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Tue, 08 Sep 2026 09:29:39 +0000 X-Mizu-Trace-ID: c1b4dc536328070e X-Migadu-Flow: FLOW_OUT Message-ID: Date: Tue, 8 Sep 2026 17:29:34 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 11/11] Documentation/mm: update DAX vmemmap deduplication docs To: Muchun Song , Andrew Morton , David Hildenbrand , Oscar Salvador , Madhavan Srinivasan , Michael Ellerman , Jonathan Corbet Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org, Muchun Song , Lorenzo Stoakes , Mike Rapoport , Nicholas Piggin , Christophe Leroy , Randy Dunlap References: <20260908030335.96549-1-songmuchun@bytedance.com> <20260908030335.96549-12-songmuchun@bytedance.com> From: Qi Zheng In-Reply-To: <20260908030335.96549-12-songmuchun@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 3DB7720003 X-Stat-Signature: hac8wwmuotyey7qsdqqakhhneedehibn X-Rspam-User: X-HE-Tag: 1788859781-983636 X-HE-Meta: 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 oyn8zhQt Tuxf7Xoq+WjQ7Q/BtWvTkyg1ATJVCRP1TOY7JEegjKtpwwCb6SgWKdtHBwXrHTjoG71YFUQlvp41Pl5oAJOtLVWBMeBm2JS8xC8glXVbZBa6q+mgXEqE31fFWo9DBM68pJRIBos1CyHATRxyNP6ZvKzNW6y2WI9UbGu1YE5xSNPXfindN/PEXy3S/SNjUR1MAg+UJ+mGhfp8DMBjVpmNUSSPh0/9ZPIiBpfYqZgId6kyj5h8xqlVYXjA+cmpR7ykrSH5UMEPmihPxiDMxcqTC4nnqDdQ+Gl7FczR9IbU3Y228IKuCg1DH9f8YXsCj0uaiJTEgwuSJ1d1UFag= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/8/26 11:03 AM, Muchun Song wrote: > Device DAX now uses the common per-zone shared tail page for vmemmap > deduplication. The old documentation still described a DAX-specific > layout with a separately populated tail vmemmap page and half the HugeTLB > savings. > > Update the generic and powerpc documentation to describe the shared layout. > In the powerpc document, keep the radix and 64K-specific details, drop the > duplicated 4K PUD arithmetic, and replace the repeated device-dax diagrams > with a single parameterized PMD/PUD diagram. > > Signed-off-by: Muchun Song > --- > v2: > - Clarify the commit message to state that the 4K PUD arithmetic is > intentionally dropped reported by Sashiko. > --- > Documentation/arch/powerpc/vmemmap_dedup.rst | 90 ++++---------------- > Documentation/mm/vmemmap_dedup.rst | 32 +------ > 2 files changed, 21 insertions(+), 101 deletions(-) Acked-by: Qi Zheng Thanks, Qi