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 0B009C05027 for ; Tue, 14 Feb 2023 17:46:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6CCFA6B0071; Tue, 14 Feb 2023 12:46:35 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 67CD16B0075; Tue, 14 Feb 2023 12:46:35 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 59D536B0078; Tue, 14 Feb 2023 12:46:35 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 4AC986B0071 for ; Tue, 14 Feb 2023 12:46:35 -0500 (EST) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 1C57FA0E9D for ; Tue, 14 Feb 2023 17:46:35 +0000 (UTC) X-FDA: 80466627150.22.047B20F Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf06.hostedemail.com (Postfix) with ESMTP id 431FA180009 for ; Tue, 14 Feb 2023 17:46:32 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=bi78MPmB; spf=pass (imf06.hostedemail.com: domain of sj@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1676396792; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=kxaTN0/bApSIgN/iIK499glwPckIjFo9AG6KgJeY778=; b=07Jpp8G5M2fxnNFW3QGOe1khaADqthhf0fEQYtuOUQVoQgE85qDM/8H5ZCFNr6gRoTvNy6 GHIkMZe6eFKkyE+qt22fhrAT1T5f5qXVuRhJ2KsUDWlOh82YH7Rv32Il8GXRQyy3kNebMx 5SH7oX3wXpH7Oe+kbTt5o35v7Efz/2Q= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=bi78MPmB; spf=pass (imf06.hostedemail.com: domain of sj@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1676396792; a=rsa-sha256; cv=none; b=ZPAUvqhkDsmk6kKXB0fluXKTDtRDxUqa9wtnsvVcFwRR8hkw7YnjSe55jdlbMTADc1uljA 621ajp+Nupe7m/+oaueK8f3Py4YxtF1PkTxttlZbctvJRa7kCszWaI4ZDu6jCPofSj9yOk CYG1v7xK+F4XF5MKhDRNuInsRIJnuac= Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A5DA4B81E48; Tue, 14 Feb 2023 17:46:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8A40C433D2; Tue, 14 Feb 2023 17:46:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1676396789; bh=MEG6NlLEiDkZKTJsLOd2zm/nDm26I6+i8VdF4xtbs18=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bi78MPmBkukT5Jrfo8mnvXqS2i2OFtZRbpqm7+zOZPMNAjBb/E3vsgivICgeyqC4b PoEJ1ryoP+jn/irksPJBXMwnY1iEU7BNS52x59OejNuV12o2w4udhcum2TRMJlWbbB Al1YeJ5X5BI+P19U8qtDmhjfj6yg6qr2BiaaoOIQjMpwJoyY6VPz3u9azgy6kMKxp9 qMAM7+cyRUg8RRkxBOH9gULqR5KRnO0NdjswwDvJiTITk0jHDkTM82ImdW2bggg52S Rrq4i3YcXL84BO3tHhlhH8OnmMV5e7vy8c1gxln1DqnrdwbtIDmfDvkKo8hnX+XLnV 5IG0OglfDXBZg== From: SeongJae Park To: Baolin Wang Cc: akpm@linux-foundation.org, torvalds@linux-foundation.org, sj@kernel.org, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeelb@google.com, muchun.song@linux.dev, naoya.horiguchi@nec.com, linmiaohe@huawei.com, david@redhat.com, osalvador@suse.de, mike.kravetz@oracle.com, willy@infradead.org, damon@lists.linux.dev, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/4] mm: change to return bool for folio_isolate_lru() Date: Tue, 14 Feb 2023 17:46:26 +0000 Message-Id: <20230214174626.71336-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <7abe2897803410fdc8f167b46bb5b0467de0e3c9.1676382188.git.baolin.wang@linux.alibaba.