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Date:   Thu,  6 Jul 2023 15:50:28 -0700
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Message-ID: <20230706225037.1164380-1-axelrasmussen@google.com>
Subject: [PATCH v3 0/8] add UFFDIO_POISON to simulate memory poisoning with UFFD
From:   Axel Rasmussen <axelrasmussen@google.com>
To:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Brian Geffon <bgeffon@google.com>,
        Christian Brauner <brauner@kernel.org>,
        David Hildenbrand <david@redhat.com>,
        Gaosheng Cui <cuigaosheng1@huawei.com>,
        Huang Ying <ying.huang@intel.com>,
        Hugh Dickins <hughd@google.com>,
        James Houghton <jthoughton@google.com>,
        "Jan Alexander Steffens (heftig)" <heftig@archlinux.org>,
        Jiaqi Yan <jiaqiyan@google.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Kefeng Wang <wangkefeng.wang@huawei.com>,
        "Liam R. Howlett" <Liam.Howlett@oracle.com>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        "Mike Rapoport (IBM)" <rppt@kernel.org>,
        Muchun Song <muchun.song@linux.dev>,
        Nadav Amit <namit@vmware.com>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        Peter Xu <peterx@redhat.com>,
        Ryan Roberts <ryan.roberts@arm.com>,
        Shuah Khan <shuah@kernel.org>,
        Suleiman Souhlal <suleiman@google.com>,
        Suren Baghdasaryan <surenb@google.com>,
        "T.J. Alumbaugh" <talumbau@google.com>,
        Yu Zhao <yuzhao@google.com>,
        ZhangPeng <zhangpeng362@huawei.com>
Cc:     linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
        linux-kselftest@vger.kernel.org,
        Axel Rasmussen <axelrasmussen@google.com>
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Precedence: bulk

This series adds a new userfaultfd feature, UFFDIO_POISON. See commit 4
for a detailed description of the feature.

The series is based on Linus master (partial 6.5 merge window), and
structured like this:

- Patches 1-3 are preparation / refactoring
- Patches 4-6 implement and advertise the new feature
- Patches 7-8 implement a unit test for the new feature

Changelog:

v2 -> v3:
 - Rebase onto current Linus master.
 - Don't overwrite existing PTE markers for non-hugetlb UFFDIO_POISON.
   Before, non-hugetlb would override them, but hugetlb would not. I don't
   think there's a use case where we *want* to override a UFFD_WP marker
   for example, so take the more conservative behavior for all kinds of
   memory.
 - [Peter] Drop hugetlb mfill atomic refactoring, since it isn't needed
   for this series (we don't touch that code directly anyway).
 - [Peter] Switch to re-using PTE_MARKER_SWAPIN_ERROR instead of defining
   new PTE_MARKER_UFFD_POISON.
 - [Peter] Extract start / len range overflow check into existing
   validate_range helper; this fixes the style issue of unnecessary braces
   in the UFFDIO_POISON implementation, because this code is just deleted.
 - [Peter] Extract file size check out into a new helper.
 - [Peter] Defer actually "enabling" the new feature until the last commit
   in the series; combine this with adding the documentation. As a
   consequence, move the selftest commits after this one.
 - [Randy] Fix typo in documentation.

v1 -> v2:
 - [Peter] Return VM_FAULT_HWPOISON not VM_FAULT_SIGBUS, to yield the
   correct behavior for KVM (guest MCE).
 - [Peter] Rename UFFDIO_SIGBUS to UFFDIO_POISON.
 - [Peter] Implement hugetlbfs support for UFFDIO_POISON.

Axel Rasmussen (8):
  mm: make PTE_MARKER_SWAPIN_ERROR more general
  mm: userfaultfd: check for start + len overflow in validate_range
  mm: userfaultfd: extract file size check out into a helper
  mm: userfaultfd: add new UFFDIO_POISON ioctl
  mm: userfaultfd: support UFFDIO_POISON for hugetlbfs
  mm: userfaultfd: document and enable new UFFDIO_POISON feature
  selftests/mm: refactor uffd_poll_thread to allow custom fault handlers
  selftests/mm: add uffd unit test for UFFDIO_POISON

 Documentation/admin-guide/mm/userfaultfd.rst |  15 +++
 fs/userfaultfd.c                             |  73 ++++++++++--
 include/linux/mm_inline.h                    |  19 +++
 include/linux/swapops.h                      |  10 +-
 include/linux/userfaultfd_k.h                |   4 +
 include/uapi/linux/userfaultfd.h             |  25 +++-
 mm/hugetlb.c                                 |  51 ++++++--
 mm/madvise.c                                 |   2 +-
 mm/memory.c                                  |  15 ++-
 mm/mprotect.c                                |   4 +-
 mm/shmem.c                                   |   4 +-
 mm/swapfile.c                                |   2 +-
 mm/userfaultfd.c                             |  83 ++++++++++---
 tools/testing/selftests/mm/uffd-common.c     |   5 +-
 tools/testing/selftests/mm/uffd-common.h     |   3 +
 tools/testing/selftests/mm/uffd-stress.c     |  12 +-
 tools/testing/selftests/mm/uffd-unit-tests.c | 117 +++++++++++++++++++
 17 files changed, 377 insertions(+), 67 deletions(-)

--
2.41.0.255.g8b1d071c50-goog