From: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
To: Brian Geffon <bgeffon@google.com>
Cc: mtk.manpages@gmail.com, linux-man@vger.kernel.org,
Sonny Rao <sonnyrao@google.com>,
Jesse Barnes <jsbarnes@google.com>,
Vlastimil Babka <vbabka@suse.cz>,
Minchan Kim <minchan@kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Lokesh Gidra <lokeshgidra@google.com>
Subject: Re: [PATCH v2] mremap.2: Add information for MREMAP_DONTUNMAP.
Date: Wed, 22 Apr 2020 14:05:41 +0200 [thread overview]
Message-ID: <80e408d3-f46c-58ef-0539-fd0e5778fef3@gmail.com> (raw)
In-Reply-To: <CADyq12xA69pSZ=JfMuG_c8T1UHepmdSqBwLLPgFrOyXeveVk4w@mail.gmail.com>
On 4/17/20 5:01 AM, Brian Geffon wrote:
> Hi Michael,
>
>> Thanks for this patch. I've applied it, and done quite a
>> bit of editing. Could you please take a look at the
>> version in Git, and let me know if I made any bad changes
>> to your text.
>
> Your changes look good.
>
>> You write "move", but would it not be more correcrt to say something
>> like "duplicate"?
>
> It's a little of both, it duplicates the VMA but moves the page table
> entries. So the behavior feels more like a move followed by a new
> mapping created that had the same properties as the previous. Does
> that make sense?
>
>>> +Possible applications for this behavior might be garbage collection or
>>
>> Can you elaborate the garbage collection use case a little, please?
>
> Lokesh, who is CCed, can probably expand better than I can, Lokesh
> would you mind elaborating on how the JVM plans to use this.
>
>>> +non-cooperative
>>> +.BR userfaultfd (2) .
>>
>> What is noncooperative userfaultfd(2)?
>
> No cooperative userfaultfd is the term that people tend to use when
> the threads accessing the memory are not cooperating with the fault
> handling, MREMAP_DONTUNMAP is interesting for this as you can yank out
> the page tables from a running process and immediately start handling
> faults for the registered range without having to stop the process.
>
> I hope that answers your questions, feel free to ask if you need more
> clarification.
Thanks, Brian. See my reply to Loresh in just a moment
Cheers,
Mcihael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
prev parent reply other threads:[~2020-04-22 12:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-15 16:49 [PATCH v2] mremap.2: Add information for MREMAP_DONTUNMAP Brian Geffon
2020-04-16 7:07 ` Michael Kerrisk (man-pages)
2020-04-17 3:01 ` Brian Geffon
2020-04-22 0:15 ` Lokesh Gidra
2020-04-22 12:08 ` Michael Kerrisk (man-pages)
2020-04-22 12:05 ` Michael Kerrisk (man-pages) [this message]
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