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Wed, 15 Oct 2025 18:26:05 -0700 (PDT) From: wang lian To: richard.weiyang@gmail.com Cc: Liam.Howlett@oracle.com, akpm@linux-foundation.org, baohua@kernel.org, baolin.wang@linux.alibaba.com, david@redhat.com, dev.jain@arm.com, lance.yang@linux.dev, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, npache@redhat.com, ryan.roberts@arm.com, ziy@nvidia.com, wang lian Subject: Re: [Patch v2 2/2] mm/huge_memory: Optimize and simplify __split_unmapped_folio() logic Date: Thu, 16 Oct 2025 09:25:47 +0800 Message-ID: <20251016012547.39871-1-lianux.mm@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20251016004613.514-3-richard.weiyang@gmail.com> References: <20251016004613.514-3-richard.weiyang@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: u3pda1z3fkp394dosfeqk37f8if9hser X-Rspamd-Queue-Id: EDA0F2000F X-Rspamd-Server: rspam06 X-Rspam-User: X-HE-Tag: 1760577966-165704 X-HE-Meta: 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 VgiZr2YE 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > Existing __split_unmapped_folio() code splits the given folio and update > stats, but it is complicated to understand. > After simplification, __split_unmapped_folio() directly calculate and > update the folio statistics upon a successful split: > * All resulting folios are @split_order. > * The number of new folios are calculated directly from @old_order and @split_order. > * The folio for the next split is identified as the one containing @split_at. > * An xas_try_split() error is returned directly without worrying about stats updates. > Signed-off-by: Wei Yang > Cc: Zi Yan > Reviewed-by: Zi Yan The simplification looks great and makes the logic much easier to follow. The new comment you added is also very helpful for understanding the difference between the two split modes. LGTM. Reviewed-by: wang lian > + * For uniform split, we have finished the job. > + * For non-uniform split, we assign folio to the one the one > + * containing @split_at and assign @old_order to @split_order. -- Best Regards, wang lian