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Mon, 3 Jun 2024 18:46:00 +0800 (CST) Received: from localhost.localdomain (10.175.112.125) by dggpemm100001.china.huawei.com (7.185.36.93) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Mon, 3 Jun 2024 18:46:00 +0800 From: Kefeng Wang To: , CC: Tony Luck , Miaohe Lin , , Matthew Wilcox , David Hildenbrand , Muchun Song , Benjamin LaHaise , , Jiaqi Yan , Hugh Dickins , Vishal Moola , Alistair Popple , Jane Chu , Oscar Salvador , Lance Yang , Kefeng Wang Subject: [PATCH v4 3/6] mm: migrate: split folio_migrate_mapping() Date: Mon, 3 Jun 2024 17:24:36 +0800 Message-ID: <20240603092439.3360652-4-wangkefeng.wang@huawei.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20240603092439.3360652-1-wangkefeng.wang@huawei.com> References: <20240603092439.3360652-1-wangkefeng.wang@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.112.125] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm100001.china.huawei.com (7.185.36.93) X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 12AA61C0014 X-Stat-Signature: nktbt984ah65kzfyyz8k4f5giyngsz3i X-HE-Tag: 1717411565-83264 X-HE-Meta: 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 4IM5K1jK O3+KyWRvEsn7b5CIolnCPya1GSa/24yZAGLGNXqxA1e8Bf5A8sO4IAI+38rWkr+iFnm4IOdt5akMubSMOBoSY79yueowPJV30PKjXDP7VwBLzkG8ijAVZtcDdjNG1EE2yj94QnxzOSiN4AeP8k2iHuipBlDW4w+hTGw252vFJvporVpNzlH6JHeAb3QRClIydJKBbKCmiKDMdcbC5g/22bEdtVFF7eApZ5quUawgPNzZF8STukv9T+jyU8QedO2ACswBBgwxTAQmB3v0= 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: The folio refcount check for !mapping and folio_ref_freeze() for mapping are moved out of the original folio_migrate_mapping(), and there is no turning back for the new __folio_migrate_mapping(), also update comment from page to folio. Note, the folio_ref_freeze() is moved out of xas_lock_irq(), Since the folio is already isolated and locked during migration, so suppose that there is no functional change. Signed-off-by: Kefeng Wang Reviewed-by: Jane Chu --- mm/migrate.c | 63 ++++++++++++++++++++++++++-------------------------- 1 file changed, 32 insertions(+), 31 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index e04b451c4289..e930376c261a 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -393,50 +393,36 @@ static int folio_expected_refs(struct address_space *mapping, } /* - * Replace the page in the mapping. + * Replace the folio in the mapping. * * The number of remaining references must be: - * 1 for anonymous pages without a mapping - * 2 for pages with a mapping - * 3 for pages with a mapping and PagePrivate/PagePrivate2 set. + * 1 for anonymous folios without a mapping + * 2 for folios with a mapping + * 3 for folios with a mapping and PagePrivate/PagePrivate2 set. */ -int folio_migrate_mapping(struct address_space *mapping, - struct folio *newfolio, struct folio *folio, int extra_count) +static void __folio_migrate_mapping(struct address_space *mapping, + struct folio *newfolio, struct folio *folio, int expected_cnt) { XA_STATE(xas, &mapping->i_pages, folio_index(folio)); struct zone *oldzone, *newzone; - int dirty; - int expected_count = folio_expected_refs(mapping, folio) + extra_count; long nr = folio_nr_pages(folio); long entries, i; + int dirty; if (!mapping) { - /* Anonymous page without mapping */ - if (folio_ref_count(folio) != expected_count) - return -EAGAIN; - - /* No turning back from here */ + /* Anonymous folio without mapping */ newfolio->index = folio->index; newfolio->mapping = folio->mapping; if (folio_test_swapbacked(folio)) __folio_set_swapbacked(newfolio); - - return MIGRATEPAGE_SUCCESS; + return; } oldzone = folio_zone(folio); newzone = folio_zone(newfolio); xas_lock_irq(&xas); - if (!folio_ref_freeze(folio, expected_count)) { - xas_unlock_irq(&xas); - return -EAGAIN; - } - - /* - * Now we know that no one else is looking at the folio: - * no turning back from here. - */ + /* Now we know that no one else is looking at the folio */ newfolio->index = folio->index; newfolio->mapping = folio->mapping; folio_ref_add(newfolio, nr); /* add cache reference */ @@ -452,7 +438,7 @@ int folio_migrate_mapping(struct address_space *mapping, entries = 1; } - /* Move dirty while page refs frozen and newpage not yet exposed */ + /* Move dirty while folio refs frozen and newfolio not yet exposed */ dirty = folio_test_dirty(folio); if (dirty) { folio_clear_dirty(folio); @@ -466,22 +452,22 @@ int folio_migrate_mapping(struct address_space *mapping, } /* - * Drop cache reference from old page by unfreezing - * to one less reference. + * Since old folio's refcount freezed, now drop cache reference from + * old folio by unfreezing to one less reference. * We know this isn't the last reference. */ - folio_ref_unfreeze(folio, expected_count - nr); + folio_ref_unfreeze(folio, expected_cnt - nr); xas_unlock(&xas); /* Leave irq disabled to prevent preemption while updating stats */ /* * If moved to a different zone then also account - * the page for that zone. Other VM counters will be + * the folio for that zone. Other VM counters will be * taken care of when we establish references to the - * new page and drop references to the old page. + * new folio and drop references to the old folio. * - * Note that anonymous pages are accounted for + * Note that anonymous folios are accounted for * via NR_FILE_PAGES and NR_ANON_MAPPED if they * are mapped to swap space. */ @@ -518,7 +504,22 @@ int folio_migrate_mapping(struct address_space *mapping, } } local_irq_enable(); +} + +int folio_migrate_mapping(struct address_space *mapping, struct folio *newfolio, + struct folio *folio, int extra_count) +{ + int expected_cnt = folio_expected_refs(mapping, folio) + extra_count; + + if (!mapping) { + if (folio_ref_count(folio) != expected_cnt) + return -EAGAIN; + } else { + if (!folio_ref_freeze(folio, expected_cnt)) + return -EAGAIN; + } + __folio_migrate_mapping(mapping, newfolio, folio, expected_cnt); return MIGRATEPAGE_SUCCESS; } EXPORT_SYMBOL(folio_migrate_mapping);