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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7804AC41513 for ; Wed, 2 Aug 2023 15:58:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235489AbjHBP6i (ORCPT ); Wed, 2 Aug 2023 11:58:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235430AbjHBP6d (ORCPT ); Wed, 2 Aug 2023 11:58:33 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 84B36BA; Wed, 2 Aug 2023 08:58:31 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1A9BF6199A; Wed, 2 Aug 2023 15:58:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 68DD1C433C9; Wed, 2 Aug 2023 15:58:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1690991910; bh=U3RyHVblo8oECYdzSIpQ83u0l7vnn+UTTimUbUNg+cc=; h=Date:To:From:Subject:From; b=Rj6dQaD1/vunVT9Tkm42TQqMhb74yWwlxwmSlLfjtZnbyDgMHVgo1QhVurQ0xbGoo IgpAxjCZeqjsrg6VC56Dnx/zNOB3bnwfGhxhzTPNi4dIutjurtd1c3dXshE5SzshK8 XdXCZsDsiw8h2regKJcovqSIUCahOTSVCbUEF/cM= Date: Wed, 02 Aug 2023 08:58:29 -0700 To: mm-commits@vger.kernel.org, zhengqi.arch@bytedance.com, yuzhao@google.com, surenb@google.com, suleiman@google.com, steven@liquorix.net, stable@vger.kernel.org, quic_charante@quicinc.com, oleksandr@natalenko.name, matthias.bgg@gmail.com, lecopzer.chen@mediatek.com, heftig@archlinux.org, bgeffon@google.com, baohua@kernel.org, angelogioacchino.delregno@collabora.com, aneesh.kumar@linux.ibm.com, kaleshsingh@google.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-unstable-multi-gen-lru-fix-per-zone-reclaim.patch added to mm-unstable branch Message-Id: <20230802155830.68DD1C433C9@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: Multi-gen LRU: Fix per-zone reclaim has been added to the -mm mm-unstable branch. Its filename is mm-unstable-multi-gen-lru-fix-per-zone-reclaim.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-unstable-multi-gen-lru-fix-per-zone-reclaim.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Kalesh Singh Subject: Multi-gen LRU: Fix per-zone reclaim Date: Tue, 1 Aug 2023 19:56:02 -0700 MGLRU has a LRU list for each zone for each type (anon/file) in each generation: long nr_pages[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES]; The min_seq (oldest generation) can progress independently for each type but the max_seq (youngest generation) is shared for both anon and file. This is to maintain a common frame of reference. In order for eviction to advance the min_seq of a type, all the per-zone lists in the oldest generation of that type must be empty. The eviction logic only considers pages from eligible zones for eviction or promotion. scan_folios() { ... for (zone = sc->reclaim_idx; zone >= 0; zone--) { ... sort_folio(); // Promote ... isolate_folio(); // Evict } ... } Consider the system has the movable zone configured and default 4 generations. The current state of the system is as shown below (only illustrating one type for simplicity): Type: ANON Zone DMA32 Normal Movable Device Gen 0 0 0 4GB 0 Gen 1 0 1GB 1MB 0 Gen 2 1MB 4GB 1MB 0 Gen 3 1MB 1MB 1MB 0 Now consider there is a GFP_KERNEL allocation request (eligible zone index <= Normal), evict_folios() will return without doing any work since there are no pages to scan in the eligible zones of the oldest generation. Reclaim won't make progress until triggered from a ZONE_MOVABLE allocation request; which may not happen soon if there is a lot of free memory in the movable zone. This can lead to OOM kills, although there is 1GB pages in the Normal zone of Gen 1 that we have not yet tried to reclaim. This issue is not seen in the conventional active/inactive LRU since there are no per-zone lists. If there are no (not enough) folios to scan in the eligible zones, move folios from ineligible zone (zone_index > reclaim_index) to the next generation. This allows for the progression of min_seq and reclaiming from the next generation (Gen 1). Qualcomm, Mediatek and raspberrypi [1] discovered this issue independently. [1] https://github.com/raspberrypi/linux/issues/5395 Link: https://lkml.kernel.org/r/20230802025606.346758-1-kaleshsingh@google.com Fixes: ac35a4902374 ("mm: multi-gen LRU: minimal implementation") Signed-off-by: Kalesh Singh Reported-by: Charan Teja Kalla Reported-by: Lecopzer Chen Tested-by: AngeloGioacchino Del Regno [mediatek] Tested-by: Charan Teja Kalla Cc: Yu Zhao Cc: Barry Song Cc: Brian Geffon Cc: Jan Alexander Steffens (heftig) Cc: Matthias Brugger Cc: Oleksandr Natalenko Cc: Qi Zheng Cc: Steven Barrett Cc: Suleiman Souhlal Cc: Suren Baghdasaryan Cc: Aneesh Kumar K V Cc: Signed-off-by: Andrew Morton --- mm/vmscan.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) --- a/mm/vmscan.c~mm-unstable-multi-gen-lru-fix-per-zone-reclaim +++ a/mm/vmscan.c @@ -4889,7 +4889,8 @@ static int lru_gen_memcg_seg(struct lruv * the eviction ******************************************************************************/ -static bool sort_folio(struct lruvec *lruvec, struct folio *folio, int tier_idx) +static bool sort_folio(struct lruvec *lruvec, struct folio *folio, struct scan_control *sc, + int tier_idx) { bool success; int gen = folio_lru_gen(folio); @@ -4939,6 +4940,13 @@ static bool sort_folio(struct lruvec *lr return true; } + /* ineligible */ + if (zone > sc->reclaim_idx) { + gen = folio_inc_gen(lruvec, folio, false); + list_move_tail(&folio->lru, &lrugen->folios[gen][type][zone]); + return true; + } + /* waiting for writeback */ if (folio_test_locked(folio) || folio_test_writeback(folio) || (type == LRU_GEN_FILE && folio_test_dirty(folio))) { @@ -4987,7 +4995,8 @@ static bool isolate_folio(struct lruvec static int scan_folios(struct lruvec *lruvec, struct scan_control *sc, int type, int tier, struct list_head *list) { - int gen, zone; + int i; + int gen; enum vm_event_item item; int sorted = 0; int scanned = 0; @@ -5003,9 +5012,10 @@ static int scan_folios(struct lruvec *lr gen = lru_gen_from_seq(lrugen->min_seq[type]); - for (zone = sc->reclaim_idx; zone >= 0; zone--) { + for (i = MAX_NR_ZONES; i > 0; i--) { LIST_HEAD(moved); int skipped = 0; + int zone = (sc->reclaim_idx + i) % MAX_NR_ZONES; struct list_head *head = &lrugen->folios[gen][type][zone]; while (!list_empty(head)) { @@ -5019,7 +5029,7 @@ static int scan_folios(struct lruvec *lr scanned += delta; - if (sort_folio(lruvec, folio, tier)) + if (sort_folio(lruvec, folio, sc, tier)) sorted += delta; else if (isolate_folio(lruvec, folio, sc)) { list_add(&folio->lru, list); _ Patches currently in -mm which might be from kaleshsingh@google.com are mm-unstable-multi-gen-lru-fix-per-zone-reclaim.patch mm-unstable-multi-gen-lru-avoid-race-in-inc_min_seq.patch mm-unstable-multi-gen-lru-fix-can_swap-in-lru_gen_look_around.patch