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 431FA180009 X-Rspam-User: X-Stat-Signature: yoiguddyrt14at77z8697n7wtizh6jh9 X-HE-Tag: 1676396792-905789 X-HE-Meta: U2FsdGVkX18uN7B0ouxcr69Kwtwb319os5zsl2OfJkR7W4GpmEW3jaELE37cQli8VTFh3WAQBj7wBIp/ThxsBEkHt2+CQNw7SSm/rB0jLmqAAXEN/Ox6BrikdpwfiFa3RvziHOftSG56eLd5Y5I29+TT85PlPiUAYcOP5a2/FoMykc7Iuhhu0J/tvGU5/3Gp4u61OSmPjXp0AMdOt8CrViDCqCLp3fH1Q/Ug0iiCJ7l1ijZcfyCTl5NAkWtJKvDELt8lq6XG28ehpoaqqhi4KLdwtl0Jo0UoQc2r0Z9a2SDIDFdhFY1WdiRfW2L1t8p3mII1I/OrCP0fOa7fttPirOGLiCyjLRXU6yFHu2GpLwzCJB2MY6LvH8MGZHti9sIKZAJT3sxqEE3npsIgepsMLguXFqDH/A7BtnY+60g6HQZVGTyZ6s+15JPVtrOAMmGF7/OGk2LaEftCd1j03hJetGIg6YSX5o/4rUt0tKqxPtTxQrkyvgFmh1OOeEkDKKmFJsU1hJstlfIxTBllCFAeSGlS7Lbvd6GgDHEmEGBbkLOJ/FM8H5N9N/u5/W+SjMQOK4WXf+NVDE230jDie5nDVLpoqT4rZHw0tOwfCdgUNtLOfOHA5lM37Vl4sccMoSWx6Ymg9ijijkF+Qnm4FSEWnyMimjzgGMJzpilmYhP7dpswkPUjBnBtPNn6mUxqWAmjEh/EK34PorhrI42wI/hFBhHIMPkQgMqcsIalqFvmRFfyPLGbYU9rJA5Sl0OZkZE4EupBrlVvT5cZqqK5VzuvRWRt++2/DTPt0ZAF0TMxRdB7VATRRPSIUu7ILl+OEVQLhv7BcLO56v2JOQN43YdNlFMj2gRxjIOScVN7CmNy209lQ1wTNtsZuAVHnNEMbFzsbV8QlsLr97Z474nvSHCwPc1ELrPDWnNUV8h7wBup4AIJ9WCtv5NO2gf2tUKcQbqvO4dAZFsCMKllFE87xxa 6W3DWzNr 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 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 Tue, 14 Feb 2023 21:59:29 +0800 Baolin Wang wrote: > Now the folio_isolate_lru() did not return a boolean value to indicate > isolation success or not, however below code checking the return value > can make people think that it was a boolean success/failure thing, which > makes people easy to make mistakes (see the fix patch[1]). > > if (folio_isolate_lru(folio)) > continue; > > Thus it's better to check the negative error value expilictly returned by > folio_isolate_lru(), which makes code more clear per Linus's suggestion[2]. > Moreover Matthew suggested we can convert the isolation functions to return > a boolean[3], since most users did not care about the negative error value, > and can also remove the confusing of checking return value. > > So this patch converts the folio_isolate_lru() to return a boolean value, > which means return 'true' to indicate the folio isolation is successful, and > 'false' means a failure to isolation. Meanwhile changing all users' logic of > checking the isolation state. > > No functional changes intended. > > [1] https://lore.kernel.org/all/20230131063206.28820-1-Kuan-Ying.Lee@mediatek.com/T/#u > [2] https://lore.kernel.org/all/CAHk-=wiBrY+O-4=2mrbVyxR+hOqfdJ=Do6xoucfJ9_5az01L4Q@mail.gmail.com/ > [3] https://lore.kernel.org/all/Y+sTFqwMNAjDvxw3@casper.infradead.org/ > > Signed-off-by: Baolin Wang > --- > mm/damon/paddr.c | 2 +- > mm/folio-compat.c | 8 +++++++- > mm/gup.c | 2 +- > mm/internal.h | 2 +- > mm/khugepaged.c | 2 +- > mm/madvise.c | 4 ++-- > mm/mempolicy.c | 2 +- > mm/vmscan.c | 10 +++++----- > 8 files changed, 19 insertions(+), 13 deletions(-) > > diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c > index b4df9b9bcc0a..607bb69e526c 100644 > --- a/mm/damon/paddr.c > +++ b/mm/damon/paddr.c > @@ -246,7 +246,7 @@ static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s) > > folio_clear_referenced(folio); > folio_test_clear_young(folio); > - if (folio_isolate_lru(folio)) { > + if (!folio_isolate_lru(folio)) { > folio_put(folio); > continue; > } > diff --git a/mm/folio-compat.c b/mm/folio-compat.c > index 18c48b557926..540373cf904e 100644 > --- a/mm/folio-compat.c > +++ b/mm/folio-compat.c > @@ -115,9 +115,15 @@ EXPORT_SYMBOL(grab_cache_page_write_begin); > > int isolate_lru_page(struct page *page) > { > + bool ret; > + > if (WARN_RATELIMIT(PageTail(page), "trying to isolate tail page")) > return -EBUSY; > - return folio_isolate_lru((struct folio *)page); > + ret = folio_isolate_lru((struct folio *)page); > + if (ret) > + return 0; > + > + return -EBUSY; > } > > void putback_lru_page(struct page *page) > diff --git a/mm/gup.c b/mm/gup.c > index b0885f70579c..eab18ba045db 