| From: |
| Axel Rasmussen <axelrasmussen-AT-google.com> |
| To: |
| Alexander Viro <viro-AT-zeniv.linux.org.uk>, Andrea Arcangeli <aarcange-AT-redhat.com>, Andrew Morton <akpm-AT-linux-foundation.org>, Hugh Dickins <hughd-AT-google.com>, Jerome Glisse <jglisse-AT-redhat.com>, Joe Perches <joe-AT-perches.com>, Lokesh Gidra <lokeshgidra-AT-google.com>, Mike Rapoport <rppt-AT-linux.vnet.ibm.com>, Peter Xu <peterx-AT-redhat.com>, Shaohua Li <shli-AT-fb.com>, Shuah Khan <shuah-AT-kernel.org>, Wang Qing <wangqing-AT-vivo.com> |
| Subject: |
| [PATCH 0/5] userfaultfd: support minor fault handling for shmem |
| Date: |
| Wed, 24 Feb 2021 18:14:15 -0800 |
| Message-ID: |
| <20210225021420.2290912-1-axelrasmussen@google.com> |
| Cc: |
| linux-kernel-AT-vger.kernel.org, linux-fsdevel-AT-vger.kernel.org, linux-mm-AT-kvack.org, linux-kselftest-AT-vger.kernel.org, Axel Rasmussen <axelrasmussen-AT-google.com>, Cannon Matthews <cannonmatthews-AT-google.com>, "Dr . David Alan Gilbert" <dgilbert-AT-redhat.com>, David Rientjes <rientjes-AT-google.com>, Michel Lespinasse <walken-AT-google.com>, Mina Almasry <almasrymina-AT-google.com>, Oliver Upton <oupton-AT-google.com> |
| Archive-link: |
| Article |
Base
====
This series is based on top of my series which adds minor fault handling for
hugetlbfs [1]. (And, therefore, it is based on linux-next/akpm and Peter Xu's
series for disabling huge pmd sharing as well.)
[1] https://lore.kernel.org/patchwork/cover/1384095/
Overview
========
See my original series linked above for a detailed overview of minor fault
handling in general. The feature in this series works exactly like the
hugetblfs version (from userspace's perspective).
I'm sending this as a separate series because:
- The original minor fault handling series has been through several rounds of
review and seems close to being merged, so it seems reasonable to start
looking at this next step.
- shmem is different enough that this series may require some additional work
before it's ready, and I don't want to delay the original series
unnecessarily by bundling them together.
Use Case
========
In some cases it is useful to have VM memory backed by tmpfs instead of
hugetlbfs. So, this feature will be used to support the same VM live migration
use case described in my original series.
Additionally, Android folks (Lokesh Gidra <lokeshgidra@google.com>) hope to
optimize the Android JVM garbage collector using this feature (a paper
describing a somewhat similar approach: https://arxiv.org/pdf/1902.04738.pdf).
Axel Rasmussen (5):
userfaultfd: support minor fault handling for shmem
userfaultfd/selftests: use memfd_create for shmem test type
userfaultfd/selftests: create alias mappings in the shmem test
userfaultfd/selftests: reinitialize test context in each test
userfaultfd/selftests: exercise minor fault handling shmem support
fs/userfaultfd.c | 6 +-
include/linux/shmem_fs.h | 26 +-
include/uapi/linux/userfaultfd.h | 4 +-
mm/memory.c | 8 +-
mm/shmem.c | 88 +++----
mm/userfaultfd.c | 27 +-
tools/testing/selftests/vm/userfaultfd.c | 322 +++++++++++++++--------
7 files changed, 293 insertions(+), 188 deletions(-)
--
2.30.0.617.g56c4b15f3c-goog
