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[109.81.21.195]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43b4389321csm12045529f8f.29.2026.03.16.13.02.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Mar 2026 13:02:39 -0700 (PDT) Date: Mon, 16 Mar 2026 21:02:38 +0100 From: Michal Hocko To: "zhaoyang.huang" Cc: Andrew Morton , Yu Zhao , Rik van Riel , Shakeel Butt , Roman Gushchin , Johannes Weiner , "T . J . Mercier" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Zhaoyang Huang , steve.kang@unisoc.com Subject: Re: [PATCH] mm: remove '!root_reclaim' checking in should_abort_scan() Message-ID: References: <20260212032111.408865-1-zhaoyang.huang@unisoc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260212032111.408865-1-zhaoyang.huang@unisoc.com> X-HE-Meta: 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 4WYKefhy tBkROsntiFjhkYhJds950BywgFFrbUV2OC8TtVruE1gySQx8hyWKPWdVM9kFehUdmKFfq7akXtHnEYKF0OPeVHsOvQ9mDpARV/4K+OaE1bJ4TE7LWZu/oEoqonksAPEO/fs1gmbX80aUST/AJcxEct7ofw3JzvNdono15SvobESR1EdIT+Hsbxvk2p6r20rhfpr4zKNzHMBprgSHygiuMh3OVDabTp7QEM+ViGPe9Eq2Jo+I= X-Rspamd-Queue-Id: 1C10010000B X-Stat-Signature: nzesx8sgkyftesp8fxf9e7g5x6ytso5y X-HE-Tag-Orig: 1773691361-361041 X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1773691363-422143 X-HE-Meta: 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 HA1AdSi2 LouZN09kEyV8th7kt1ljNRyk0A/RxKaav/0rT Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu 12-02-26 11:21:11, zhaoyang.huang wrote: > From: Zhaoyang Huang > > Nowadays, ANDROID system replaces madivse with memory.reclaim to implement > user space memory management which desires to reclaim a certain amount of > memcg's memory. However, oversized reclaiming and high latency are observed > as there is no limitation over nr_reclaimed inside try_to_shrink_lruvec > when MGLRU enabled. Besides, this could also affect all none root_reclaim > such as reclaim_high etc. > Since the commit 'b82b530740b9' ("mm: vmscan: restore incremental cgroup > iteration") introduces sc->memcg_full_walk to limit the walk range of > mem_cgroup_iter and keep the fairness among the descendants of one memcg. > This commit would like to make single memcg's scanning more precised by > removing the criteria of 'if (!root_reclaim)' inside > should_abort_scan(). This changelog, similar to its previous version is lacking details on what exactly is going on. How much over-reclaim are we talking about here? Is this MGLRU specific? Why doesn't our standard over-reclaim protection work? > Suggested-by: T.J.Mercier > Signed-off-by: Zhaoyang Huang > --- > mm/vmscan.c | 4 ---- > 1 file changed, 4 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 670fe9fae5ba..9d900be478ea 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -4832,10 +4832,6 @@ static bool should_abort_scan(struct lruvec *lruvec, struct scan_control *sc) > int i; > enum zone_watermarks mark; > > - /* don't abort memcg reclaim to ensure fairness */ > - if (!root_reclaim(sc)) > - return false; > - > if (sc->nr_reclaimed >= max(sc->nr_to_reclaim, compact_gap(sc->order))) > return true; > > -- > 2.25.1 > -- Michal Hocko SUSE Labs