selftests/mm: Fix build with _FORTIFY_SOURCE

Add missing flags argument to open(2) call with O_CREAT.

Some tests fail to compile if _FORTIFY_SOURCE is defined (to any valid
value) (together with -O), resulting in similar error messages such as:

In file included from /usr/include/fcntl.h:342,
from gup_test.c:1:
In function 'open',
inlined from 'main' at gup_test.c:206:10:
/usr/include/bits/fcntl2.h:50:11: error: call to '__open_missing_mode' declared with attribute error: open with O_CREAT or O_TMPFILE in second argument needs 3 arguments
50 | __open_missing_mode ();
| ^~~~~~~~~~~~~~~~~~~~~~

_FORTIFY_SOURCE is enabled by default in some distributions, so the
tests are not built by default and are skipped.

open(2) man-page warns about missing flags argument: "if it is not
supplied, some arbitrary bytes from the stack will be applied as the
file mode."

Link: https://lkml.kernel.org/r/20240318023445.3192922-1-vt@altlinux.org
Fixes: aeb85ed4f41a ("tools/testing/selftests/vm/gup_benchmark.c: allow user specified file")
Fixes: fbe37501b252 ("mm: huge_memory: debugfs for file-backed THP split")
Fixes: c942f5bd17b3 ("selftests: soft-dirty: add test for mprotect")
Signed-off-by: Vitaly Chikunov <vt@altlinux.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Keith Busch <kbusch@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/mm: reuse read_pmd_pagesize() in COW selftest

Patch series "mm: (pte|pmd)_mkdirty() should not unconditionally allow for
write access".

This is the follow-up on [1], adding selftests (testing for known issues
we added workarounds for and other issues that haven't been fixed yet),
fixing sparc64, reverting the workarounds, and perform one cleanup.

The patch from [1] was modified slightly (updated/extended patch
description, dropped one unnecessary NOP instruction from the ASM in
__pte_mkhwwrite()).

Retested on x86_64 and sparc64 (sun4u in QEMU).

I scanned most architectures to make sure their (pte|pmd)_mkdirty()
handling is correct. To be sure, we can run the selftests and find out if
other architectures are still affectes (loongarch was fixed recently as
well).

Based on master for now. I don't expect surprises regarding mm-tress, but
I can rebase if there are any problems.


This patch (of 6):

The COW selftest can deal with THP not being configured. So move error
handling of read_pmd_pagesize() into the callers such that we can reuse it
in the COW selftest.

Link: https://lkml.kernel.org/r/20230411142512.438404-1-david@redhat.com
Link: https://lkml.kernel.org/r/20221212130213.136267-1-david@redhat.com [1]
Link: https://lkml.kernel.org/r/20230411142512.438404-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Yu Zhao <yuzhao@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>