From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8C31C47404 for ; Fri, 4 Oct 2019 13:09:27 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9272F222BE for ; Fri, 4 Oct 2019 13:09:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="i1OFqRe1" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9272F222BE Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=yandex-team.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3299E6B0003; Fri, 4 Oct 2019 09:09:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2B28B6B0005; Fri, 4 Oct 2019 09:09:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 17A486B0007; Fri, 4 Oct 2019 09:09:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0189.hostedemail.com [216.40.44.189]) by kanga.kvack.org (Postfix) with ESMTP id E3A706B0003 for ; Fri, 4 Oct 2019 09:09:26 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 90D2A180AD803 for ; Fri, 4 Oct 2019 13:09:26 +0000 (UTC) X-FDA: 76006133532.16.ring37_524b96da05519 X-HE-Tag: ring37_524b96da05519 X-Filterd-Recvd-Size: 3729 Received: from forwardcorp1p.mail.yandex.net (forwardcorp1p.mail.yandex.net [77.88.29.217]) by imf41.hostedemail.com (Postfix) with ESMTP for ; Fri, 4 Oct 2019 13:09:25 +0000 (UTC) Received: from mxbackcorp2j.mail.yandex.net (mxbackcorp2j.mail.yandex.net [IPv6:2a02:6b8:0:1619::119]) by forwardcorp1p.mail.yandex.net (Yandex) with ESMTP id 1ED7D2E0A1C; Fri, 4 Oct 2019 16:09:23 +0300 (MSK) Received: from iva8-b53eb3f76dc7.qloud-c.yandex.net (iva8-b53eb3f76dc7.qloud-c.yandex.net [2a02:6b8:c0c:2ca1:0:640:b53e:b3f7]) by mxbackcorp2j.mail.yandex.net (nwsmtp/Yandex) with ESMTP id VpcdspqVFC-9MNGcrnJ; Fri, 04 Oct 2019 16:09:23 +0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1570194563; bh=yAPYaJ3oJgwpDyUBZu6nyxA51pk4jSRQtkpSzJ5+NBA=; h=Message-ID:Date:To:From:Subject:Cc; b=i1OFqRe1V+4wqbQRoJPNi2tgjj9/yhnp69XlwSBAqiTBuAgTNCBXXAPCOLY6clB0Z mJg18K6W3/PprBqB3uDMD79kCGuJn107RDoWkcX39kx64Keqzmc+TPhIIrGFJ0W37a OMLt9TEj0iSCJu35iUCfASNFufVFQk75bxkUMvls= Authentication-Results: mxbackcorp2j.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-red.dhcp.yndx.net (dynamic-red.dhcp.yndx.net [2a02:6b8:0:40c:3d4d:a9cb:ef29:4bb1]) by iva8-b53eb3f76dc7.qloud-c.yandex.net (nwsmtp/Yandex) with ESMTPSA id GTiLEDP0fi-9MHuZTQ6; Fri, 04 Oct 2019 16:09:22 +0300 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client certificate not present) Subject: [PATCH v2] mm/swap: piggyback lru_add_drain_all() calls From: Konstantin Khlebnikov To: linux-mm@kvack.org, Andrew Morton Cc: Michal Hocko , linux-kernel@vger.kernel.org, Matthew Wilcox Date: Fri, 04 Oct 2019 16:09:22 +0300 Message-ID: <157019456205.3142.3369423180908482020.stgit@buzz> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit 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: This is very slow operation. There is no reason to do it again if somebody else already drained all per-cpu vectors while we waited for lock. Piggyback on drain started and finished while we waited for lock: all pages pended at the time of our enter were drained from vectors. Callers like POSIX_FADV_DONTNEED retry their operations once after draining per-cpu vectors when pages have unexpected references. Signed-off-by: Konstantin Khlebnikov --- mm/swap.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/mm/swap.c b/mm/swap.c index 38c3fa4308e2..5ba948a9d82a 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -708,9 +708,10 @@ static void lru_add_drain_per_cpu(struct work_struct *dummy) */ void lru_add_drain_all(void) { + static seqcount_t seqcount = SEQCNT_ZERO(seqcount); static DEFINE_MUTEX(lock); static struct cpumask has_work; - int cpu; + int cpu, seq; /* * Make sure nobody triggers this path before mm_percpu_wq is fully @@ -719,7 +720,19 @@ void lru_add_drain_all(void) if (WARN_ON(!mm_percpu_wq)) return; + seq = raw_read_seqcount_latch(&seqcount); + mutex_lock(&lock); + + /* + * Piggyback on drain started and finished while we waited for lock: + * all pages pended at the time of our enter were drained from vectors. + */ + if (__read_seqcount_retry(&seqcount, seq)) + goto done; + + raw_write_seqcount_latch(&seqcount); + cpumask_clear(&has_work); for_each_online_cpu(cpu) { @@ -740,6 +753,7 @@ void lru_add_drain_all(void) for_each_cpu(cpu, &has_work) flush_work(&per_cpu(lru_add_drain_work, cpu)); +done: mutex_unlock(&lock); } #else