm: add new selftests for KSM

This adds three new tests to the selftests for KSM. These tests use the
new prctl API's to enable and disable KSM.

1) add new prctl flags to prctl header file in tools dir

This adds the new prctl flags to the include file prct.h in the
tools directory. This makes sure they are available for testing.

2) add KSM prctl merge test to ksm_tests

This adds the -t option to the ksm_tests program. The -t flag
allows to specify if it should use madvise or prctl ksm merging.

3) add two functions for debugging merge outcome for ksm_tests

This adds two functions to report the metrics in /proc/self/ksm_stat
and /sys/kernel/debug/mm/ksm. The debug output is enabled with the
-d option.

4) add KSM prctl test to ksm_functional_tests

This adds a test to the ksm_functional_test that verifies that the
prctl system call to enable / disable KSM works.

5) add KSM fork test to ksm_functional_test

Add fork test to verify that the MMF_VM_MERGE_ANY flag is inherited
by the child process.

Link: https://lkml.kernel.org/r/20230418051342.1919757-4-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/mm: merge util.h into vm_util.h

There're two util headers under mm/ kselftest. Merge one with another.
It turns out util.h is the easy one to move.

When merging, drop PAGE_SIZE / PAGE_SHIFT because they're unnecessary
wrappers to page_size() / page_shift(), meanwhile rename them to psize()
and pshift() so as to not conflict with some existing definitions in some
test files that includes vm_util.h.

Link: https://lkml.kernel.org/r/20230412164120.327731-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/vm: rename selftests/vm to selftests/mm

Rename selftets/vm to selftests/mm for being more consistent with the
code, documentation, and tools directories, and won't be confused with
virtual machines.

[sj@kernel.org: convert missing vm->mm changes]
Link: https://lkml.kernel.org/r/20230107230643.252273-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20230103180754.129637-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>