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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rkp9S-00000008LXl-2Wr4; Thu, 14 Mar 2024 17:45:58 +0000 Date: Thu, 14 Mar 2024 17:45:58 +0000 From: Matthew Wilcox To: John Hubbard Cc: David Hildenbrand , Jane Chu , linux-mm@kvack.org Subject: Re: updated documentation: Splitting pinned folios Message-ID: References: <57c9e228-9aca-4da6-a714-f175f053ff50@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: DE079180025 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: su6d5jdhfhhf8tonajeyi7bki5spegr9 X-HE-Tag: 1710438361-166483 X-HE-Meta: U2FsdGVkX1//LavbcPvnm9tS7EaK88tzdyasTyX05DPCjOt7bUWcjNLUbdlinrr6KYod3OkspThLJcxBOIHwoa3wdvEkhIMboFXEpGiB6wAnE2JlFi/vFhMVBKH/X9OZKIkOewfO2cVyzcn4E5W7luxrrFfvLPLR27l/hXZvqfmBnGQxw7P7KHXrIye4JLFfK/MDgkx+Y4UkHXwaXk9B2StAE9pZ3ViG0/JYwVUZkMKpw2F3ipe1LXZS/sDztm4fSS8FRMjjzu8u11Zcn3dbO4LXPAtEibsWP4+YsuSuJpJP4yXf7Y5grk+n08931UPyZxkKYTca2uoXMjF1ewQ4uTl7jwl6dUqMlGJCcnNN+jzB3AYiI6QmSsFnh8N7R5Rmq59thGPZj3iWRoagF8cH6/tqTTPBzOKJrDx++Zaw07clCT9eiXz750hNoZYoSRqsfyFJEtmp+wEjYIFazedJ8wvTlUWtlGHrhNSO2ETU8qNeLC1VxglwGSvY1uRhRx0sp6m8EvyQ2N1dg8yUOoYeSBJxagoZhkqVRKUYDg45yH5WSP0htyL2reQjbBo3aVoIo95/CiJSPpvzSkTNlfQKhf2CjkHsNYqgdPwo8UdXW7ApDNOZNzTXV4FqK2GxyluMsG37p/MUlvBHuC8GoU8uVqTlySAPn9weN2mPlmvBf/wnYfoCIVoB/jl+Avn5c/38wBLd9jAxxyoDN5uLvl9udmIjqwJMlJ6QliajR9sWHdu/sQ8Cwa690MzU/eej1Ehmv/BsIzxzAjBCOjpFAj2DmX8jp8TkSuPDCXgemmqKzCCd3y9IzG3TkQrYi+nveY7QB3xpr418FS/5teGrlQyh2A== 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 Wed, Mar 13, 2024 at 07:46:54PM -0700, John Hubbard wrote: > /* > * This function splits a huge page into normal pages. @page can point to any s/huge page/large folio/ and s/normal/smaller/ ? > * subpage of the huge page to split. The split operation does not change the Trying to get away from "subpage", maybe "can point to any page within the folio"? I think following these suggestions throughout the text below will make it clearer ... > * position of @page. > * > * Prerequisites: > * > * 1) The caller must hold a reference on the @page's owning folio, also known as > * the huge page. > * > * 2) The huge page must be locked. > * > * 3) The folio must not be pinned. Pinned folios will not be split; instead, > * the caller will receive an -EBUSY. > * > * After splitting, the folio's refcount is transfered to @page (not the head > * page, unless @page is actually the head page). The other subpages may be > * freed if they are not mapped. > * > * If @list is null, tail pages will be added to LRU list, otherwise, to @list. > * > * Both head page and tail pages will inherit mapping, flags, and so on from the > * hugepage. > * > * Returns 0 if the hugepage was split successfully. > * > * Returns -EBUSY if @page's folio is pinned, or if the anon_vma disappeared > * from under us. > */ > int split_huge_page_to_list(struct page *page, struct list_head *list) > > thanks, > -- > John Hubbard > NVIDIA >