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Shutemov" , David Hildenbrand , Yang Shi , Miaohe Lin , Kefeng Wang , Yu Zhao , John Hubbard , Baolin Wang , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Kairui Song Subject: Re: [PATCH v10 2/8] mm/huge_memory: add two new (not yet used) functions for folio_split() Message-ID: References: <20250307174001.242794-1-ziy@nvidia.com> <20250307174001.242794-3-ziy@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250307174001.242794-3-ziy@nvidia.com> X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 11957A0009 X-Stat-Signature: 6d84xjjmiema1r7eshf7kbfoxj5q7p4z X-Rspam-User: X-HE-Tag: 1741624326-987230 X-HE-Meta: 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 A9K1gNyJ uq1PIjj7mV8v+kVRKAWYTYJMy+ggl89cY0RQNzrlvCkjsWeqUCO4nDmH96BrQIU/yMFlyVYTpuENlIgQDX/J9Mo88RyRkJ2W9N3RPWNHR0it2Rl+jMQlof3s41U6hKvZ4fiVmyuKUR7BFpTXZjZAe9mAc7ycJq9YQnDm2UsjMRWkRrKZIFjuX5oL3YUCwLMONJcZJH7w1Fgx2rwjXvmmY6stFt+46AdZQbTlLJ8wKuRGvr1WOuZpceN+Ua/jh11sVhMgwVa/xexXqZ0BC48eNGFxSDQ== 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: On Fri, Mar 07, 2025 at 12:39:55PM -0500, Zi Yan wrote: > + for (index = new_nr_pages; index < nr_pages; index += new_nr_pages) { > + struct page *head = &folio->page; > + struct page *new_head = head + index; > + > + /* > + * Careful: new_folio is not a "real" folio before we cleared PageTail. > + * Don't pass it around before clear_compound_head(). > + */ > + struct folio *new_folio = (struct folio *)new_head; [...] > + /* ->mapping in first and second tail page is replaced by other uses */ > + VM_BUG_ON_PAGE(new_nr_pages > 2 && new_head->mapping != TAIL_MAPPING, > + new_head); > + new_head->mapping = head->mapping; > + new_head->index = head->index + index; Why are you using new_head->mapping and ->index instead of new_folio?