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Date:   Fri, 28 Jul 2023 18:13:26 +0200
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Subject: Re: [RFC PATCH v11 10/29] mm: Add AS_UNMOVABLE to mark mapping as
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To:     Vlastimil Babka <vbabka@suse.cz>,
        Matthew Wilcox <willy@infradead.org>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc:     Sean Christopherson <seanjc@google.com>,
        Marc Zyngier <maz@kernel.org>,
        Oliver Upton <oliver.upton@linux.dev>,
        Huacai Chen <chenhuacai@kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Anup Patel <anup@brainfault.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Andrew Morton <akpm@linux-foundation.org>,
        Paul Moore <paul@paul-moore.com>,
        James Morris <jmorris@namei.org>,
        "Serge E. Hallyn" <serge@hallyn.com>, kvm@vger.kernel.org,
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        Chao Peng <chao.p.peng@linux.intel.com>,
        Fuad Tabba <tabba@google.com>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Yu Zhang <yu.c.zhang@linux.intel.com>,
        Vishal Annapurve <vannapurve@google.com>,
        Ackerley Tng <ackerleytng@google.com>,
        Maciej Szmigiero <mail@maciej.szmigiero.name>,
        David Hildenbrand <david@redhat.com>,
        Quentin Perret <qperret@google.com>,
        Michael Roth <michael.roth@amd.com>,
        Wang <wei.w.wang@intel.com>,
        Liam Merwick <liam.merwick@oracle.com>,
        Isaku Yamahata <isaku.yamahata@gmail.com>
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 <692b09f7-70d9-1119-7fe2-3e7396ec259d@suse.cz>
From:   Paolo Bonzini <pbonzini@redhat.com>
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On 7/28/23 18:02, Vlastimil Babka wrote:
>> There's even a comment to that effect later on in the function:
> Hmm, well spotted. But it wouldn't be so great if we now had to lock every
> inspected page (and not just dirty pages), just to check the AS_ bit.
> 
> But I wonder if this is leftover from previous versions. Are the guest pages
> even PageLRU currently? (and should they be, given how they can't be swapped
> out or anything?) If not, isolate_migratepages_block will skip them anyway.

No, they're not (migration or even swap-out is not excluded for the 
future, but for now it's left for future work.

Paolo