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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 912E6C433F5 for ; Tue, 21 Dec 2021 08:43:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 211BD6B007E; Tue, 21 Dec 2021 03:43:24 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1C1606B0080; Tue, 21 Dec 2021 03:43:24 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0B0EC6B0081; Tue, 21 Dec 2021 03:43:24 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0100.hostedemail.com [216.40.44.100]) by kanga.kvack.org (Postfix) with ESMTP id F230A6B007E for ; Tue, 21 Dec 2021 03:43:23 -0500 (EST) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id B4DD48910F for ; Tue, 21 Dec 2021 08:43:23 +0000 (UTC) X-FDA: 78941162286.16.0DB95E1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf01.hostedemail.com (Postfix) with ESMTP id 89D7540032 for ; Tue, 21 Dec 2021 08:43:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=DYR2S5ewk4HUFUjd2HbH/xwOxwzvreGNjIN9pC8vplc=; b=MTEMVoOLUCV3oj51jPjYvc8ECh TQg2seoX0W/DIVBzQBkbhHcJFOnhA1Mn+TqGFRv26H5S7qjois4MqVShBC56jMuC8D8Jaz10SdytD GIJkAXuXWKSIb8XEg7D2v8FCpoXYn+IyhwbLQKjufnTgD63t0Y7zovpg7JNkGmS3E4mq0kkZHan+l Ek9nMP1ZVgEkFlb7UKygAuSl+s+/XvbIlUMmVJz+QO4vQRremO27cC33IjTFz52YlfV9gbX2jTijo JJ4xsu2HZmP2LVDTBwhgPk1FpocYBX+1I6NHCyKq8ThqUNDQ8oweHA7vbQrAGWvwoi30LY7sOLCdp g9Dlh2qQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mzaju-005xrI-BI; Tue, 21 Dec 2021 08:43:18 +0000 Date: Tue, 21 Dec 2021 00:43:18 -0800 From: Christoph Hellwig To: NeilBrown Cc: Trond Myklebust , Anna Schumaker , Chuck Lever , Andrew Morton , Mel Gorman , Christoph Hellwig , David Howells , linux-nfs@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 05/18] MM: reclaim mustn't enter FS for SWP_FS_OPS swap-space Message-ID: References: <163969801519.20885.3977673503103544412.stgit@noble.brown> <163969850295.20885.4255989535187500085.stgit@noble.brown> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <163969850295.20885.4255989535187500085.stgit@noble.brown> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 89D7540032 X-Stat-Signature: 96nr74oq3jy45crqajannuaus6fg5huy Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=MTEMVoOL; spf=none (imf01.hostedemail.com: domain of BATV+1bb9050bde7847c37d79+6694+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+1bb9050bde7847c37d79+6694+infradead.org+hch@bombadil.srs.infradead.org; dmarc=none X-HE-Tag: 1640076196-205366 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: On Fri, Dec 17, 2021 at 10:48:22AM +1100, NeilBrown wrote: > +static bool test_may_enter_fs(struct page *page, gfp_t gfp_mask) > +{ > + if (gfp_mask & __GFP_FS) > + return true; > + if (!PageSwapCache(page) || !(gfp_mask & __GFP_IO)) > + return false; > + /* We can "enter_fs" for swap-cache with only __GFP_IO > + * providing this isn't SWP_FS_OPS. > + * ->flags can be updated non-atomicially (scan_swap_map_slots), > + * but that will never affect SWP_FS_OPS, so the data_race > + * is safe. > + */ > + return !data_race(page_swap_info(page)->flags & SWP_FS_OPS); Nit: the normal kernel comment style uses an empty /* line to start the comment. > @@ -1514,8 +1529,7 @@ static unsigned int shrink_page_list(struct list_head *page_list, > if (!sc->may_unmap && page_mapped(page)) > goto keep_locked; > > - may_enter_fs = (sc->gfp_mask & __GFP_FS) || > - (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); > + may_enter_fs = test_may_enter_fs(page, sc->gfp_mask); > > /* > * The number of dirty pages determines if a node is marked > @@ -1683,7 +1697,8 @@ static unsigned int shrink_page_list(struct list_head *page_list, > goto activate_locked_split; > } > > - may_enter_fs = true; > + may_enter_fs = test_may_enter_fs(page, > + sc->gfp_mask); Now that may_enter_fs is always reset using test_may_enter_fs, do we even need the local variable?