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[2003:d8:2f2d:2400:4052:3b5:fff9:4ed0]) by smtp.gmail.com with UTF8SMTPSA id 5b1f17b1804b1-4535e97aa15sm3975415e9.2.2025.06.18.10.40.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 18 Jun 2025 10:40:45 -0700 (PDT) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linux-doc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, virtualization@lists.linux.dev, linux-fsdevel@vger.kernel.org, David Hildenbrand , Andrew Morton , Jonathan Corbet , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Jerrin Shaji George , Arnd Bergmann , Greg Kroah-Hartman , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , Alexander Viro , Christian Brauner , Jan Kara , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , "Matthew Wilcox (Oracle)" , Minchan Kim , Sergey Senozhatsky , Brendan Jackman , Johannes Weiner , Jason Gunthorpe , John Hubbard , Peter Xu , Xu Xin , Chengming Zhou , Miaohe Lin , Naoya Horiguchi , Oscar Salvador , Rik van Riel , Harry Yoo , Qi Zheng , Shakeel Butt Subject: [PATCH RFC 11/29] mm/migrate: move movable_ops page handling out of move_to_new_folio() Date: Wed, 18 Jun 2025 19:39:54 +0200 Message-ID: <20250618174014.1168640-12-david@redhat.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250618174014.1168640-1-david@redhat.com> References: <20250618174014.1168640-1-david@redhat.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: F1qId1CTqzDd2XrfSEd3yi6IIqrqvF3pMfPAHalomHs_1750268447 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true Let's move that handling directly into migrate_folio_move(), so we can simplify move_to_new_folio(). While at it, fixup the documentation a bit. Note that unmap_and_move_huge_page() does not care, because it only deals with actual folios. (we only support migration of individual movable_ops pages) Signed-off-by: David Hildenbrand --- mm/migrate.c | 61 ++++++++++++++++++++++++---------------------------- 1 file changed, 28 insertions(+), 33 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index 456e41dad83a2..db807f9bbf975 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1024,11 +1024,12 @@ static int fallback_migrate_folio(struct address_space *mapping, } /* - * Move a page to a newly allocated page - * The page is locked and all ptes have been successfully removed. + * Move a src folio to a newly allocated dst folio. * - * The new page will have replaced the old page if this function - * is successful. + * The src and dst folios are locked and the src folios was unmapped from + * the page tables. + * + * On success, the src folio was replaced by the dst folio. * * Return value: * < 0 - error code @@ -1037,34 +1038,30 @@ static int fallback_migrate_folio(struct address_space *mapping, static int move_to_new_folio(struct folio *dst, struct folio *src, enum migrate_mode mode) { + struct address_space *mapping = folio_mapping(src); int rc = -EAGAIN; - bool is_lru = !__folio_test_movable(src); VM_BUG_ON_FOLIO(!folio_test_locked(src), src); VM_BUG_ON_FOLIO(!folio_test_locked(dst), dst); - if (likely(is_lru)) { - struct address_space *mapping = folio_mapping(src); - - if (!mapping) - rc = migrate_folio(mapping, dst, src, mode); - else if (mapping_inaccessible(mapping)) - rc = -EOPNOTSUPP; - else if (mapping->a_ops->migrate_folio) - /* - * Most folios have a mapping and most filesystems - * provide a migrate_folio callback. Anonymous folios - * are part of swap space which also has its own - * migrate_folio callback. This is the most common path - * for page migration. - */ - rc = mapping->a_ops->migrate_folio(mapping, dst, src, - mode); - else - rc = fallback_migrate_folio(mapping, dst, src, mode); + if (!mapping) + rc = migrate_folio(mapping, dst, src, mode); + else if (mapping_inaccessible(mapping)) + rc = -EOPNOTSUPP; + else if (mapping->a_ops->migrate_folio) + /* + * Most folios have a mapping and most filesystems + * provide a migrate_folio callback. Anonymous folios + * are part of swap space which also has its own + * migrate_folio callback. This is the most common path + * for page migration. + */ + rc = mapping->a_ops->migrate_folio(mapping, dst, src, + mode); + else + rc = fallback_migrate_folio(mapping, dst, src, mode); - if (rc != MIGRATEPAGE_SUCCESS) - goto out; + if (rc == MIGRATEPAGE_SUCCESS) { /* * For pagecache folios, src->mapping must be cleared before src * is freed. Anonymous folios must stay anonymous until freed. @@ -1074,10 +1071,7 @@ static int move_to_new_folio(struct folio *dst, struct folio *src, if (likely(!folio_is_zone_device(dst))) flush_dcache_folio(dst); - } else { - rc = migrate_movable_ops_page(&dst->page, &src->page, mode); } -out: return rc; } @@ -1328,20 +1322,21 @@ static int migrate_folio_move(free_folio_t put_new_folio, unsigned long private, int rc; int old_page_state = 0; struct anon_vma *anon_vma = NULL; - bool is_lru = !__folio_test_movable(src); struct list_head *prev; __migrate_folio_extract(dst, &old_page_state, &anon_vma); prev = dst->lru.prev; list_del(&dst->lru); + if (unlikely(__folio_test_movable(src))) { + rc = migrate_movable_ops_page(&dst->page, &src->page, mode); + goto out_unlock_both; + } + rc = move_to_new_folio(dst, src, mode); if (rc) goto out; - if (unlikely(!is_lru)) - goto out_unlock_both; - /* * When successful, push dst to LRU immediately: so that if it * turns out to be an mlocked page, remove_migration_ptes() will -- 2.49.0