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 C08083C73D7; Tue, 18 Aug 2026 05:38:24 +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=1787031504; cv=none; b=ad+bN3+rOtGUP/RmE5RF8R/KC11ecud07NjcEfo6oZkMY7WFcBdqt79PaGKJSkOTdDurFQiW6fm4P/EKmhC3Sy4fYjL18y8L5vJq1FaN2ss0WXg/ztjoFC0UzdbESsAI5fx9tSyxiBCE48/H8q+h+pD30mCs5wxK6AOekPCtHSE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787031504; c=relaxed/simple; bh=Sx8EIzWCQwmQ5nLlhTfCRcDmg7PW3HdfIWlqtAUVtug=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=bxgT1zObnrqBD1Q95mPkPkaRReaFrcQGLo69W8foOdJM4e+d8HIihzFA5i+dIEf3NRGDJvQPXlSkb4V0qV3+FFCO3oymnZquODylt8N7dRx5dwbkRMMF3ZTdxrNM/RmnbKB6kLU6kYyJlnkk9rGUlzC5AnkBY0QcgxrfR/YG4QI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kKAKg1hL; 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="kKAKg1hL" Received: by smtp.kernel.org (Postfix) with ESMTPS id 72091C4AF1A; Tue, 18 Aug 2026 05:38:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1787031504; bh=Sx8EIzWCQwmQ5nLlhTfCRcDmg7PW3HdfIWlqtAUVtug=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=kKAKg1hL8/QJ6S0wakilKwr0s1rR7LJsgNCNefhuFRVEv8PUwaWU9/SSo2PhnEhZn HVKQ9xn+0mBjwgJV4cWk66CGmEVELNGV4V7QqIzj4K95A/LY1fJixWtIBpIr04SrFf DBlbgwCurQ10l/B4NqBwnexoc8HLfHMwzuZ+B49662MrfentTkxYsUwdlYU7l2BzZa SnXLgolF2haIKbQz4jZvJttKu8WCYkfMSufzF+wQQhKdZjM82gQbnAc/t2D4jgB49A lT0pEkpbCsOUH5Wcwz0fwpdWc0Cqd2mUBsOITguRHS3xBi0rbG8F6iowhhHfiQ5WGJ EJeOrv0s/cWPg== 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 5A915C5DF67; Tue, 18 Aug 2026 05:38:24 +0000 (UTC) From: Kairui Song via B4 Relay Date: Tue, 18 Aug 2026 13:38:07 +0800 Subject: [PATCH 5/7] mm/mglru: use explicit tier range in read_ctrl_pos() 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: <20260818-mglru-flags-cleanup-v1-5-8dbbdac0d28c@tencent.com> References: <20260818-mglru-flags-cleanup-v1-0-8dbbdac0d28c@tencent.com> In-Reply-To: <20260818-mglru-flags-cleanup-v1-0-8dbbdac0d28c@tencent.com> To: linux-mm@kvack.org Cc: Andrew Morton , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Shakeel Butt , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Chris Li , Baolin Wang , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Yu Zhao , Zi Yan , Qi Zheng , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Kairui Song , Kairui Song X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1787031500; l=3448; i=kasong@tencent.com; s=kasong-sign-tencent; h=from:subject:message-id; bh=GYBGb1xTYAtwF8ULj9QKeuy7M/IFOhc3aBT9Nkjj2Us=; b=hZsipqcQnctqC9gaBUbfHO2y8v0AyYm5uSBYOqOLuZZpuIPS1tItIjOSQv7M5GcDMTYwSIrAD Vygm8AIFzatCFz7bA7FXXGfPRfwCpMJd9W58MsRsA4lbht1gCaM74wm 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 read_ctrl_pos() encodes the tier range in a single "tier" parameter via "tier % MAX_NR_TIERS" as the start and "min(tier, MAX_NR_TIERS-1)" as the end. This is hard to follow, maintain, or extend. Tier values 0..3 select a single tier, while