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 C8186111227A for ; Thu, 2 Apr 2026 03:02:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EC2FA6B0088; Wed, 1 Apr 2026 23:02:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E99DB6B0089; Wed, 1 Apr 2026 23:02:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DD6C46B008A; Wed, 1 Apr 2026 23:02:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id CE2996B0088 for ; Wed, 1 Apr 2026 23:02:57 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 6F02E160169 for ; Thu, 2 Apr 2026 03:02:57 +0000 (UTC) X-FDA: 84612118794.04.4646215 Received: from out-188.mta0.migadu.com (out-188.mta0.migadu.com [91.218.175.188]) by imf10.hostedemail.com (Postfix) with ESMTP id 24EAFC0008 for ; Thu, 2 Apr 2026 03:02:53 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=qAG3p++B; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf10.hostedemail.com: domain of shakeel.butt@linux.dev designates 91.218.175.188 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1775098975; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=+Bm/iZ2SZCt+AC99FFO20xgoljQ3GBYc4xpX0mliCyE=; b=7sBeXYoDCkgBJAsCMTNcXMyep1AZ+wKigEWqAYqqszQX2k/IoN396qESGph0U241a0QHz8 KSy5wUF1P6rVeIhdeK/nzRL9/HoGKgjotBL4dfnsHteLIENLIZ2wZBeAgZfhw8gtEgoYdb /1ARgZb6DzvutiRRIjWkVPUsyaN+Q5Y= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1775098975; a=rsa-sha256; cv=none; b=Qi7guNeOeZ/IdnP7ODs+YeE8a/WlWj4ZMb9ZJWxdgMRe/9wqgBZZPo6xk/RiTSk4gDhtlM 68bQCK/dS5W5sOU4dGeRutIkokpwatfgMwegcMAoFrVpI28kuKpGO+30TjqNHVBqyLnWpy 7AlkObq5bsMY54Vg8BaMFqRlsts5arU= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=qAG3p++B; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf10.hostedemail.com: domain of shakeel.butt@linux.dev designates 91.218.175.188 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev Date: Wed, 1 Apr 2026 20:02:44 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1775098968; 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: in-reply-to:in-reply-to:references:references; bh=+Bm/iZ2SZCt+AC99FFO20xgoljQ3GBYc4xpX0mliCyE=; b=qAG3p++Bsn93CJPXaIZuqnQ12F2PgI1xcdGvaWN9uz51Wg/uVQ+KMak2x006Ut5RGPdaEA 6rUxxQD1zapneZCktFQMnMPeqR6jhY599/Ohfe0J90Lup/dUWK7w6fyPdgaEjd6j2St2kH K0DDzCKAdWK3cGmrWYb3ayXGCBfAd/I= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Shakeel Butt To: "zhaoyang.huang" Cc: Andrew Morton , Michal Hocko , "T . J . Mercier" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Zhaoyang Huang , steve.kang@unisoc.com Subject: Re: [PATCHv3] mm: remove '!root_reclaim' checking in should_abort_scan() Message-ID: References: <20260318011558.1696310-1-zhaoyang.huang@unisoc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260318011558.1696310-1-zhaoyang.huang@unisoc.com> X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 24EAFC0008 X-Stat-Signature: 4heh86dnbq9164qb43radgh7ttmo64gc X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1775098973-136765 X-HE-Meta: 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 Rgs6TRMm 5HSmq7bWckTYNVoSU5lPQHGX0Ql4tidC4ott3iMW0wKJAPcKxa5ufKQI+Ooa413Opix8F3h6xZFB8q6YsUavEv0B5cFuxehwEukTKuQdxPfyMXs4KaKluPxvzcScBmzx2egqBy0XDWXvuB778CebaOqxrrWA+t/wxUX3jr4LWnVRH+Ro0LVc3FlCWp4Eh/ZrOqUYttVA0FTZgtkf1jsbvWW+4NPB/hWHdNq0wPW6vnC/wPo77loTpNxxBky4G8cb3LwcAaLdAivrhPfPtJ6DOuhpj45QaAEEKTJwBrWmIXU2/W0vC9BazrnHaDXc9kbNkYfgI2K04+mHVB0yS1cmHbiU/BOXrDchq7TNrgV/DnCeY5RzNZbGNJbd2ehTFJnw75LPk Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Mar 18, 2026 at 09:15:58AM +0800, zhaoyang.huang wrote: > From: Zhaoyang Huang > > Android systems usually use memory.reclaim interface to implement user > space memory management which expects that the requested reclaim target > and actually reclaimed amount memory are not diverging by too much. With > the current MGRLU implementation there is, however, no bail out when the > reclaim target is reached and this could lead to an excessive reclaim > that scales with the reclaim hierarchy size.For example, we can get a > nr_reclaimed=394/nr_to_reclaim=32 proactive reclaim under a common 1-N > cgroup hierarchy. > This defect arised from the goal of keeping fairness among memcgs that > is, for try_to_free_mem_cgroup_pages -> shrink_node_memcgs -> > shrink_lruvec -> lru_gen_shrink_lruvec -> try_to_shrink_lruvec, the > !root_reclaim(sc) check was there for reclaim fairness, which was > necessary before commit 'b82b530740b9' ("mm: vmscan: restore > incremental cgroup iteration") because the fairness depended on > attempted proportional reclaim from every memcg under the target > memcg. However after commit 'b82b530740b9' there is no longer a need > to visit every memcg to ensure fairness. Let's have try_to_shrink_lruvec > bail out when the nr_reclaimed achieved. > > Suggested-by: T.J.Mercier > Reviewed-by: T.J.Mercier > Signed-off-by: Zhaoyang Huang Acked-by: Shakeel Butt