From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 F31423D9DBF for ; Fri, 31 Jul 2026 08:39:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785487154; cv=none; b=OhlZj2V7R5nxs/wS0adHiO+KP6VyMU79GSqKYzywpQTzbTPGtY+iWLneW3KB+GFcpKc8Csf1ryI2Hcikq4OSl1rdvuwSiXOEq1/jmxWs/ZVA8ohVVMz1Qba6VDMrjJnhWyyqhk1wZArl2LV28Ve1wqkioNuqCE2FXvPCu1Au3Qw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785487154; c=relaxed/simple; bh=qJM6K3gfhp9lqgQ1bjrKznW2mi5DScFFjm/436rkddk=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=u+MyQtyzMPxZoxJFBgF9RaY5XxLAVHAudjQJcz7ZW7FMJAUgYz7yAD/pr0801y6/rc+9UVq0nVgUM+t5O+nCu6PCeq/tcLepnXxPo3e+BWpR60Qp5OL10OJi2o5ush9LDQslFTn5WVnQEaxFZUbtC9jW2c18t5oT9JdOA6yqdak= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MRUp7+N8; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MRUp7+N8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 778D31F00A3A; Fri, 31 Jul 2026 08:39:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785487152; bh=YV+vGlkWwAAqTC1IWyggngTy7GK63iEPW6UUQSpPO7o=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=MRUp7+N8XwNJdsu5G0MjXW8uZSR7JgKcxsOQe35smP5Ce/TgkBCUhrkLBy5roxTwX wsNkeHlivzLYQ8qDRhUw8i5Ah+2z2t8t+3fF2yPrsBWMhPosqSaMQXlIZHNrjHltjD HNp9iOUMD9bPFzOx5ApnpLUBmkHv3dwvZlEI43vunfEqC+mlnIfF6Gij6+G8Sh+/iD 2hhEPoC2hKyKC2XbPDfwtErhBYGsFGyhYoe/MNMPYl0tUto6xJV77kQJWB+C/uNAAv 6vOmIvJs6DAdvL8rp9qpdP8/V6fYwsjx5HVqQWkZpydRCjGk8fcQsma3njfqqS1mm3 GJVPgIVmCADXw== From: "Barry Song (Xiaomi)" To: akpm@linux-foundation.org, linux-mm@kvack.org Cc: axelrasmussen@google.com, david@kernel.org, hannes@cmpxchg.org, kasong@tencent.com, linux-kernel@vger.kernel.org, ljs@kernel.org, lyugaofei@xiaomi.com, mhocko@kernel.org, qi.zheng@linux.dev, shakeel.butt@linux.dev, stevensd@chromium.org, weixugc@google.com, yuanchu@google.com, chenridong@xiaomi.com, zhangbo56@xiaomi.com, wangzicheng@honor.com, lianux.mm@gmail.com, Barry Song Subject: [RFC PATCH v3 3/6] mm/mglru: improve readability of isolate_folios() Date: Fri, 31 Jul 2026 16:38:40 +0800 Message-Id: <20260731083843.37811-4-baohua@kernel.org> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20260731083843.37811-1-baohua@kernel.org> References: <20260731083843.37811-1-baohua@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Ridong Chen The for_each_evictable_type() loop in isolate_folios() is misleading: it does not actually iterate over each evictable type. Instead, get_type_to_scan() selects the type to scan, while the iterator `i` merely bounds the number of attempts. Signed-off-by: Ridong Chen Co-developed-by: Barry Song (Xiaomi) Signed-off-by: Barry Song (Xiaomi) --- mm/vmscan.c | 47 +++++++++++++++++++++++++++-------------------- 1 file changed, 27 insertions(+), 20 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 31947fa60f18..0038f33aa318 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4828,35 +4828,42 @@ static int get_type_to_scan(struct lruvec *lruvec, int swappiness) return positive_ctrl_err(&sp, &pv); } +static inline bool is_single_type_reclaim(int swappiness) +{ + return swappiness == MIN_SWAPPINESS || + swappiness == SWAPPINESS_ANON_ONLY; +} + static int isolate_folios(unsigned long nr_to_scan, struct lruvec *lruvec, struct scan_control *sc, int swappiness, struct list_head *list, int *isolated, int *isolate_type, int *isolate_scanned) { - int i; - int total_scanned = 0; + bool single_type = is_single_type_reclaim(swappiness); int type = get_type_to_scan(lruvec, swappiness); + int total_scanned = 0, scanned, tier; + bool tried = false; - for_each_evictable_type(i, swappiness) { - int scanned; - int tier = get_tier_idx(lruvec, type); +retry: + tier = get_tier_idx(lruvec, type); + scanned = scan_folios(nr_to_scan, lruvec, sc, + type, tier, list, isolated); - scanned = scan_folios(nr_to_scan, lruvec, sc, - type, tier, list, isolated); + total_scanned += scanned; + if (*isolated) { + *isolate_type = type; + *isolate_scanned = scanned; + return total_scanned; + } - total_scanned += scanned; - if (*isolated) { - *isolate_type = type; - *isolate_scanned = scanned; - break; - } - /* - * If scanned > 0 and isolated == 0, avoid falling back to the - * other type, as this type remains sufficient. Falling back - * too readily can disrupt the positive_ctrl_err() bias. - */ - if (!scanned) - type = !type; + /* + * We are running out of the current reclaim type. Fall back to + * the other type if allowed. + */ + if (!tried && !scanned && !single_type) { + type = !type; + tried = true; + goto retry; } return total_scanned; -- 2.34.1