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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-66fb47a8b8fsm12141411d50.2.2026.09.09.02.42.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Sep 2026 02:42:14 -0700 (PDT) Date: Wed, 9 Sep 2026 02:42:10 -0700 (PDT) From: Hugh Dickins To: Andrew Morton cc: Ackerley Tng , Alexander Viro , Alexandre Ghiti , Baolin Wang , Barry Song , Binbin Wu , Christian Brauner , Christoph Hellwig , Christoph Lameter , Claudio Imbrenda , David Hildenbrand , JP Kobryn , Jan Kara , Jens Axboe , Johannes Weiner , Kairui Song , Kiryl Shutsemau , Lance Yang , Leonardo Bras , Lorenzo Stoakes , Marcelo Tosatti , Matthew Wilcox , Mel Gorman , Miaohe Lin , Michal Hocko , Minchan Kim , Muchun Song , Oscar Salvador , Peter Zijlstra , Qi Zheng , Rik van Riel , Sebastian Andrzej Siewior , Shakeel Butt , Suren Baghdasaryan , Vlastimil Babka , Yang Shi , Yu Zhao , Zach O'Keefe , Zi Yan , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2 01/26] mm/fbatch: remove !CONFIG_SMP special case of folio_activate() In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Stat-Signature: wsocgthgh611agfuotejfzsu1483irih X-Rspam-User: X-Rspamd-Queue-Id: 16C3C180004 X-Rspamd-Server: rspam03 X-HE-Tag: 1788946936-496694 X-HE-Meta: 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 ThvjWV3B 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 3.0 commit eb709b0d062e ("mm: batch activate_page() to reduce lock contention") brought in an ifdef CONFIG_SMP around activate batching: https://lore.kernel.org/linux-mm/20100805140755.501af8a7.akpm@linux-foundation.org/ shows a sensitivity to bloat that day, not any incompatibility with UP. No other batching here has a UP alternative, and it's a bit confusing: simplify mm/folio.c a little by removing it now. Certainly we can reduce UP bloat (and/or 32-bit bloat) by, say, lowering FOLIO_BATCH_SIZE from 31: traditionally 16, 14, 15, then raised to 31 by 6.9 commit 9cecde80aae0 ("mm: increase folio batch size"); or by giving just the static per-cpu folio batches a type of their own with a smaller array size on UP (1? or a little batching worthwhile even on UP?). But not right now, it's orthogonal to this series. And I suspect that the old ifdef led to lru_activate being placed last, whereas it's usually the second most popular fbatch: move it there, to match cpu_needs_drain() comment "Check these in order of likelihood that they're not zero". Signed-off-by: Hugh Dickins Acked-by: David Hildenbrand (Arm) Reviewed-By: Vlastimil Babka (SUSE) --- mm/folio.c | 40 ++++++---------------------------------- 1 file changed, 6 insertions(+), 34 deletions(-) diff --git a/mm/folio.c b/mm/folio.c index 50a6dbe55998..c093ca900a3e 100644 --- a/mm/folio.c +++ b/mm/folio.c @@ -48,12 +48,10 @@ struct cpu_fbatches { */ local_lock_t lock; struct folio_batch lru_add; + struct folio_batch lru_activate; struct folio_batch lru_deactivate_file; struct folio_batch lru_deactivate; struct folio_batch lru_lazyfree; -#ifdef CONFIG_SMP - struct folio_batch lru_activate; -#endif /* Protecting the following batches which require disabling interrupts */ local_lock_t lock_irq; struct folio_batch lru_move_tail; @@ -283,15 +281,6 @@ static void lru_activate(struct lruvec *lruvec, struct folio *folio) count_memcg_events(lruvec_memcg(lruvec), PGACTIVATE, nr_pages); } -#ifdef CONFIG_SMP -static void folio_activate_drain(int cpu) -{ - struct folio_batch *fbatch = &per_cpu(cpu_fbatches.lru_activate, cpu); - - if (folio_batch_count(fbatch)) - folio_batch_move_lru(fbatch, lru_activate); -} - void folio_activate(struct folio *folio) { if (folio_test_active(folio) || folio_test_unevictable(folio) || @@ -301,25 +290,6 @@ void folio_activate(struct folio *folio) folio_batch_add_and_move(folio, lru_activate); } -#else -static inline void folio_activate_drain(int cpu) -{ -} - -void folio_activate(struct folio *folio) -{ - struct lruvec *lruvec; - - if (!folio_test_clear_lru(folio)) - return; - - lruvec = folio_lruvec_lock_irq(folio); - lru_activate(lruvec, folio); - lruvec_unlock_irq(lruvec); - folio_set_lru(folio); -} -#endif - static void __lru_cache_activate_folio(struct folio *folio) { struct folio_batch *fbatch; @@ -628,6 +598,10 @@ void lru_add_drain_cpu(int cpu) trace_mm_lru_add_drain_tp(cpu, nr_folios); } + fbatch = &fbatches->lru_activate; + if (folio_batch_count(fbatch)) + folio_batch_move_lru(fbatch, lru_activate); + fbatch = &fbatches->lru_move_tail; /* Disabling interrupts below acts as a compiler barrier. */ if (data_race(folio_batch_count(fbatch))) { @@ -650,8 +624,6 @@ void lru_add_drain_cpu(int cpu) fbatch = &fbatches->lru_lazyfree; if (folio_batch_count(fbatch)) folio_batch_move_lru(fbatch, lru_lazyfree); - - folio_activate_drain(cpu); } /** @@ -759,11 +731,11 @@ static bool cpu_needs_drain(unsigned int cpu) /* Check these in order of likelihood that they're not zero */ return data_race(folio_batch_count(&fbatches->lru_add) || + folio_batch_count(&fbatches->lru_activate) || folio_batch_count(&fbatches->lru_move_tail) || folio_batch_count(&fbatches->lru_deactivate_file) || folio_batch_count(&fbatches->lru_deactivate) || folio_batch_count(&fbatches->lru_lazyfree) || - folio_batch_count(&fbatches->lru_activate) || need_mlock_drain(cpu)) || has_bh_in_lru(cpu, NULL); } -- 2.51.0