linux-kernel - [PATCH 0/3] Add hugetlb MADV

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20220128222605.66828-1-mike.kravetz@oracle.com>
Date:   Fri, 28 Jan 2022 14:26:02 -0800
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     Naoya Horiguchi <naoya.horiguchi@...ux.dev>,
        David Hildenbrand <david@...hat.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Mina Almasry <almasrymina@...gle.com>,
        Michal Hocko <mhocko@...e.com>, Peter Xu <peterx@...hat.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Shuah Khan <shuah@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>
Subject: [PATCH 0/3] Add hugetlb MADV_DONTNEED support

Userfaultfd selftests for hugetlb does not perform UFFD_EVENT_REMAP
testing.  However, mremap support was recently added in commit
550a7d60bd5e ("mm, hugepages: add mremap() support for hugepage backed
vma").  While attempting to enable mremap support in the test, it was
discovered that the mremap test indirectly depends on MADV_DONTNEED.

madvise does not allow MADV_DONTNEED for hugetlb mappings.  However,
that is primarily due to the check in can_madv_lru_vma().  By simply
removing the check and adding huge page alignment, MADV_DONTNEED can
be made to work for hugetlb mappings.

Do note that there is no compelling use case for adding this support.
This was discussed in the RFC [1].  However, adding support makes sense
as it is fairly trivial and brings hugetlb functionality more in line
with 'normal' memory.

After enabling support, add selftest for MADV_DONTNEED as well as
MADV_REMOVE.  Then update userfaultfd selftest.

RFC -> v1
- Fixed alignment issues when calling zap_page_range.  Naoya
- Added checks for invalid arguments and misalignment to selftest.

Mike Kravetz (3):
  mm: enable MADV_DONTNEED for hugetlb mappings
  selftests/vm: add hugetlb madvise MADV_DONTNEED MADV_REMOVE test
  userfaultfd/selftests: enable huegtlb remap and remove event testing

 mm/madvise.c                                 |  24 +-
 tools/testing/selftests/vm/Makefile          |   1 +
 tools/testing/selftests/vm/hugetlb-madvise.c | 401 +++++++++++++++++++
 tools/testing/selftests/vm/run_vmtests.sh    |  12 +
 tools/testing/selftests/vm/userfaultfd.c     |  67 ++--
 5 files changed, 470 insertions(+), 35 deletions(-)
 create mode 100644 tools/testing/selftests/vm/hugetlb-madvise.c

-- 
2.34.1