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Fri, 3 Oct 2025 11:36:31 +0100 Date: Fri, 3 Oct 2025 11:36:29 +0100 From: Jonathan Cameron To: Bharata B Rao CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [RFC PATCH v2 2/8] migrate: implement migrate_misplaced_folios_batch Message-ID: <20251003113629.00004fcb@huawei.com> In-Reply-To: <20250910144653.212066-3-bharata@amd.com> References: <20250910144653.212066-1-bharata@amd.com> <20250910144653.212066-3-bharata@amd.com> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.42; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.203.177.15] X-ClientProxiedBy: lhrpeml100011.china.huawei.com (7.191.174.247) To dubpeml100005.china.huawei.com (7.214.146.113) X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 4CAA0C000A X-Stat-Signature: 5a5tssufddciztcyb4nb9zcezbzufr7e X-Rspam-User: X-HE-Tag: 1759487796-582472 X-HE-Meta: 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 p3sov0WZ XRXiS/au5fakgkGmcT6qowKhORVec89Iqr15s3K2aPFYX9SLu5QfclpifX2Saw/fMfqoyw00e6jS6TBCIpl8sDAnumayifeQME0NiUbl517roQos6G52XSGjsAnKqCyNoiq4JWlA0BocX82XxBq+enjHfSjjG6/dV4v4f6Qmcjeo9+C9Ho6Oab1V5nz5Qo4s7lZRNcOM1YtKc8dr40hqh9OA0mfUW6DRc1R7VqXbiALQExc35bR7S03rMmOj7OCRvVoWatRa31CUKdlulbL7ER8vVfS0ypADvSSQQbgYkQorRTw7nyi4Y0BFm58ChrpxHiVusZtsktfmTVY60tHUeH0NHWriLv+riP0/nr/grLRUbhAKRmd0ZXpFsKuc4nWX0Gk5W0eggJz9grqUA4QO2e89OrfLUorTT+KLJ/M0qLdSdMDPTnetBGG6ICI/KWaoIsiQ6+43TpPNWQ9A= 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, 10 Sep 2025 20:16:47 +0530 Bharata B Rao wrote: > From: Gregory Price > > A common operation in tiering is to migrate multiple pages at once. > The migrate_misplaced_folio function requires one call for each > individual folio. Expose a batch-variant of the same call for use > when doing batch migrations. > I probably missed an earlier discussion of this but what does the _batch postfix add over the plural (folios)? > Signed-off-by: Gregory Price > Signed-off-by: Bharata B Rao > --- > include/linux/migrate.h | 6 ++++++ > mm/migrate.c | 31 +++++++++++++++++++++++++++++++ > 2 files changed, 37 insertions(+) > > diff --git a/include/linux/migrate.h b/include/linux/migrate.h > index acadd41e0b5c..0593f5869be8 100644 > --- a/include/linux/migrate.h > +++ b/include/linux/migrate.h > @@ -107,6 +107,7 @@ static inline int migrate_huge_page_move_mapping(struct address_space *mapping, > int migrate_misplaced_folio_prepare(struct folio *folio, > struct vm_area_struct *vma, int node); > int migrate_misplaced_folio(struct folio *folio, int node); > +int migrate_misplaced_folios_batch(struct list_head *foliolist, int node); > #else > static inline int migrate_misplaced_folio_prepare(struct folio *folio, > struct vm_area_struct *vma, int node) > @@ -117,6 +118,11 @@ static inline int migrate_misplaced_folio(struct folio *folio, int node) > { > return -EAGAIN; /* can't migrate now */ > } > +static inline int migrate_misplaced_folios_batch(struct list_head *foliolist, > + int node) > +{ > + return -EAGAIN; /* can't migrate now */ > +} > #endif /* CONFIG_NUMA_BALANCING */ > > #ifdef CONFIG_MIGRATION > diff --git a/mm/migrate.c b/mm/migrate.c > index 7e356c0b1b5a..1268a95eda0e 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -2714,5 +2714,36 @@ int migrate_misplaced_folio(struct folio *folio, int node) > BUG_ON(!list_empty(&migratepages)); > return nr_remaining ? -EAGAIN : 0; > } > + > +/* Kernel-doc perhaps appropriate? > + * Batch variant of migrate_misplaced_folio. Attempts to migrate > + * a folio list to the specified destination. > + * > + * Caller is expected to have isolated the folios by calling > + * migrate_misplaced_folio_prepare(), which will result in an > + * elevated reference count on the folio. > + * > + * This function will un-isolate the folios, dereference them, and > + * remove them from the list before returning. > + */ > +int migrate_misplaced_folios_batch(struct list_head *folio_list, int node) > +{ > + pg_data_t *pgdat = NODE_DATA(node); > + unsigned int nr_succeeded; > + int nr_remaining; > + > + nr_remaining = migrate_pages(folio_list, alloc_misplaced_dst_folio, > + NULL, node, MIGRATE_ASYNC, > + MR_NUMA_MISPLACED, &nr_succeeded); > + if (nr_remaining) > + putback_movable_pages(folio_list); > + > + if (nr_succeeded) { > + count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded); > + mod_node_page_state(pgdat, PGPROMOTE_SUCCESS, nr_succeeded); > + } > + BUG_ON(!list_empty(folio_list)); > + return nr_remaining ? -EAGAIN : 0; > +} > #endif /* CONFIG_NUMA_BALANCING */ > #endif /* CONFIG_NUMA */