From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794693548; b=BboP3GJGQkRikJJ4pIjDXB3AAGlNB+nWOqp1KZkDv2b4Jn2jNY+1u/pmf0htVnCDsfww RJUm/GQWlLxGdrrHJBQ1t2yNThpu/MCAUScIpNIoIMj8T5VNtV5AdLNIbcmX4+q78vJSg sqnIJctNHBPo4eWWh0/TlSkJ7XcweIT/q4xWbknto/XPCs2cJOT+r66eztv+ICOiGs2ZO rXpwD2sH3WnAERry+/hZz3Mt9E65lGyaahA/lXoxYo395tg4V06DtJsrC883sFbR7w7RR biSbwHv4tygRbsLv+wiooLE15v+FCcfRhCdPTpPddLgfQLxAL0uSquKvDaYqESOXq9A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794693548; h=Received:DKIM-Signature:Date:To:From:Subject:Message-Id; bh=TD6ND4bWADsdCF7eIz7aTytT5w4UHzYwaVwZnPScXU4=; b=eTqI+HJFfDh2pID3b4Pf0eglySPZylx5WH2r8Q8Isb+C+5CUSmhaUwXl6/WidH49Se8R iZUVTEaIk7XsVsnUIUa2Gz9mQtVdrvmAhNxFyrhupXxFs9/uaJJvpkcPSyOw/xON8TKFH BaTa1H+u4R2/zNXZaeT+DVpBmlBaZyC0d82WBxt2mQh9q0ER1PNVRv191dT9uUUGzjK50 E9c9DCEbVmpVwFNynjUNbmkQa/il/A2IBH0eAkczsGdeMInoes1PVIDQmm4iE81tjs/00 O87VXeHPWcs/cdK/+nGR3yncc5QUajzwXhK7gws3CvmULt0MEnjrpXitjHxB+y8W3KQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linux-foundation.org header.i=@linux-foundation.org header.a=rsa-sha256 header.s=korg header.b=qilQVFgM; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9C0F6606A329 for ; Sat, 14 Nov 2026 21:59:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.a=rsa-sha256 header.s=korg header.b=qilQVFgM Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3FCD31F000C4; Sat, 14 Nov 2026 21:59:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1794693548; bh=TD6ND4bWADsdCF7eIz7aTytT5w4UHzYwaVwZnPScXU4=; h=Date:To:From:Subject; b=qilQVFgMPkjhd2AKp7DBUqgZxKVOJ18mlFcmh36+eA/ZBo3W1jS2FpFYLYWrf2P+u JefaU9FanqSuEMhFjJuvbCeVSYtsttHdtJ4tJOxb9axY0xKMchet8dZkZefX+Tu4n/ TnuZ3ChPJ4PcIf+ycY+WarDwZh5f5rdrQHWLuO/w= Date: Sat, 14 Nov 2026 13:59:07 -0800 To: mm-commits@vger.kernel.org,kasong@tencent.com,akpm@linux-foundation.org From: Andrew Morton Subject: [to-be-updated] mm-mglru-lift-the-forced-protection-of-reclaimer.patch removed from -mm tree Message-Id: <20261114215908.3FCD31F000C4@smtp.kernel.org> X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list The quilt patch titled Subject: mm/mglru: lift the forced protection of reclaimer has been removed from the -mm tree. Its filename was mm-mglru-lift-the-forced-protection-of-reclaimer.patch This patch was dropped because an updated version will be issued ------------------------------------------------------ From: Kairui Song Subject: mm/mglru: lift the forced protection of reclaimer Date: Sat, 14 Nov 2026 02:55:29 +0800 When a type is drained down to MIN_NR_GENS gens, the reclaimer will fail to make any progress on that type without aging. However aging comes with a cost, and it will take time to finish. Even if we do aging more proactively, when under great pressure, gens will still be drained very fast so the new gens produced by aging can't catch up with the consumption. With MIN_NR_GENS setting blocking the reclaim, we will run into OOM. This OOM can be reproduced by the previous test program [1] used for fixing another aging problem [2]. When running in great pressure, certain workloads will keep seeing premature OOM with MGLRU, and never see any OOM with classical LRU. This might get worse if we implement async aging, or avoid hotness inversion in aging, as they will slow down the aging process even more. To fix this, let's first drop the get_nr_gens() == MIN_NR_GENS early return and let the raised-priority scan bound cover max_seq itself. Mapped folios will still survive as the rmap PTE check will keep them. Unmapped cache folios may thrashing more when under great pressure, which is really a problem that should be fixed with refault distance and frequecy aware promotoin instead [3]. Link: https://lore.kernel.org/20261113185541.70203-5-baohua@kernel.org Link: https://github.com/ryncsn/emm-test-project/tree/master/file-anon-mix-pressure [1] Link: https://lore.kernel.org/linux-mm/20260428-mglru-reclaim-v7-0-02fabb92dc43@tencent.com/ [2] Link: https://lore.kernel.org/linux-mm/20260502-mglru-fg-v1-0-913619b014d9@tencent.com/ [3] Signed-off-by: Kairui Song Signed-off-by: Barry Song (Xiaomi) Signed-off-by: Andrew Morton Reviewed-by: Kunwu Chan Cc: Axel Rasmussen Cc: Baolin Wang Cc: Baoquan He Cc: Johannes Weiner Cc: Cc: Liam R. Howlett Cc: wang lian Cc: Cc: Cc: Michal Hocko Cc: Qi Zheng Cc: Ridong Chen Cc: Mike Rapoport Cc: Kairui Song Cc: Shakeel Butt Cc: Suren Baghdasaryan Cc: wangzicheng Cc: Wei Xu Cc: Yuanchu Xie Cc: Bo Zhang Cc: Hui Zhu Cc: Siddharth Chintamaneni Cc: Kunwu Chan Cc: Bo Zhang --- mm/vmscan.c | 34 +++++++++++++++++++++++++--------- 1 file changed, 25 insertions(+), 9 deletions(-) --- a/mm/vmscan.c~mm-mglru-lift-the-forced-protection-of-reclaimer +++ a/mm/vmscan.c @@ -4677,7 +4677,7 @@ void lru_gen_reparent_memcg(struct mem_c ******************************************************************************/ static bool sort_folio(struct lruvec *lruvec, struct folio *folio, struct scan_control *sc, - int min_gen, int tier_idx) + int min_gen, int max_gen, int tier_idx) { int gen = folio_lru_gen(folio); int type = folio_is_file_lru(folio); @@ -4694,12 +4694,22 @@ static bool sort_folio(struct lruvec *lr if (!folio_evictable(folio)) return false; - /* promoted */ + /* promoted, or moved due to reparenting. */ if (gen != min_gen) { list_move(&folio->lru, &lrugen->folios[gen][type][zone]); return true; } + /* + * We are reclaiming the last gen left. Folios in this gen can no + * longer be promoted or protected, so just isolate them. The one + * exception is lru_gen_reparent_memcg(), which is handled above. + */ + if (min_gen == max_gen) { + VM_WARN_ON_ONCE(zone > sc->reclaim_idx); + return false; + } + /* protected */ if (tier > tier_idx || refs + workingset == BIT(LRU_REFS_WIDTH) + 1) { gen = folio_inc_gen(lruvec, folio, min_gen); @@ -4754,15 +4764,16 @@ static int scan_folios(unsigned long nr_ struct list_head *list, int *isolatedp) { int i; - int gen; enum node_stat_item item; int sorted = 0; int scanned = 0; int isolated = 0; int skipped = 0; + int gen, max_gen; unsigned long min_seq; unsigned long remaining = nr_to_scan; struct lru_gen_folio *lrugen = &lruvec->lrugen; + DEFINE_MAX_SEQ(lruvec); VM_WARN_ON_ONCE(nr_to_scan > MAX_LRU_BATCH); VM_WARN_ON_ONCE(!list_empty(list)); @@ -4775,18 +4786,24 @@ static int scan_folios(unsigned long nr_ if (sc->priority == DEF_PRIORITY) min_seq = lrugen->min_seq[type]; else - min_seq = lruvec_populated_min_seq(lruvec, type, lrugen->max_seq - MIN_NR_GENS + 1); - - if (get_nr_gens(lruvec, type) == MIN_NR_GENS) - return 0; + min_seq = lruvec_populated_min_seq(lruvec, type, lrugen->max_seq); gen = lru_gen_from_seq(min_seq); + max_gen = lru_gen_from_seq(max_seq); + for (i = MAX_NR_ZONES; i > 0; i--) { LIST_HEAD(moved); int skipped_zone = 0; int zone = (sc->reclaim_idx + i) % MAX_NR_ZONES; struct list_head *head = &lrugen->folios[gen][type][zone]; + /* + * If there is only one gen left, rotating the unreclaimable + * zone become meaningless, just skip them. + */ + if (gen == max_gen && zone > sc->reclaim_idx) + continue; + while (!list_empty(head)) { struct folio *folio = lru_to_folio(head); int delta = folio_nr_pages(folio); @@ -4797,8 +4814,7 @@ static int scan_folios(unsigned long nr_ VM_WARN_ON_ONCE_FOLIO(folio_zonenum(folio) != zone, folio); scanned += delta; - - if (sort_folio(lruvec, folio, sc, gen, tier)) + if (sort_folio(lruvec, folio, sc, gen, max_gen, tier)) sorted += delta; else if (isolate_folio(lruvec, folio, sc)) { list_add(&folio->lru, list); _ Patches currently in -mm which might be from kasong@tencent.com are mm-mglru-skip-zones-above-reclaim_idx-instead-of-rotating-them.patch mm-mglru-return-for-unavailable-anon-reclaim-earlier.patch mm-mglru-balance-anon-and-file-scan-budget-by-refault-rate.patch mm-mglru-lift-youngest-gen-protection-for-higher-priority.patch