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[2620:137:e000::1:20]) by mx.google.com with ESMTP id hw9-20020a170907a0c900b0078dce2b1985si11987716ejc.134.2022.12.04.19.10.23; Sun, 04 Dec 2022 19:10:53 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=huawei.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231182AbiLECru (ORCPT + 99 others); Sun, 4 Dec 2022 21:47:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46592 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230307AbiLECrs (ORCPT ); Sun, 4 Dec 2022 21:47:48 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0281365D0 for ; Sun, 4 Dec 2022 18:47:47 -0800 (PST) Received: from dggpemm500002.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4NQScd5mJCzRpkX; Mon, 5 Dec 2022 10:46:57 +0800 (CST) Received: from localhost.localdomain (10.175.112.125) by dggpemm500002.china.huawei.com (7.185.36.229) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 5 Dec 2022 10:47:44 +0800 From: Chen Wandun To: , , , , , , CC: Subject: [PATCH] swapfile: fix uncorrect statistical count about free swap Date: Mon, 5 Dec 2022 10:47:26 +0800 Message-ID: <20221205024726.3111808-1-chenwandun@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.175.112.125] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpemm500002.china.huawei.com (7.185.36.229) X-CFilter-Loop: Reflected X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1751341966873376272?= X-GMAIL-MSGID: =?utf-8?q?1751341966873376272?= The counter of free swap turn to negtive during swapoff, this phenomenon can be observed in oom log, such as: 1226 total pagecache pages 47 pages in swap cache Swap cache stats: add 119633, delete 119814, find 26832/82125 Free swap = -31796kB Total swap = 0kB 1048576 pages RAM Subtract the size of swap partition from free swap should put behind try_to_unuse, otherwise, it will result in negtive counter if swap partition is in use. Fixes: ec8acf20afb8 ("swap: add per-partition lock for swapfile") Signed-off-by: Chen Wandun --- mm/swapfile.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 72e481aacd5d..5b9b695be84b 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -2316,8 +2316,6 @@ static void setup_swap_info(struct swap_info_struct *p, int prio, static void _enable_swap_info(struct swap_info_struct *p) { p->flags |= SWP_WRITEOK; - atomic_long_add(p->pages, &nr_swap_pages); - total_swap_pages += p->pages; assert_spin_locked(&swap_lock); /* @@ -2353,6 +2351,8 @@ static void enable_swap_info(struct swap_info_struct *p, int prio, spin_lock(&swap_lock); spin_lock(&p->lock); _enable_swap_info(p); + atomic_long_add(p->pages, &nr_swap_pages); + total_swap_pages += p->pages; spin_unlock(&p->lock); spin_unlock(&swap_lock); } @@ -2444,8 +2444,6 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) least_priority++; } plist_del(&p->list, &swap_active_head); - atomic_long_sub(p->pages, &nr_swap_pages); - total_swap_pages -= p->pages; p->flags &= ~SWP_WRITEOK; spin_unlock(&p->lock); spin_unlock(&swap_lock); @@ -2500,6 +2498,8 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) spin_lock(&p->lock); } + atomic_long_sub(p->pages, &nr_swap_pages); + total_swap_pages -= p->pages; swap_file = p->swap_file; old_block_size = p->old_block_size; p->swap_file = NULL;