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AJvYcCUbl07PRY2L8DtDzayn0NRHJDba6rZH6WuqZmZALx146YJ60zaHb1rkch2kBH8atPcCI0XIv1xVx1dr9Ac=@vger.kernel.org X-Gm-Message-State: AOJu0YzyOVTQY8Ch+k7xBPUzFXhGrZCfBZkgd7jflPH3MPRNLnfQ3e2S DuXK3rsLXQoeD+KvJ9dMNo9jBkp7jD39+Sn6NrEkNp6IWTo2PmXdsM3BVwvelpTOswZGKThgEEl HiajNAg== X-Received: from pjbnc12.prod.google.com ([2002:a17:90b:37cc:b0:34c:d212:cb7f]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:570f:b0:32e:72bd:6d5a with SMTP id 98e67ed59e1d1-35272bcba8cmr975439a91.1.1768517400490; Thu, 15 Jan 2026 14:50:00 -0800 (PST) Date: Thu, 15 Jan 2026 14:49:59 -0800 In-Reply-To: <20260106102024.25023-1-yan.y.zhao@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260106101646.24809-1-yan.y.zhao@intel.com> <20260106102024.25023-1-yan.y.zhao@intel.com> Message-ID: Subject: Re: [PATCH v3 06/24] KVM: x86/mmu: Disallow page merging (huge page adjustment) for mirror root From: Sean Christopherson To: Yan Zhao Cc: pbonzini@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org, rick.p.edgecombe@intel.com, dave.hansen@intel.com, kas@kernel.org, tabba@google.com, ackerleytng@google.com, michael.roth@amd.com, david@kernel.org, vannapurve@google.com, sagis@google.com, vbabka@suse.cz, thomas.lendacky@amd.com, nik.borisov@suse.com, pgonda@google.com, fan.du@intel.com, jun.miao@intel.com, francescolavra.fl@gmail.com, jgross@suse.com, ira.weiny@intel.com, isaku.yamahata@intel.com, xiaoyao.li@intel.com, kai.huang@intel.com, binbin.wu@linux.intel.com, chao.p.peng@intel.com, chao.gao@intel.com Content-Type: text/plain; charset="us-ascii" On Tue, Jan 06, 2026, Yan Zhao wrote: > From: Rick P Edgecombe > > Disallow page merging (huge page adjustment) for the mirror root by > utilizing disallowed_hugepage_adjust(). Why? What is this actually doing? The below explains "how" but I'm baffled as to the purpose. I'm guessing there are hints in the surrounding patches, but I haven't read them in depth, and shouldn't need to in order to understand the primary reason behind a change.