Message-ID: <982c1623-ac28-2743-d6a3-4faf42f72d47@redhat.com>
Date:   Thu, 2 Mar 2023 15:01:26 +0100
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Subject: Re: [PATCH v2] mm/uffd: UFFD_FEATURE_WP_UNPOPULATED
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To:     Peter Xu <peterx@redhat.com>
Cc:     Muhammad Usama Anjum <usama.anjum@collabora.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Andrea Arcangeli <aarcange@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Nadav Amit <nadav.amit@gmail.com>,
        "kernel@collabora.com" <kernel@collabora.com>
References: <20230227230044.1596744-1-peterx@redhat.com>
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 <8783f47e-76ea-cd24-e373-f2156884cd05@redhat.com> <ZACrOWKWdVYO/EAI@x1n>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
In-Reply-To: <ZACrOWKWdVYO/EAI@x1n>
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On 02.03.23 14:57, Peter Xu wrote:
> On Thu, Mar 02, 2023 at 10:37:44AM +0100, David Hildenbrand wrote:
>> Especially for such large sparse VMAs, the current way of allocating
>> pagetables to place markers/zeropages is far from optimal.
> 
> IMHO that's not a generic workload.  As mentioned in the reply there, I
> would suggest we go with simple then we have space to optimize it in the
> future if necessary, because the API will be the same.
> 

I disagree with "generic workload", we use sparse mmaps all over the 
place, and when blindly used by e.g., CRIU, we'll simply end up wasting 
memory and time.

But I already agreed that this optimization that is a separate thing to 
implement.

-- 
Thanks,

David / dhildenb