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From: David Hildenbrand <david@redhat.com>
To: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>,
	Lokesh Gidra <lokeshgidra@google.com>,
	akpm@linux-foundation.org, viro@zeniv.linux.org.uk,
	brauner@kernel.org, shuah@kernel.org, aarcange@redhat.com,
	hughd@google.com, mhocko@suse.com, axelrasmussen@google.com,
	rppt@kernel.org, willy@infradead.org, Liam.Howlett@oracle.com,
	jannh@google.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 v3 2/3] userfaultfd: UFFDIO_MOVE uABI
Date: Mon, 23 Oct 2023 18:36:16 +0200	[thread overview]
Message-ID: <96899aa6-700b-41b9-ab11-2cae48d75549@redhat.com> (raw)
In-Reply-To: <1156ad46-1952-4892-8092-bfbb8588c3f3@redhat.com>

On 23.10.23 14:03, David Hildenbrand wrote:
> On 22.10.23 17:46, Peter Xu wrote:
>> On Fri, Oct 20, 2023 at 07:16:19PM +0200, David Hildenbrand wrote:
>>> These are rather the vibes I'm getting from Peter. "Why rename it, could
>>> confuse people because the original patches are old", "Why exclude it if it
>>> has been included in the original patches". Not the kind of reasoning I can
>>> relate to when it comes to upstreaming some patches.
>>
>> You can't blame anyone if you misunderstood and biased the question.
>>
>> The first question is definitely valid, even until now.  You guys still
>> prefer to rename it, which I'm totally fine with.
>>
>> The 2nd question is wrong from your interpretation.  That's not my point,
>> at least not starting from a few replies already.  What I was asking for is
>> why such page movement between mm is dangerous.  I don't think I get solid
>> answers even until now.
>>
>> Noticing "memcg is missing" is not an argument for "cross-mm is dangerous",
>> it's a review comment.  Suren can address that.
>>
>> You'll propose a new feature that may tag an mm is not an argument either,
>> if it's not merged yet.  We can also address that depending on what it is,
>> also on which lands earlier.
>>
>> It'll be good to discuss these details even in a single-mm support.  Anyone
>> would like to add that can already refer to discussion in this thread.
>>
>> I hope I'm clear.
>>
> 
> I said everything I had to say, go read what I wrote.

Re-read your message after flying over first couple of paragraphs 
previously a bit quick too quickly (can easily happen when I'm told that 
I misunderstand questions and read them in a "biased" way).

I'll happy to discuss cross-mm support once we actually need it. I just 
don't see the need to spend any energy on that right now, without any 
users on the horizon.

[(a) I didn't blame anybody, I said that I don't understand the 
reasoning. (b) I hope I made it clear that this is added complexity (and 
not just currently dangerous) and so far I haven't heard a compelling 
argument why we should do any of that or even spend our time discussing 
that. (c) I never used "memcg is missing" as an argument for "cross-mm 
is dangerous", all about added complexity without actual users. (d) "it 
easily shows that there are cases  where this will require extra work -- 
without any current benefits" -- is IMHO a perfectly fine argument 
against complexity that currently nobody needs]

-- 
Cheers,

David / dhildenb



  reply	other threads:[~2023-10-23 16:36 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-09  6:42 [PATCH v3 0/3] userfaultfd move option Suren Baghdasaryan
2023-10-09  6:42 ` [PATCH v3 1/3] mm/rmap: support move to different root anon_vma in folio_move_anon_rmap() Suren Baghdasaryan
2023-10-12 22:01   ` Peter Xu
2023-10-13  8:04     ` David Hildenbrand
2023-10-19 15:19       ` Suren Baghdasaryan
2023-10-09  6:42 ` [PATCH v3 2/3] userfaultfd: UFFDIO_MOVE uABI Suren Baghdasaryan
2023-10-09 14:38   ` David Hildenbrand
2023-10-09 16:21     ` Suren Baghdasaryan
2023-10-09 16:23       ` David Hildenbrand
2023-10-09 16:29         ` Lokesh Gidra
2023-10-09 17:56           ` Lokesh Gidra
2023-10-10  1:49             ` Suren Baghdasaryan
2023-10-12 20:11           ` Peter Xu
2023-10-13  9:56             ` David Hildenbrand
2023-10-13 16:08               ` Peter Xu
2023-10-13 16:49                 ` Lokesh Gidra
2023-10-13 17:05                   ` Peter Xu
2023-10-16 18:01                 ` David Hildenbrand
2023-10-16 19:01                   ` Peter Xu
2023-10-17 15:55                     ` David Hildenbrand
2023-10-17 18:59                       ` Peter Xu
2023-10-19 15:41                         ` David Hildenbrand
2023-10-19 19:53                           ` Peter Xu
2023-10-19 20:02                             ` Suren Baghdasaryan
2023-10-19 20:43                               ` Peter Xu
2023-10-20 10:02                             ` David Hildenbrand
2023-10-20 14:09                               ` Suren Baghdasaryan
2023-10-20 17:16                                 ` David Hildenbrand
2023-10-22 15:46                                   ` Peter Xu
2023-10-23 12:03                                     ` David Hildenbrand
2023-10-23 16:36                                       ` David Hildenbrand [this message]
2023-10-23 17:33                                         ` Suren Baghdasaryan
2023-10-19 21:45                 ` Suren Baghdasaryan
2023-10-12 21:59   ` Peter Xu
2023-10-19 21:24     ` Suren Baghdasaryan
2023-10-22 17:01       ` Peter Xu
2023-10-23 17:43         ` Suren Baghdasaryan
2023-10-23 18:37           ` Peter Xu
2023-10-23 19:01             ` Suren Baghdasaryan
2023-10-17 19:39   ` kernel test robot
2023-10-19 21:55     ` Suren Baghdasaryan
2023-10-23 12:29   ` David Hildenbrand
2023-10-23 15:53     ` David Hildenbrand
2023-10-23 19:00       ` Suren Baghdasaryan
2023-10-23 18:56     ` Suren Baghdasaryan
2023-10-24 14:27       ` David Hildenbrand
2023-10-24 14:36         ` Suren Baghdasaryan
2023-10-09  6:42 ` [PATCH v3 3/3] selftests/mm: add UFFDIO_MOVE ioctl test Suren Baghdasaryan
2023-10-12 22:29   ` Peter Xu
2023-10-19 15:43     ` Suren Baghdasaryan
2023-10-19 17:29       ` Axel Rasmussen
2023-10-19 19:33         ` Peter Xu

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