From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A3292C4451B for ; Mon, 20 Jul 2026 02:49:30 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 78F176B008A; Sun, 19 Jul 2026 22:49:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 73FBC6B008C; Sun, 19 Jul 2026 22:49:29 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 654CD6B0092; Sun, 19 Jul 2026 22:49:29 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 3FE826B008A for ; Sun, 19 Jul 2026 22:49:29 -0400 (EDT) Received: from smtpin19.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id B4DF48073C for ; Mon, 20 Jul 2026 02:49:28 +0000 (UTC) X-FDA: 85007624016.19.BC2EAFC Received: from out-170.mta1.migadu.com (out-170.mta1.migadu.com [95.215.58.170]) by imf26.hostedemail.com (Postfix) with ESMTP id DD277140008 for ; Mon, 20 Jul 2026 02:49:26 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="tU9U/1Xc"; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf26.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.170 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1784515767; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=UieMaWjn37WtAKNVXeqODJ/nhyQJ2CNCH8qbQcNSy/k=; b=nukW6O49aPbwvtIOk3969QHol1AWtNPnXFZva+ND4fSgiPPRakQfsA8k2C46Sfz48OldyX Lma9TgQE7OQC8lynyUTimbIfiApQisYlLRRzKqEMIJF6E0YmXWH8HyQpqUWgcxQ9307s4q QPzCfIvhuBpE5vu3OGXjiS0FRIqp+mg= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="tU9U/1Xc"; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf26.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.170 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1784515767; b=BpdEsbaB7h2RzYBSqHxBcYvxFBJm5VibftLUIa+RMidQ7lPIc6Eix7wGuWBKXfB9MQOJBS erzpxhavyX38VXR5q/8h2YqfljMBjB2Y5XDSmjVfi6cxOt3s8T7fRfLd6PRMdxMZihWEEJ bKYNlvES4mAj52Cudk32cHrJ2iXPXPY= Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1784515765; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UieMaWjn37WtAKNVXeqODJ/nhyQJ2CNCH8qbQcNSy/k=; b=tU9U/1XcgGuRl/BZsM6szx+/SfKqjPtWrOEOswY01Srt4EvRzFDjuQMwhQJ+r0a1MpyQmU 3VqRuFqoXLf6VUpG/5Ypzb3BZKz1gEIj3LUS1K+y+ButvYzn1Nreyl+ePLt0EaLVeyLgrf iWjYjL6wtw3KHFcGOqwl7C3io2OtSfg= Date: Mon, 20 Jul 2026 10:48:56 +0800 MIME-Version: 1.0 Subject: Re: [PATCH v2 4/4] mm/mglru: fix anon-only reclaim evicting file pages when swappiness=max To: Barry Song , Ridong Chen Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, david@kernel.org, mhocko@kernel.org, shakeel.butt@linux.dev, ljs@kernel.org, kasong@tencent.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, hezhongkun.hzk@bytedance.com, muchun.song@linux.dev, dave@stgolabs.net, roman.gushchin@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ridong Chen References: <20260718095251.82937-1-ridong.chen@linux.dev> <20260718095251.82937-5-ridong.chen@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Qi Zheng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: DD277140008 X-Stat-Signature: dye1uadonhnnkzeu3iup9ngjsw8q3auy X-HE-Tag: 1784515766-854299 X-HE-Meta: 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 wLfAemKK I5DyNL8KFVMlXgBURgmKJiF/ID4+Eyi/zyxa2y9IrQX2rCXZ6oT87/YUOb9UQUpGxCxBSvAGeDpE7sekyltAQ6kMfSJY+QxfK5d30KXL9shVXOrLGN4QqrUeZqL/Nw//iKROiJyK2wzN05xvmvIciuL9W2lHrXN/UkAvhYLySyRbV3O77vNmLU15YqwZthg2mRkN0WLcqnwmlBalsk/t+jAklNIN3TWuSHynbkMq1Vq3ldRL01YoCAG1SlVhccF7XZddP6Znx7OzjoVlb7yJ+oPQZCuNidZNq01i9FJRe5X6PQqQu+Q48ZEQT6uVKaGW2Y2ip Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/18/26 9:43 PM, Barry Song wrote: > On Sat, Jul 18, 2026 at 5:54 PM Ridong Chen wrote: >> >> From: Ridong Chen >> >> The previous patch fixes this issue for the traditional LRU, which also >> exists in MGLRU [1]. Fix this by checking whether swappiness is >> SWAPPINESS_ANON_ONLY in get_swappiness() first, and returning 0 from >> get_nr_to_scan() when swappiness is SWAPPINESS_ANON_ONLY and anon pages >> cannot be reclaimed, to avoid useless work. > > Is this intended to avoid unnecessary work, or to prevent file folios > from being reclaimed incorrectly? Based on the test results below, it seems primarily intended to prevent file pages from being mistakenly reclaimed. Also, bailing out early in the SWAPPINESS_ANON_ONLY + !can_reclaim_anon_pages case is to avoid unnecessary work. Hi Ridong, perhaps the commit message could be clearer. ;) > >> >> The test result: >> Before fix: >> >> # cat /sys/kernel/mm/lru_gen/enabled >> 0x0007 >> # cat memory.stat >> anon 204800 >> file 67108864 >> ... >> pgsteal_proactive 0 >> pgscan_proactive 0 >> >> # echo "64M swappiness=max" > memory.reclaim >> # cat memory.stat >> anon 208896 >> file 0 >> ... >> pgsteal_proactive 16384 >> pgscan_proactive 16384 >> >> After fix: >> >> # cat memory.stat >> anon 188416 >> file 67215360 >> kernel 1970176 >> ... >> pgsteal_proactive 0 >> pgscan_proactive 0 >> >> # echo "64M swappiness=max" > memory.reclaim >> -bash: echo: write error: Resource temporarily unavailable >> # cat memory.stat >> anon 204800 >> file 67215360 >> ... >> pgsteal_proactive 0 >> pgscan_proactive 0 >> >> [1] https://sashiko.dev/#/patchset/20260717113300.214717-1-ridong.chen@linux.dev >> >> Fixes: 68a1436bde00 ("mm: add swappiness=max arg to memory.reclaim for only anon reclaim") >> Signed-off-by: Ridong Chen >> --- >> mm/vmscan.c | 14 +++++++++++++- >> 1 file changed, 13 insertions(+), 1 deletion(-) >> Overall, this looks good to me. Acked-by: Qi Zheng Thanks, Qi