linux-kernel - Re: [PATCH 00/11] mm/mremap: introduce more mergeable mremap via MREMAP_RELOCATE

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Message-ID: <58560256-58da-4fa6-a953-d2c4695ffba8@lucifer.local>
Date: Tue, 17 Jun 2025 11:57:11 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: David Hildenbrand <david@...hat.com>
Cc: Pedro Falcato <pfalcato@...e.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
        "Liam R . Howlett" <Liam.Howlett@...cle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Matthew Wilcox <willy@...radead.org>, Rik van Riel <riel@...riel.com>,
        Harry Yoo <harry.yoo@...cle.com>, Zi Yan <ziy@...dia.com>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        Nico Pache <npache@...hat.com>, Ryan Roberts <ryan.roberts@....com>,
        Dev Jain <dev.jain@....com>, Jakub Matena <matenajakub@...il.com>,
        Wei Yang <richard.weiyang@...il.com>, Barry Song <baohua@...nel.org>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 00/11] mm/mremap: introduce more mergeable mremap via
 MREMAP_RELOCATE_ANON

On Tue, Jun 17, 2025 at 10:45:53AM +0200, David Hildenbrand wrote:
> mremap() is already an expensive operation ... so I think we need a pretty
> convincing case to make this configurable by the user at all for each
> individual mremap() invocation.

My measurements suggest, unless you hit a very unfortunate case of -huge
faulted in range all mapped PTE- that the work involved is not all that
much more substantial in terms of order of magnitude than a normal mremap()
operation.

>
> --
> Cheers,
>
> David / dhildenb
>