From patchwork Tue Feb 6 11:21:29 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kefeng Wang X-Patchwork-Id: 13547049 Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A7BD812EBF0 for ; Tue, 6 Feb 2024 11:21:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.191 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707218510; cv=none; b=kP28n5aRYg02x1XVlpUTQEA06fq2WCDJTt0LbCah+fWl7o4AYq3qHjFcu/dh8+IlubElwrt5dacwIDSnQev02a9TM/IAidw8Xz1D/Z0Y6xAXIGSjCBuGMw89iDAOza6PZukcur088/yYWDqOES7fxyEYskuTBFn49iU0ifmuGJs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707218510; c=relaxed/simple; bh=VVRpiIX6spEAIhGUwRjcivCyd92PWvZcp4CPAkmtyCk=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=KjGHXi9Ih/lvCfiU9Dxabi0ClwlnTPAz7c2HVmUue/KLpyJ8JULji8DUHA0aW8QVvxVLEBI2Z4TKEXNa+KTT2vVf5/UdVniM/gcuZKi9ZPZ7w/CgK8az5C2J5KYnvrQiA9bKggoG10T/E0lE70pEwVcuRh+NC3rDjqZMoa21Us0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.191 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.44]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4TTgkt69Stz1gyfQ; Tue, 6 Feb 2024 19:19:50 +0800 (CST) Received: from dggpemm100001.china.huawei.com (unknown [7.185.36.93]) by mail.maildlp.com (Postfix) with ESMTPS id 6B9D2140412; Tue, 6 Feb 2024 19:21:46 +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_128_GCM_SHA256) id 15.1.2507.35; Tue, 6 Feb 2024 19:21:45 +0800 From: Kefeng Wang To: Andrew Morton , CC: Tony Luck , Naoya Horiguchi , Miaohe Lin , Matthew Wilcox , David Hildenbrand , Muchun Song , Benjamin LaHaise , , , , Kefeng Wang Subject: [PATCH rfcv2 06/11] mm: migrate: split folio_migrate_mapping() Date: Tue, 6 Feb 2024 19:21:29 +0800 Message-ID: <20240206112134.1479464-7-wangkefeng.wang@huawei.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20240206112134.1479464-1-wangkefeng.wang@huawei.com> References: <20240206112134.1479464-1-wangkefeng.wang@huawei.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm100001.china.huawei.com (7.185.36.93) The folio_migrate_mapping() function is splitted into two parts, folio_refs_check_and_freeze() and folio_replace_mapping_and_unfreeze(), 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 --- mm/migrate.c | 74 +++++++++++++++++++++++++++++----------------------- 1 file changed, 42 insertions(+), 32 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index 2dcd0d422056..1db93b5eb819 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -390,50 +390,49 @@ static int folio_expected_refs(struct address_space *mapping, } /* - * Replace the page 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 int folio_refs_check_and_freeze(struct address_space *mapping, + struct folio *folio, int expected_cnt) +{ + if (!mapping) { + if (folio_ref_count(folio) != expected_cnt) + return -EAGAIN; + } else { + if (!folio_ref_freeze(folio, expected_cnt)) + return -EAGAIN; + } + + return 0; +} + +/* The folio refcount must be freezed if folio with a mapping */ +static void folio_replace_mapping_and_unfreeze(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); + /* Now we know that no one else is looking at the folio */ 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. - */ newfolio->index = folio->index; newfolio->mapping = folio->mapping; folio_ref_add(newfolio, nr); /* add cache reference */ @@ -449,7 +448,7 @@ 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); @@ -463,22 +462,22 @@ 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. */ @@ -515,7 +514,18 @@ 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 ret, expected = folio_expected_refs(mapping, folio) + extra_count; + + ret = folio_refs_check_and_freeze(mapping, folio, expected); + if (ret) + return ret; + folio_replace_mapping_and_unfreeze(mapping, newfolio, folio, expected); return MIGRATEPAGE_SUCCESS; } EXPORT_SYMBOL(folio_migrate_mapping);