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=1794693556; b=CHKo6ElD681wf/PSCYnbnxJ1K7CExW6q3HmBNnRVpuAXcIKjbQ3s1to1RMxEIVHSE+Pp 2ZC4rU5eoWwPsBmaglEU6BFf9zCr9/eg6f00o8VH67eWN4NwP27+7Lz0Ip+Q4jhkeVd5l Ufme3NmH8Z/CjZAQjbWqgQuKkUCZn7XLsM/nSqxnl6KWgqA75Tqq8z7GFu/sbA6a6FQbV Besygx8AqqpMzdWoepdTvplcrFaWoC25SIPT5mA+BFF/VExOTGa+aUUYxOh9ikj/OnaF1 KxW8jxnisVNcXLGEJSFAaUbI3rtC5LarihOLi0dbFfqkJBTmP9cVG4Av0Fcr90L5aaA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794693556; h=Received:DKIM-Signature:Date:To:From:Subject:Message-Id; bh=KqgOrtNPDZiLTeQ66Os7KSP10pU5q7Mo76X8d2qBoyc=; b=J/Ci8CN6rRunDvNGS37MkseT3eq6zW7R6or7XhmDnKrx6xK1dgAO2mZTnRmIenTEHp9e immv3johooy04zFiJ4vGiraT8vWi54v3jY/BT+2fMQdp6V2v6UURLab1rQU2qM1DIpXZ2 NSc1JdWnHMq4FbEtsMaR/Xi4krzNOEGhP8ZnDWbYf/PheDgUg3ZjJNlkb/tS4ChHcMKYf 4rGeZe197NmCPp6KMvBwLyLRHodlAgBVFn6a78CWW0jllZcZutsFu93ywfGRQDoVRU9px IZa3BxK2T0arRLV3J17uKyKWRNhcd3IYx0APDgGmMk5/Zo49kBZrgno97P5BLMOSU0Q== 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=IYzNJKzL; 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 C0306606A329 for ; Sat, 14 Nov 2026 21:59:16 +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=IYzNJKzL Received: by smtp.kernel.org (Postfix) with ESMTPSA id 09C071F000C4; Sat, 14 Nov 2026 21:59:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1794693556; bh=KqgOrtNPDZiLTeQ66Os7KSP10pU5q7Mo76X8d2qBoyc=; h=Date:To:From:Subject; b=IYzNJKzLaOuy07boJW0PCHFU8Jq75WQGB9YDU82GyUwUm9nWr2IYNjXSXGpKZCJkj A0EWqRN4pU9aMoIdqr9YcDrobT2/S8xd7eoroOAf7lfGE1wpDquTmK68smTe/pVdFL oebB4DfQg3S0luvPoBNcYBrUQMRIensl10/SUHvs= Date: Sat, 14 Nov 2026 13:59:15 -0800 To: mm-commits@vger.kernel.org,baohua@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: [to-be-updated] mm-mglru-avoid-placing-rejected-folios-below-populated-gen.patch removed from -mm tree Message-Id: <20261114215916.09C071F000C4@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: avoid placing rejected folios below populated gen has been removed from the -mm tree. Its filename was mm-mglru-avoid-placing-rejected-folios-below-populated-gen.patch This patch was dropped because an updated version will be issued ------------------------------------------------------ From: "Barry Song (Xiaomi)" Subject: mm/mglru: avoid placing rejected folios below populated gen Date: Sat, 14 Nov 2026 02:55:34 +0800 We used to scan only the oldest generation in scan_folios(). In evict_folios(), we checked whether lru_gen_folio_seq(lruvec, folio, false) == min_seq[type]. If so, the folio was marked active and moved to younger generations. This was itself buggy, as folios in generation min_seq[type] - 1 would not be marked active by folio_set_active(), potentially causing a cold/hot inversion. Besides this issue, the old approach also differs from the current behavior, where we can scan fewer than two generations. Now that we can scan younger generations, including the youngest generation, this no longer prevents rejected folios from being placed in a generation below or at the populated generation. Such rejected folios would then be scanned again and again, resulting in extremely low `pg_steal/pg_scan` ratios. For example: pgsteal_file: 2312605 pgscan_file: 36465693 reclamation efficiency: 6.34% We pass `scanned_seq` to `move_folios_to_lru()` and make sure we either promote the folio or place it in the youngest