From patchwork Wed Nov 3 10:51:14 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Baolin Wang X-Patchwork-Id: 12600565 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C38D5C433F5 for ; Wed, 3 Nov 2021 10:51:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3FD816109F for ; Wed, 3 Nov 2021 10:51:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 3FD816109F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 9DA466B0071; Wed, 3 Nov 2021 06:51:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 962D16B0072; Wed, 3 Nov 2021 06:51:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 877E8940007; Wed, 3 Nov 2021 06:51:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0121.hostedemail.com [216.40.44.121]) by kanga.kvack.org (Postfix) with ESMTP id 79D006B0071 for ; Wed, 3 Nov 2021 06:51:33 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 3E63E8249980 for ; Wed, 3 Nov 2021 10:51:33 +0000 (UTC) X-FDA: 78767302866.13.C7037D1 Received: from out30-45.freemail.mail.aliyun.com (out30-45.freemail.mail.aliyun.com [115.124.30.45]) by imf09.hostedemail.com (Postfix) with ESMTP id 389A83000112 for ; Wed, 3 Nov 2021 10:51:30 +0000 (UTC) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04400;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0UutTv9C_1635936687; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0UutTv9C_1635936687) by smtp.aliyun-inc.com(127.0.0.1); Wed, 03 Nov 2021 18:51:27 +0800 From: Baolin Wang To: akpm@linux-foundation.org, rostedt@goodmis.org, mingo@redhat.com Cc: ziy@nvidia.com, shy828301@gmail.com, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH 1/3] mm: migrate: Fix the return value of migrate_pages() Date: Wed, 3 Nov 2021 18:51:14 +0800 Message-Id: X-Mailer: git-send-email 1.8.3.1 In-Reply-To: References: In-Reply-To: References: X-Stat-Signature: f7x88zj4focxx1gteysjqa8q7mjgtkak X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 389A83000112 Authentication-Results: imf09.hostedemail.com; dkim=none; spf=pass (imf09.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.45 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com; dmarc=pass (policy=none) header.from=alibaba.com X-HE-Tag: 1635936690-469057 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: As Zi Yan pointed out, the syscall move_pages() can return a non-migrated number larger than the number of pages the users tried to migrate, when a THP page is failed to migrate. This is confusing for users. Since other migration scenarios do not care about the actual non-migrated number of pages except the memory compaction migration which will fix in following patch. Thus we can change the return value to return the number of {normal page, THP, hugetlb} instead to avoid this issue, meanwhile we should still keep the migration counters using the number of normal pages. Signed-off-by: Baolin Wang --- mm/migrate.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index a11e948..00b8922 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1428,7 +1428,7 @@ static inline int try_split_thp(struct page *page, struct page **page2, * @mode: The migration mode that specifies the constraints for * page migration, if any. * @reason: The reason for page migration. - * @ret_succeeded: Set to the number of pages migrated successfully if + * @ret_succeeded: Set to the number of normal pages migrated successfully if * the caller passes a non-NULL pointer. * * The function returns after 10 attempts or if no pages are movable any more @@ -1436,7 +1436,7 @@ static inline int try_split_thp(struct page *page, struct page **page2, * It is caller's responsibility to call putback_movable_pages() to return pages * to the LRU or free list only if ret != 0. * - * Returns the number of pages that were not migrated, or an error code. + * Returns the number of {normal page, THP} that were not migrated, or an error code. */ int migrate_pages(struct list_head *from, new_page_t get_new_page, free_page_t put_new_page, unsigned long private, @@ -1445,6 +1445,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, int retry = 1; int thp_retry = 1; int nr_failed = 0; + int nr_failed_pages = 0; int nr_succeeded = 0; int nr_thp_succeeded = 0; int nr_thp_failed = 0; @@ -1517,7 +1518,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, } nr_thp_failed++; - nr_failed += nr_subpages; + nr_failed_pages += nr_subpages; break; } @@ -1537,7 +1538,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, } nr_thp_failed++; - nr_failed += nr_subpages; + nr_failed_pages += nr_subpages; goto out; } nr_failed++; @@ -1566,7 +1567,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, */ if (is_thp) { nr_thp_failed++; - nr_failed += nr_subpages; + nr_failed_pages += nr_subpages; break; } nr_failed++; @@ -1575,8 +1576,9 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, } } nr_failed += retry + thp_retry; + nr_failed_pages += nr_failed; nr_thp_failed += thp_retry; - rc = nr_failed; + rc = nr_failed + nr_thp_failed; out: /* * Put the permanent failure page back to migration list, they @@ -1585,11 +1587,11 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, list_splice(&ret_pages, from); count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); - count_vm_events(PGMIGRATE_FAIL, nr_failed); + count_vm_events(PGMIGRATE_FAIL, nr_failed_pages); count_vm_events(THP_MIGRATION_SUCCESS, nr_thp_succeeded); count_vm_events(THP_MIGRATION_FAIL, nr_thp_failed); count_vm_events(THP_MIGRATION_SPLIT, nr_thp_split); - trace_mm_migrate_pages(nr_succeeded, nr_failed, nr_thp_succeeded, + trace_mm_migrate_pages(nr_succeeded, nr_failed_pages, nr_thp_succeeded, nr_thp_failed, nr_thp_split, mode, reason); if (!swapwrite)