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -1939,7 +1939,7 @@ static unsigned long collect_longterm_unpinnable_pages( > drain_allow = false; > } > > - if (folio_isolate_lru(folio)) > + if (!folio_isolate_lru(folio)) > continue; > > list_add_tail(&folio->lru, movable_page_list); > diff --git a/mm/internal.h b/mm/internal.h > index dfb37e94e140..8645e8496537 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -188,7 +188,7 @@ pgprot_t __init early_memremap_pgprot_adjust(resource_size_t phys_addr, > * in mm/vmscan.c: > */ > int isolate_lru_page(struct page *page); > -int folio_isolate_lru(struct folio *folio); > +bool folio_isolate_lru(struct folio *folio); > void putback_lru_page(struct page *page); > void folio_putback_lru(struct folio *folio); > extern void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason); > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index a5d32231bfad..cee659cfa3c1 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -2047,7 +2047,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, > goto out_unlock; > } > > - if (folio_isolate_lru(folio)) { > + if (!folio_isolate_lru(folio)) { > result = SCAN_DEL_PAGE_LRU; > goto out_unlock; > } > diff --git a/mm/madvise.c b/mm/madvise.c > index 5a5a687d03c2..c2202f51e9dd 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -406,7 +406,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd, > folio_clear_referenced(folio); > folio_test_clear_young(folio); > if (pageout) { > - if (!folio_isolate_lru(folio)) { > + if (folio_isolate_lru(folio)) { > if (folio_test_unevictable(folio)) > folio_putback_lru(folio); > else > @@ -500,7 +500,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd, > folio_clear_referenced(folio); > folio_test_clear_young(folio); > if (pageout) { > - if (!folio_isolate_lru(folio)) { > + if (folio_isolate_lru(folio)) { > if (folio_test_unevictable(folio)) > folio_putback_lru(folio); > else > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 0919c7a719d4..2751bc3310fd 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -1033,7 +1033,7 @@ static int migrate_folio_add(struct folio *folio, struct list_head *foliolist, > * expensive, so check the estimated mapcount of the folio instead. > */ > if ((flags & MPOL_MF_MOVE_ALL) || folio_estimated_sharers(folio) == 1) { > - if (!folio_isolate_lru(folio)) { > + if (folio_isolate_lru(folio)) { > list_add_tail(&folio->lru, foliolist); > node_stat_mod_folio(folio, > NR_ISOLATED_ANON + folio_is_file_lru(folio), > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 34535bbd4fe9..7658b40df947 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2337,12 +2337,12 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan, > * (2) The lru_lock must not be held. > * (3) Interrupts must be enabled. > * > - * Return: 0 if the folio was removed from an LRU list. > - * -EBUSY if the folio was not on an LRU list. > + * Return: true if the folio was removed from an LRU list. > + * false if the folio was not on an LRU list. > */ > -int folio_isolate_lru(struct folio *folio) > +bool folio_isolate_lru(struct folio *folio) > { > - int ret = -EBUSY; > + bool ret = false; > > VM_BUG_ON_FOLIO(!folio_ref_count(folio), folio); > > @@ -2353,7 +2353,7 @@ int folio_isolate_lru(struct folio *folio) > lruvec = folio_lruvec_lock_irq(folio); > lruvec_del_folio(lruvec, folio); > unlock_page_lruvec_irq(lruvec); > - ret = 0; > + ret = true; > } > > return ret; > -- > 2.27.0 Reviewed-by: SeongJae Park Thanks, SJ