tier == MAX_NR_TIERS selects the full range. Replace it with explicit (tier_min, tier_max) parameters using a closed [tier_min, tier_max] interval, and add LRU_TIER_MIN and LRU_TIER_MAX for the tier bounds. The call sites now become self-documenting: - get_tier_idx: (LRU_TIER_MIN, LRU_TIER_MIN) for the first tier, (tier, tier) for each subsequent tier - get_type_to_scan: (LRU_TIER_MIN, LRU_TIER_MAX) for the full range No functional change. Signed-off-by: Kairui Song --- include/linux/mmzone.h | 2 ++ mm/vmscan.c | 18 ++++++++++-------- 2 files changed, 12 insertions(+), 8 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 32d9354a754f..d0b5c6217d25 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -492,6 +492,8 @@ enum lruvec_flags { * folio->flags, masked by LRU_REFS_MASK. */ #define MAX_NR_TIERS 4U +#define LRU_TIER_MIN 0U +#define LRU_TIER_MAX (MAX_NR_TIERS - 1) #ifndef __GENERATING_BOUNDS_H diff --git a/mm/vmscan.c b/mm/vmscan.c index a819be6b7ae9..a613bb8d7271 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3198,8 +3198,8 @@ struct ctrl_pos { int gain; }; -static void read_ctrl_pos(struct lruvec *lruvec, int type, int tier, int gain, - struct ctrl_pos *pos) +static void read_ctrl_pos(struct lruvec *lruvec, int type, int tier_min, + int tier_max, int gain, struct ctrl_pos *pos) { int i; struct lru_gen_folio *lrugen = &lruvec->lrugen; @@ -3208,7 +3208,7 @@ static void read_ctrl_pos(struct lruvec *lruvec, int type, int tier, int gain, pos->gain = gain; pos->refaulted = pos->total = 0; - for (i = tier % MAX_NR_TIERS; i <= min(tier, MAX_NR_TIERS - 1); i++) { + for (i = tier_min; i <= tier_max; i++) { pos->refaulted += lrugen->avg_refaulted[type][i] + atomic_long_read(&lrugen->refaulted[hist][type][i]); pos->total += lrugen->avg_total[type][i] + @@ -4804,9 +4804,9 @@ static int get_tier_idx(struct lruvec *lruvec, int type) * This value is chosen because any other tier would have at least twice * as many refaults as the first tier. */ - read_ctrl_pos(lruvec, type, 0, 2, &sp); - for (tier = 1; tier < MAX_NR_TIERS; tier++) { - read_ctrl_pos(lruvec, type, tier, 3, &pv); + read_ctrl_pos(lruvec, type, LRU_TIER_MIN, LRU_TIER_MIN, 2, &sp); + for (tier = LRU_TIER_MIN + 1; tier <= LRU_TIER_MAX; tier++) { + read_ctrl_pos(lruvec, type, tier, tier, 3, &pv); if (!positive_ctrl_err(&sp, &pv)) break; } @@ -4827,8 +4827,10 @@ static int get_type_to_scan(struct lruvec *lruvec, int swappiness) * Compare the sum of all tiers of anon with that of file to determine * which type to scan. */ - read_ctrl_pos(lruvec, LRU_GEN_ANON, MAX_NR_TIERS, swappiness, &sp); - read_ctrl_pos(lruvec, LRU_GEN_FILE, MAX_NR_TIERS, MAX_SWAPPINESS - swappiness, &pv); + read_ctrl_pos(lruvec, LRU_GEN_ANON, LRU_TIER_MIN, LRU_TIER_MAX, + swappiness, &sp); + read_ctrl_pos(lruvec, LRU_GEN_FILE, LRU_TIER_MIN, LRU_TIER_MAX, + MAX_SWAPPINESS - swappiness, &pv); return positive_ctrl_err(&sp, &pv); } -- 2.55.0