From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 44B9856E073; Thu, 15 Oct 2026 18:15:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792088156; cv=none; b=bb64odZDVaTFC7QsM8ZPhhYiXNZquls7FH96nYTY7Y15UzF6JKWBDbXh2v/M8BFMznjtwFbxVPMIhiLl6mML7wjeNDeksSSDqLD+vktKpNrHihgpgnII78XFFPYE8ei5ksmvmWO26gfT4ml4bAvVmAr1fWnXm/k0Z/RiIJNF+2M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792088156; c=relaxed/simple; bh=U0XTsJ3+hlRGEX8wHc1IuMeoyed0jAtILmjU1NZvH7w=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=b0ZHYG9yWLPoZTs/6GFYPa+3gMcBxwZZOeAojuwAFwpHGerWMufqfisKW8Syhx5SEaF9ZNqvOikAdjlZ3COEcCnD5+AEUKc9yTvxYST1ruw8ztNbFw0yyaGVdAuYcl7VvmC3BuhoN1boAzwKqojCTzMQzDODodTi0oaCwwNnwDI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CV8B2hm7; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CV8B2hm7" Received: by smtp.kernel.org (Postfix) with ESMTPS id A7765C4AF13; Thu, 15 Oct 2026 18:15:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1792088155; bh=U0XTsJ3+hlRGEX8wHc1IuMeoyed0jAtILmjU1NZvH7w=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=CV8B2hm79IL3au/BRgJceXAVGFB0b7K12Rr/NWqEyNnbXX7amjLfdm0wluVSsFgRF WborxfzNSPU0rmjfSIWbHFPm8OK1nC7jDJDNiz2+ipusnLqOPJzOHNpxdTfZrjfDE3 QFRiOPkJDhbdbSkosH526nz7dxALeVQudDkxv6FzWHJ8nkNXUxeoXZnJLfTnvi9ZbK NwxsO33cRf0ekSetDlPycUKFfGV8L7ifiuaCHjefZ+DJOd/K5MgOQk9YKTAq6Qd0ww ZRSKfCO5DSbv6EfJU5uoOLGAdznGii+X0XmtN9KGamYSDj0f+nLhBh15UXyGnYw6Nm wR7PrHqHy4/Zg== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 90207CCA465; Thu, 15 Oct 2026 18:15:55 +0000 (UTC) From: Kairui Song via B4 Relay Date: Fri, 16 Oct 2026 02:15:56 +0800 Subject: [PATCH v4 07/17] mm/mglru, gup: mark folios referenced via a fast helper Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261016-mglru-fg-v4-7-2106750c0bfa@tencent.com> References: <20261016-mglru-fg-v4-0-2106750c0bfa@tencent.com> In-Reply-To: <20261016-mglru-fg-v4-0-2106750c0bfa@tencent.com> To: linux-mm@kvack.org, "Liam R. Howlett" , SJ Park Cc: Andrew Morton , Johannes Weiner , Muchun Song , Qi Zheng , Ying Huang , Chris Li , Baoquan He , Nico Pache , Usama Arif , Michal Hocko , Roman Gushchin , Shakeel Butt , David Hildenbrand , Lorenzo Stoakes , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Vlastimil Babka , Suren Baghdasaryan , Kemeng Shi , Nhat Pham , Youngjun Park , Zi Yan , Gregory Price , "Matthew Wilcox (Oracle)" , Baolin Wang , Ryan Roberts , Dev Jain , Lance Yang , Hugh Dickins , David Rientjes , Yu Zhao , Vernon Yang , Zicheng Wang , Chen Ridong , Tal Zussman , Kairui Song , Xiang Liu , Ehab Ababneh , zhaozhengzhuo , Lian Wang , Kunwu Chan , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, damon@lists.linux.dev, Kairui Song X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1792088152; l=2648; i=kasong@tencent.com; s=kasong-sign-tencent; h=from:subject:message-id; bh=ITEZgO0dikHo93wyt9sJ147BaR3AkKEeJae1nLOf4S8=; b=m7t9PG61hS7nPGevrgY2lLxFygT2BRwOkANXUPK9pgm7cjzydaFuFNGer2+HyT8kYNrOODT8f JQDjMBv3q9CBhHyCf1aD5G9FDxDU4iLASn7H87eMqcXifIm9Voax7yj X-Developer-Key: i=kasong@tencent.com; a=ed25519; pk=kCdoBuwrYph+KrkJnrr7Sm1pwwhGDdZKcKrqiK8Y1mI= X-Endpoint-Received: by B4 Relay for kasong@tencent.com/kasong-sign-tencent with auth_id=562 X-Original-From: Kairui Song Reply-To: kasong@tencent.com From: Kairui Song Introduce folio_inc_lru_refs_fast(): raise refs from 0 to LRU_REFS_REFERENCED via cmpxchg, or just set PG_referenced for the classical LRU as before. No counter update, promotion, and guarteens no other complex operations in following commits. Convert the gup fast-path sites. No behavior change for classical LRU. Tested-by: zhaozhengzhuo Signed-off-by: Kairui Song --- include/linux/mm_inline.h | 25 +++++++++++++++++++++++++ mm/gup.c | 6 +++--- 2 files changed, 28 insertions(+), 3 deletions(-) diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index 65415eeac802..effa13c63632 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -454,6 +454,31 @@ static inline bool lru_gen_del_folio(struct lruvec *lruvec, struct folio *folio, } #endif /* CONFIG_LRU_GEN */ +/** + * folio_inc_lru_refs_fast - Bump folio refs count without promotion. + * @folio: the folio + * + * Raise refs from 0 to LRU_REFS_REFERENCED and leave hotter folios + * untouched. For the classical LRU, a plain PG_referenced set. + */ +static __always_inline void folio_inc_lru_refs_fast(struct folio *folio) +{ + unsigned long new_flags, old_flags; + + if (!lru_gen_enabled()) { + folio_set_referenced(folio); + return; + } + + old_flags = READ_ONCE(*folio_flags(folio, 0)); + do { + if (lru_get_refs_flags(old_flags)) + break; + new_flags = old_flags; + lru_set_refs_flags(&new_flags, LRU_REFS_REFERENCED); + } while (!try_cmpxchg(folio_flags(folio, 0), &old_flags, new_flags)); +} + static __always_inline void lruvec_add_folio(struct lruvec *lruvec, struct folio *folio) { diff --git a/mm/gup.c b/mm/gup.c index f166acf794e3..b3f563d41192 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2896,7 +2896,7 @@ static unsigned long gup_fast_pte_range(pmd_t pmd, pmd_t *pmdp, gup_put_folio(folio, 1, flags); goto pte_unmap; } - folio_set_referenced(folio); + folio_inc_lru_refs_fast(folio); pages[nr_pages] = page; nr_pages++; } while (ptep++, addr += PAGE_SIZE, addr != end); @@ -2965,7 +2965,7 @@ static unsigned long gup_fast_pmd_leaf(pmd_t orig, pmd_t *pmdp, for (i = 0; i < nr_pages; i++) *(pages++) = page++; - folio_set_referenced(folio); + folio_inc_lru_refs_fast(folio); return nr_pages; } @@ -3007,7 +3007,7 @@ static unsigned long gup_fast_pud_leaf(pud_t orig, pud_t *pudp, for (i = 0; i < nr_pages; i++) *(pages++) = page++; - folio_set_referenced(folio); + folio_inc_lru_refs_fast(folio); return nr_pages; } -- 2.56.0