From: David Hildenbrand <david@redhat.com>
To: Peter Xu <peterx@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: Thu, 28 Sep 2023 19:05:40 +0200 [thread overview]
Message-ID: <98b21e78-a90d-8b54-3659-e9b890be094f@redhat.com> (raw)
In-Reply-To: <ZRWo1daWBnwNz0/O@x1n>
On 28.09.23 18:24, Peter Xu wrote:
> On Wed, Sep 27, 2023 at 03:29:35PM +0200, David Hildenbrand wrote:
>>>> + if (!pte_same(*src_pte, orig_src_pte) ||
>>>> + !pte_same(*dst_pte, orig_dst_pte) ||
>>>> + folio_test_large(src_folio) ||
>>>> + folio_estimated_sharers(src_folio) != 1) {
>>
>> ^ here you should check PageAnonExclusive. Please get rid of any implicit
>> explicit/implcit mapcount checks.
>
> David, is PageAnon 100% accurate now in the current tree?
>
> IOW, can it be possible that the page has total_mapcount==1 but missing
> AnonExclusive bit in any possible way?
As described as reply to v1, without fork() and KSM, the PAE bit should
stick around. If that's not the case, we should investigate why.
If we ever support the post-fork case (which the comment above
remap_pages() excludes) we'll need good motivation why we'd want to make
this overly-complicated feature even more complicated.
--
Cheers,
David / dhildenb
next prev parent reply other threads:[~2023-09-28 17:06 UTC|newest]
Thread overview: 55+ 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 [this message]
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
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
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