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 41B02C83F14 for ; Tue, 29 Aug 2023 15:24:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BF6638E0029; Tue, 29 Aug 2023 11:24:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BA62D8E001A; Tue, 29 Aug 2023 11:24:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A6DFB8E0029; Tue, 29 Aug 2023 11:24:08 -0400 (EDT) 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 96BBA8E001A for ; Tue, 29 Aug 2023 11:24:08 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 65EC3401C6 for ; Tue, 29 Aug 2023 15:24:08 +0000 (UTC) X-FDA: 81177512976.20.68D5DFF Received: from mail-ej1-f48.google.com (mail-ej1-f48.google.com [209.85.218.48]) by imf28.hostedemail.com (Postfix) with ESMTP id 7AF3EC0015 for ; Tue, 29 Aug 2023 15:24:05 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=google.com header.s=20221208 header.b=gIE3+SeS; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf28.hostedemail.com: domain of yosryahmed@google.com designates 209.85.218.48 as permitted sender) smtp.mailfrom=yosryahmed@google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1693322645; 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-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=OzpeAN+lW4lnuBFNUjzlUToZyZ1j5VVEVY/cQHQ5ISc=; b=jtXjbDLgBwFdW5ZVdrlW+342gUGBmNjGxM5WIItYj5kcOTrGmD2P7IrBNPxviyVlWxp11d XOBdp2EvXdoAPW2Ei+judx0CWDH0IyLWuDhaR23n4Hb7EwWESg0ei4VQDyJfc/sA+TjbsP ZeEpxgSpvN9+rELL49EeMPhQqY3hWe4= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=google.com header.s=20221208 header.b=gIE3+SeS; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf28.hostedemail.com: domain of yosryahmed@google.com designates 209.85.218.48 as permitted sender) smtp.mailfrom=yosryahmed@google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1693322645; a=rsa-sha256; cv=none; b=pmdLV93qtDAgc59KNR3ddcrS+ooJ0UNdR6Lu3XEVh90Rr0flVPX1cutYKDIsxTK+KXNd7q dcu468jAs37dNY6hhYBsBB9oN/qjX+oxVLDd0zZdq5A+Ta2Y2/ejATnASmmajdoDxS3Wt5 7aF4rhCMGy13zu4RDiowRIVho0Yth34= Received: by mail-ej1-f48.google.com with SMTP id a640c23a62f3a-99bdeae1d0aso585126466b.1 for ; Tue, 29 Aug 2023 08:24:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1693322644; x=1693927444; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=OzpeAN+lW4lnuBFNUjzlUToZyZ1j5VVEVY/cQHQ5ISc=; b=gIE3+SeS9PGKpT7rHq/JaVxbPSQT8MNUMqvNMDjfmBJkWClm8pxZEEus8ath0clxxY v0sG1eoTpATDr8wnSTJHdDt32hjCxxYssPG3uDxo8GXbb/lk7yWjOyD6W2BHwgkraplS NMkTyX4NTdbJGWYq+AtvH18Sz2tJjsnU9z6Elc0l/08bcgwWVX7Jun62QgZ8m5iDEzIH thlbFbsGE1j0hn9Pzcgcuee2TBw0rxH6Q+KtsTJObb0Y10jVsmC5bm5oLmoep+J6cBr0 DF1Gnz5j1cqnyHU74KNEL4mvlxCt8bxGU3QdninJauuDTzsZDGPXFRkVcGO5uy7TB5UW qMLA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1693322644; x=1693927444; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=OzpeAN+lW4lnuBFNUjzlUToZyZ1j5VVEVY/cQHQ5ISc=; b=HejGHc9H+3VujAQN+11LMPEhzcI7RvB8eVG1Ax31m9E+c0zi4OMv0CxbESoJ/uG0/F lsCa/MZBHv7deMDVLczj7iGBgiEW7xZJVrzdH9+BpOur0ytwLvhRM+uKOZuXOLRelLqb WxqXd8MWIpDo58e9TyCDLWvTizgbp35QMcLb3GaLHVUtmkpwp0F4m6p3kTXHSbtJUUrW iYSq3pq4eguWGTNYVGxJo5Jhkl7/OBXRu4u26onSGHdhT1nf62PM6HqsiNTEipzTCT89 6wog+XjwNrqPlJpHH3DQEV+H7NP8/bKHw81Bxh0ceji3ierqY7y1Lq1RKYUH5teDUgZk XUTA== X-Gm-Message-State: AOJu0YwXoqbbFuYhCOizE/Hsi4LV2zNG0lrDlynkLwfy98BaJmqlTPIu ij9TnF7y6pEtzOMhzEInDHgtWCe0vvditgVujBH3TQ== X-Google-Smtp-Source: AGHT+IHlkI4JIvy/6XvTpJv2HVLUD9upOsoJifduwUKMfb1tWWTyzCBvCKhb+hJ/xctCqEFJVBXvJs+xbX0gjgf9bRo= X-Received: by 2002:a17:906:9e:b0:9a2:143e:a071 with SMTP id 30-20020a170906009e00b009a2143ea071mr8695044ejc.17.1693322643587; Tue, 29 Aug 2023 08:24:03 -0700 (PDT) MIME-Version: 1.0 References: <20230829024104.1505530-1-liushixin2@huawei.com> In-Reply-To: <20230829024104.1505530-1-liushixin2@huawei.com> From: Yosry Ahmed Date: Tue, 29 Aug 2023 08:23:26 -0700 Message-ID: Subject: Re: [PATCH v4] mm: vmscan: try to reclaim swapcache pages if no swap space To: Liu Shixin Cc: Huang Ying , Michal Hocko , Johannes Weiner , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , wangkefeng.wang@huawei.com, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 7AF3EC0015 X-Stat-Signature: x8uckggcjpkq1hf8wzh7uoqeepf4rt9j X-HE-Tag: 1693322645-583533 X-HE-Meta: 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 1eTVRt64 Aj1QfcE96G2TcO46qt6hHn+2hYGgwJeJVUt0RWS9uaLYLG9O3Jt0uRv/Fo6s2xTDjfq7YLiPjzb31t7nwzLUluIzS7yf9kDh7vav2xRVZGk5DGYFKXzOOWCGgHH6CmGRsWCbZJJpCD+0pJkymji7LOLc0Fb2fSEYhC0OdUPXjG1I0/XSEoQorWXJ50HwaSRdPPO7JhK+YpziV56KZyzqOmT07gtv98jeqTgCPBv7Llufd3TLU69Tw4MFQ0UrFQS/L4D4LGXL39XOc+OkH6XweQxjBDWYw5B1jS4ocsiVr+pHuhM5bmP+VYp1cvwh8XsH5oDZAwYFTg4HBCHGa+OF8ZodnztHg5mZZBvZq 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 Mon, Aug 28, 2023 at 6:46=E2=80=AFPM Liu Shixin = wrote: > > When spaces of swap devices are exhausted, only file pages can be reclaim= ed. > But there are still some swapcache pages in anon lru list. This can lead > to a premature out-of-memory. > > The problem is found with such step: > > Firstly, set a 9MB disk swap space, then create a cgroup with 10MB > memory limit, then runs an program to allocates about 15MB memory. > > The problem occurs occasionally, which may need about 100 times. The reproducer I used in v2 reproduces this very reliably and simply, could you link to it instead? https://lore.kernel.org/lkml/CAJD7tkZAfgncV+KbKr36=3DeDzMnT=3D9dZOT0dpMWcur= HLr6Do+GA@mail.gmail.com/ > > Fix it by checking number of swapcache pages in can_reclaim_anon_pages(). > If the number is not zero, return true either. Moreover, add a new bit > swapcache_only in struct scan_control to skip isolating anon pages that > are not swapcache when only swapcache pages can be reclaimed to accelerat= e > reclaim efficiency. > > Link: https://lore.kernel.org/linux-mm/14e15f31-f3d3-4169-8ed9-fb36e57cf5= 78@huawei.com/ > Signed-off-by: Liu Shixin > Tested-by: Yosry Ahmed Usually people add the difference from the previous version to make it easy to know what changed. I still prefer to add NR_SWAPCACHE to memcg1_stats. Anyway, the code looks good to me. With the updated reproducer link feel free to add: Reviewed-by: Yosry Ahmed > --- > include/linux/swap.h | 6 ++++++ > mm/memcontrol.c | 8 ++++++++ > mm/vmscan.c | 29 +++++++++++++++++++++++++++-- > 3 files changed, 41 insertions(+), 2 deletions(-) > > diff --git a/include/linux/swap.h b/include/linux/swap.h > index 456546443f1f..0318e918bfa4 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -669,6 +669,7 @@ static inline void mem_cgroup_uncharge_swap(swp_entry= _t entry, unsigned int nr_p > } > > extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg); > +extern long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg); > extern bool mem_cgroup_swap_full(struct folio *folio); > #else > static inline void mem_cgroup_swapout(struct folio *folio, swp_entry_t e= ntry) > @@ -691,6 +692,11 @@ static inline long mem_cgroup_get_nr_swap_pages(stru= ct mem_cgroup *memcg) > return get_nr_swap_pages(); > } > > +static inline long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *= memcg) > +{ > + return total_swapcache_pages(); > +} > + > static inline bool mem_cgroup_swap_full(struct folio *folio) > { > return vm_swap_full(); > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index e8ca4bdcb03c..c465829db92b 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -7567,6 +7567,14 @@ long mem_cgroup_get_nr_swap_pages(struct mem_cgrou= p *memcg) > return nr_swap_pages; > } > > +long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg) > +{ > + if (mem_cgroup_disabled()) > + return total_swapcache_pages(); > + > + return memcg_page_state(memcg, NR_SWAPCACHE); > +} > + > bool mem_cgroup_swap_full(struct folio *folio) > { > struct mem_cgroup *memcg; > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 1080209a568b..e73e2df8828d 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -137,6 +137,9 @@ struct scan_control { > /* Always discard instead of demoting to lower tier memory */ > unsigned int no_demotion:1; > > + /* Swap space is exhausted, only reclaim swapcache for anon LRU *= / > + unsigned int swapcache_only:1; > + > /* Allocation order */ > s8 order; > > @@ -613,10 +616,20 @@ static inline bool can_reclaim_anon_pages(struct me= m_cgroup *memcg, > */ > if (get_nr_swap_pages() > 0) > return true; > + /* Is there any swapcache pages to reclaim? */ > + if (total_swapcache_pages() > 0) { > + sc->swapcache_only =3D 1; > + return true; > + } > } else { > /* Is the memcg below its swap limit? */ > if (mem_cgroup_get_nr_swap_pages(memcg) > 0) > return true; > + /* Is there any swapcache pages in memcg to reclaim? */ > + if (mem_cgroup_get_nr_swapcache_pages(memcg) > 0) { > + sc->swapcache_only =3D 1; > + return true; > + } > } > > /* > @@ -2280,6 +2293,19 @@ static bool skip_cma(struct folio *folio, struct s= can_control *sc) > } > #endif > > +static bool skip_isolate(struct folio *folio, struct scan_control *sc, > + enum lru_list lru) > +{ > + if (folio_zonenum(folio) > sc->reclaim_idx) > + return true; > + if (skip_cma(folio, sc)) > + return true; > + if (unlikely(sc->swapcache_only && !is_file_lru(lru) && > + !folio_test_swapcache(folio))) > + return true; > + return false; > +} > + > /* > * Isolating page from the lruvec to fill in @dst list by nr_to_scan tim= es. > * > @@ -2326,8 +2352,7 @@ static unsigned long isolate_lru_folios(unsigned lo= ng nr_to_scan, > nr_pages =3D folio_nr_pages(folio); > total_scan +=3D nr_pages; > > - if (folio_zonenum(folio) > sc->reclaim_idx || > - skip_cma(folio, sc)) { > + if (skip_isolate(folio, sc, lru)) { > nr_skipped[folio_zonenum(folio)] +=3D nr_pages; > move_to =3D &folios_skipped; > goto move; > -- > 2.25.1 >