From: Peter Xu <peterx@redhat.com>
To: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>,
Suren Baghdasaryan <surenb@google.com>,
akpm@linux-foundation.org, viro@zeniv.linux.org.uk,
brauner@kernel.org, shuah@kernel.org, aarcange@redhat.com,
lokeshgidra@google.com, hughd@google.com, mhocko@suse.com,
axelrasmussen@google.com, rppt@kernel.org, willy@infradead.org,
Liam.Howlett@oracle.com, zhangpeng362@huawei.com,
bgeffon@google.com, kaleshsingh@google.com, ngeoffray@google.com,
jdduke@google.com, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org, kernel-team@android.com
Subject: Re: [PATCH v2 2/3] userfaultfd: UFFDIO_REMAP uABI
Date: Mon, 2 Oct 2023 11:21:20 -0400 [thread overview]
Message-ID: <ZRrf8NligMzwqx97@x1n> (raw)
In-Reply-To: <fc27ce41-bc97-91a7-deb6-67538689021c@redhat.com>
On Mon, Oct 02, 2023 at 10:00:03AM +0200, David Hildenbrand wrote:
> In case we cannot simply remap the page, the fallback sequence (from the
> cover letter) would be triggered.
>
> 1) UFFDIO_COPY
> 2) MADV_DONTNEED
>
> So we would just handle the operation internally without a fallback.
Note that I think there will be a slight difference on whole remap
atomicity, on what happens if the page is modified after UFFDIO_COPY but
before DONTNEED.
UFFDIO_REMAP guarantees full atomicity when moving the page, IOW, threads
can be updating the pages when ioctl(UFFDIO_REMAP), data won't get lost
during movement, and it will generate a missing event after moved, with
latest data showing up on dest.
I'm not sure that means such a fallback is a problem, Suren may know
better with the use case.
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2023-10-02 15:22 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-23 1:31 [PATCH v2 0/3] userfaultfd remap option Suren Baghdasaryan
2023-09-23 1:31 ` [PATCH v2 1/3] userfaultfd: UFFDIO_REMAP: rmap preparation Suren Baghdasaryan
2023-09-28 16:23 ` Peter Xu
2023-09-28 20:03 ` Suren Baghdasaryan
2023-10-02 14:42 ` David Hildenbrand
2023-10-02 15:23 ` Peter Xu
2023-10-02 17:30 ` David Hildenbrand
2023-10-03 17:56 ` Suren Baghdasaryan
2023-09-23 1:31 ` [PATCH v2 2/3] userfaultfd: UFFDIO_REMAP uABI Suren Baghdasaryan
2023-09-27 10:06 ` potential new userfaultfd vs khugepaged conflict [was: Re: [PATCH v2 2/3] userfaultfd: UFFDIO_REMAP uABI] Jann Horn
2023-09-27 17:12 ` Suren Baghdasaryan
2023-09-28 15:29 ` Jann Horn
2023-09-27 12:47 ` [PATCH v2 2/3] userfaultfd: UFFDIO_REMAP uABI Jann Horn
2023-09-27 13:29 ` David Hildenbrand
2023-09-27 18:25 ` Suren Baghdasaryan
2023-09-28 16:28 ` Peter Xu
2023-09-28 17:15 ` David Hildenbrand
2023-09-28 18:32 ` Suren Baghdasaryan
2023-09-28 20:11 ` Suren Baghdasaryan
2023-09-28 19:00 ` Peter Xu
2023-10-02 7:49 ` David Hildenbrand
2023-09-28 16:24 ` Peter Xu
2023-09-28 17:05 ` David Hildenbrand
2023-09-28 17:21 ` Peter Xu
2023-09-28 17:51 ` David Hildenbrand
2023-09-28 18:34 ` Peter Xu
2023-09-28 19:47 ` Suren Baghdasaryan
2023-10-02 8:00 ` David Hildenbrand
2023-10-02 15:21 ` Peter Xu [this message]
2023-10-02 15:46 ` Lokesh Gidra
2023-10-02 15:55 ` Lokesh Gidra
2023-10-02 17:43 ` David Hildenbrand
2023-10-02 19:33 ` Lokesh Gidra
2023-10-03 20:04 ` Suren Baghdasaryan
2023-10-03 20:21 ` Peter Xu
2023-10-03 21:08 ` David Hildenbrand
2023-10-03 21:20 ` Peter Xu
2023-10-03 22:26 ` Suren Baghdasaryan
2023-10-03 23:39 ` Lokesh Gidra
2023-10-06 12:30 ` David Hildenbrand
2023-10-06 15:02 ` Suren Baghdasaryan
2023-10-03 21:04 ` David Hildenbrand
2023-10-02 17:33 ` David Hildenbrand
2023-10-02 17:36 ` David Hildenbrand
2023-09-27 18:07 ` Suren Baghdasaryan
2023-09-27 20:04 ` Jann Horn
2023-09-27 20:42 ` Suren Baghdasaryan
2023-09-27 21:08 ` Suren Baghdasaryan
2023-09-27 22:48 ` Jann Horn
2023-09-28 15:36 ` Suren Baghdasaryan
2023-09-28 17:09 ` Peter Xu
2023-09-28 18:23 ` Suren Baghdasaryan
2023-09-28 18:43 ` Peter Xu
2023-09-28 19:50 ` Suren Baghdasaryan
2023-09-23 1:31 ` [PATCH v2 3/3] selftests/mm: add UFFDIO_REMAP ioctl test Suren Baghdasaryan
-- strict thread matches above, loose matches on Subject: below --
2023-09-23 5:39 [PATCH v2 2/3] userfaultfd: UFFDIO_REMAP uABI kernel test robot
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