generation when the populated generation is already the youngest one. Also, folio_set_active() is no longer needed. With this change, the results become: pgsteal_file: 2683815 pgscan_file: 4224244 reclamation efficiency: 63.53% The sys time for building the kernel also decreased from 4m30.532s to 3m50.188s while swappiness==1. Link: https://lore.kernel.org/20261113185541.70203-10-baohua@kernel.org 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: Kairui Song Cc: Liam R. Howlett Cc: wang lian Cc: Cc: Cc: Michal Hocko Cc: Qi Zheng Cc: Ridong Chen Cc: Mike Rapoport 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 --- include/linux/mm_inline.h | 22 +++++++++++++++++++++- mm/vmscan.c | 24 ++++++++++++------------ 2 files changed, 33 insertions(+), 13 deletions(-) --- a/include/linux/mm_inline.h~mm-mglru-avoid-placing-rejected-folios-below-populated-gen +++ a/include/linux/mm_inline.h @@ -332,7 +332,8 @@ static inline unsigned long lru_gen_foli return max(READ_ONCE(lrugen->max_seq) - gen + 1, READ_ONCE(lrugen->min_seq[type])); } -static inline bool lru_gen_add_folio(struct lruvec *lruvec, struct folio *folio, bool reclaiming) +static inline bool __lru_gen_add_folio(struct lruvec *lruvec, struct folio *folio, + unsigned long scanned_seq, bool reclaiming) { unsigned long seq; unsigned long flags; @@ -347,6 +348,8 @@ static inline bool lru_gen_add_folio(str return false; seq = lru_gen_folio_seq(lruvec, folio, reclaiming); + if (scanned_seq != -1UL) + seq = max(seq, min(scanned_seq + 1, lrugen->max_seq)); gen = lru_gen_from_seq(seq); flags = (gen + 1UL) << LRU_GEN_PGOFF; /* see the comment on MIN_NR_GENS about PG_active */ @@ -362,6 +365,17 @@ static inline bool lru_gen_add_folio(str return true; } +static inline bool lru_gen_add_folio(struct lruvec *lruvec, struct folio *folio, bool reclaiming) +{ + return __lru_gen_add_folio(lruvec, folio, -1UL, reclaiming); +} + +static inline bool lru_gen_add_rejected_folio(struct lruvec *lruvec, struct folio *folio, + unsigned long scanned_seq) +{ + return __lru_gen_add_folio(lruvec, folio, scanned_seq, false); +} + static inline bool lru_gen_del_folio(struct lruvec *lruvec, struct folio *folio, bool reclaiming) { unsigned long flags; @@ -419,6 +433,12 @@ static inline bool lru_gen_add_folio(str { return false; } + +static inline bool lru_gen_add_rejected_folio(struct lruvec *lruvec, struct folio *folio, + unsigned long scanned_seq) +{ + return false; +} static inline bool lru_gen_del_folio(struct lruvec *lruvec, struct folio *folio, bool reclaiming) { --- a/mm/vmscan.c~mm-mglru-avoid-placing-rejected-folios-below-populated-gen +++ a/mm/vmscan.c @@ -1865,7 +1865,8 @@ static bool too_many_isolated(struct pgl * * Note: The caller must not hold any lruvec lock. */ -static unsigned int move_folios_to_lru(struct list_head *list, bool do_rotate) +static unsigned int move_folios_to_lru(struct list_head *list, unsigned long seq, + bool do_rotate) { int nr_pages, nr_moved = 0; struct lruvec *lruvec = NULL; @@ -1922,7 +1923,7 @@ static unsigned int move_folios_to_lru(s !folio_test_referenced(folio) && folio_ref_count(folio) == folio_expected_ref_count(folio)) lruvec_add_folio_tail(lruvec, folio); - else + else if (seq == -1UL || !lru_gen_add_rejected_folio(lruvec, folio, seq)) lruvec_add_folio(lruvec, folio); nr_pages = folio_nr_pages(folio); @@ -2041,7 +2042,7 @@ static unsigned long shrink_inactive_lis nr_reclaimed = shrink_folio_list(&folio_list, pgdat, sc, &stat, false, lruvec_memcg(lruvec)); - move_folios_to_lru(&folio_list, true); + move_folios_to_lru(&folio_list, -1UL, true); mod_lruvec_state(lruvec, PGDEMOTE_KSWAPD + reclaimer_offset(sc), stat.nr_demoted); @@ -2152,8 +2153,8 @@ static void shrink_active_list(unsigned /* * Move folios back to the lru list. */ - nr_activate = move_folios_to_lru(&l_active, false); - nr_deactivate = move_folios_to_lru(&l_inactive, false); + nr_activate = move_folios_to_lru(&l_active, -1UL, false); + nr_deactivate = move_folios_to_lru(&l_inactive, -1UL, false); count_vm_events(PGDEACTIVATE, nr_deactivate); count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, nr_deactivate); @@ -4753,7 +4754,8 @@ static bool isolate_folio(struct lruvec static int scan_folios(unsigned long nr_to_scan, struct lruvec *lruvec, struct scan_control *sc, int type, int tier, - struct list_head *list, int *isolatedp) + struct list_head *list, int *isolatedp, + unsigned long *scanned_seq) { enum node_stat_item item; int zone_idx; @@ -4784,6 +4786,7 @@ static int scan_folios(unsigned long nr_ seq = lrugen->max_seq; seq = lruvec_populated_min_seq(lruvec, type, sc->reclaim_idx + 1, seq); + *scanned_seq = seq; gen = lru_gen_from_seq(seq); max_gen = lru_gen_from_seq(max_seq); @@ -4980,6 +4983,7 @@ static int evict_folios(unsigned long nr int tier, scanned, reclaimed; int isolated = 0, nr_isolated = 0; unsigned long total_reclaimed = 0; + unsigned long scanned_seq; bool skip_retry = false; struct mem_cgroup *memcg = lruvec_memcg(lruvec); struct pglist_data *pgdat = lruvec_pgdat(lruvec); @@ -4991,7 +4995,7 @@ static int evict_folios(unsigned long nr tier = get_tier_idx(lruvec, type); scanned = scan_folios(nr_to_scan, lruvec, sc, - type, tier, &list, &isolated); + type, tier, &list, &isolated, &scanned_seq); nr_isolated = isolated; if (nr_isolated) __mod_node_page_state(pgdat, NR_ISOLATED_ANON + type, @@ -5017,8 +5021,6 @@ retry: type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON); list_for_each_entry_safe_reverse(folio, next, &list, lru) { - DEFINE_MIN_SEQ(lruvec); - /* move_folios_to_lru() culls unevictable folios via folio_putback_lru() */ if (!folio_evictable(folio)) continue; @@ -5037,11 +5039,9 @@ retry: * so this effectively promotes them by at least one generation. */ folio_set_lru_refs(folio, 0); - if (lru_gen_folio_seq(lruvec, folio, false) == min_seq[type]) - folio_set_active(folio); } - move_folios_to_lru(&list, false); + move_folios_to_lru(&list, scanned_seq, false); walk = current->reclaim_state->mm_walk; if (walk && walk->batched) { _ Patches currently in -mm which might be from baohua@kernel.org are arm64-vmalloc-allow-arch_vmap_pte_range_map_size-to-batch-multiple-cont_pte.patch mm-vmalloc-extend-page-table-walk-to-support-larger-page_shift-sizes-and-eliminate-page-table-rewalk.patch mm-vmalloc-map-contiguous-pages-in-batches-for-vmap-if-possible.patch mm-vmalloc-align-vm_area-so-vmap-can-batch-mappings.patch mm-mglru-run-aging-when-one-type-has-no-populatable-folios.patch mm-mglru-restrict-eviction-accounting-to-eligible-zones.patch mm-mglru-reduce-lru-lock-contention-by-shrinking-folio-batches-in-inc_min_seq.patch mm-mglru-make-swappiness=1-file-reclaim-more-aggressive.patch