From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id DB008606A33B for ; Tue, 3 Nov 2026 11:37:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=ionos.com header.i=@ionos.com header.a=rsa-sha256 header.s=google header.b=gHW4SUQN Received: by kanga.kvack.org (Postfix) id DE13C6B05BD; Tue, 3 Nov 2026 06:37:33 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D92856B05BE; Tue, 3 Nov 2026 06:37:33 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BE5946B05BF; Tue, 3 Nov 2026 06:37:33 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 8DA046B05BD for ; Tue, 3 Nov 2026 06:37:33 -0500 (EST) Received: from smtpin04.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 1C0E2403CD for ; Tue, 3 Nov 2026 11:37:33 +0000 (UTC) X-FDA: 85393607586.04.B2666D2 Received: from mail-wr1-f42.google.com (mail-wr1-f42.google.com [209.85.221.42]) by imf14.hostedemail.com (Postfix) with ESMTP id 38E7C10000C for ; Tue, 3 Nov 2026 11:37:31 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=ionos.com header.s=google header.b=gHW4SUQN; spf=pass (imf14.hostedemail.com: domain of max.kellermann@ionos.com designates 209.85.221.42 as permitted sender) smtp.mailfrom=max.kellermann@ionos.com; dmarc=pass (policy=reject) header.from=ionos.com ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793705851; b=uST1YlMzAv9mPJyd/nmOj5vYWdEzLQs7aWc1To5JZTRmJJOVzU2lhiy2cMhH4KYH0eokE5 Ax+/uiEtNX48SkipHRvsHkLjz56q+huAoamSoinQKyjt3Y/EwzYuMirSMnyVo+ECW/jKUI jneCAbwOAtojThWy/Wva1DFDHYiYTpc= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=ionos.com header.s=google header.b=gHW4SUQN; spf=pass (imf14.hostedemail.com: domain of max.kellermann@ionos.com designates 209.85.221.42 as permitted sender) smtp.mailfrom=max.kellermann@ionos.com; dmarc=pass (policy=reject) header.from=ionos.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793705851; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=IsKP26C+4uK+emKCr1xcjNZltVUV41qm/vZF8BC5G1Y=; b=uaHOR7RI0Q1xKYfrng57G6DPtS0oi+rC3rF99meq0KVykAJ+Y/9sRxmsVJPsBRZTJPizGn onNahCpQSkHbzqI1tmmHoVora9ss39dsMOVYY8DLTjproWG8Dj5Zuic5l7eNnNhVBrbpa8 yYwGTkbLliYIl1zI10TIB2banlSY7ss= Received: by mail-wr1-f42.google.com with SMTP id ffacd0b85a97d-48afbd2c386so2350931f8f.3 for ; Tue, 03 Nov 2026 03:37:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ionos.com; s=google; t=1793705850; x=1794310650; darn=kvack.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=IsKP26C+4uK+emKCr1xcjNZltVUV41qm/vZF8BC5G1Y=; b=gHW4SUQNxYQHCKGVFiEz8H0TpFtmDWpow4PW94iEAeQMjbcN1Q3K6N/vgMGjz7KlSY 0WYMAr7FhMAIqnsNoTQew1YMBUpJle+IzOm6SkKyNX2nFq5JMWyM1AJtMJYClTFKQJwo N+EtxzmqYWewyF1l7TwRHO4jbd6T0X5xiIWJUpW2xp7vUQcj+dCR3lKwqJtO5ECPg9ob 24squE7mpweRGJbHME9xAW6XXHI06ft0iy5iI4DXIqVkfhYvcxWSeVEax+f1utX7zy/P mYP/lbgBu1Ph5wg4Uz3gnPkVoeEuj27ffI0qDdYuRKfFjOJLng+FgkxU10ejwWmFZlWM 225A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793705850; x=1794310650; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=IsKP26C+4uK+emKCr1xcjNZltVUV41qm/vZF8BC5G1Y=; b=NSz45mMU4kKS2j0H/4VfF9hlNfybIo5O879NEEWca2doOZkq1nJamTlwNL+UaAZVf/ yJMlS+53De2GTjzUdoGcRsZbxSN2szM7cGwRphauZOmuPqUd6KEvC2iQ5yfiE5SVwarl 6LXERCqQ0B2KApvMFL2FlWzR00sCIJ0EeD3HkstUmongkJc3sqvm8hcR2GGlfchOvUJN 51/VLYUDlu5FDQcAd+YPA7nZqwWDZZ0qiezPYpjQhR1gyGshh9kEE32shP0YKQdiYZtX fsfkJLd0mvTsLCeipgl6j0Hx1+8r3Nvw7zop/fXsGkSR2Z46o3dmO2jZ+7yrmkako4jA vYeA== X-Forwarded-Encrypted: i=1; AKwUvByMvNl+Dgj9WyycPb0l/2OidoU6haR0V2YzbiCWSmOpl5Yz/m86E6bZe19ywMn3OuZ0o1cOrYE6Kg==@kvack.org X-Gm-Message-State: APuU4Z8lA3OQdMFiFdK4nBgazFAoAvWaJJ0M5aq9baFrLlIgernRXNTg PuyuT8ZulSw6ExJGRP4RPHVCwg5gXD800A7FgBP+KbGZumR0A6DVldLyMKdbrNSxLXk= X-Gm-Gg: AYBFou355LgERaDQ8dIA6WTve+7e1PWQmxRsjxwcjp7MQD8HCO7V2X5KR6/gclBTe0V sfypDQzNve4d+DUpPTxqVqve+Qdc+99GrQ7o10Ae1aOcpJBHy54OhBzNVbiD397O7UW2YUVZMEC TGIJO7/eN3K1vq+x4OPZOxCtIDWh/V57utrHLnqCvtQyyFYAzEAd0PeqazdPmDkJKIm3F2gRQlF LYH7lEjp3CxuMjYTZ0U4IDKiNu9bFCrBIuIhSoMWQ3vyoCeZd5a66XoNM9qP2zgOCaNoYfjr6ag lyogx432pX21dSM+bFdH3hpKZ1dVZzJQpnNxggrCpsFdLMnWIYFGj3H1gbyx/IWuO8GkHv8mdpf ogCfFk2l46uPwfQ73Vu+oFS6GrnBymizMAKO3TwJ0ttkH06dGfwWyWBL7c4qrLfqwj2dxfgGH/Z vJmVXvy0YFIDrXcxQ5ZIu4z7V/CgAPnayn3d4atb/wXM9hd/5hiPGRLqqD+LOWdouA4K3V0doYg 61C9Dr0Jw+4MiePWJKT3m2MGY+uD4wEjr2mmAPS35ir//B+NDBzfRs+g61LHSatc7wBn6ldXakA de3A3/8KaZNlLRL328VYseTHk+bezSxj8J3akEZ7HAr2voyxJ1c8604r3qMfAeCwraxotgcBidt vT1ubIAG3NCy+mAaLF9CEtv0JiLCpsw== X-Received: by 2002:a05:6000:240e:b0:48e:76ab:78f7 with SMTP id ffacd0b85a97d-48e76ab7f2bmr21607663f8f.20.1793705849795; Tue, 03 Nov 2026 03:37:29 -0800 (PST) Received: from raven.intern.cm-ag (p200300dc6f04b700023064fffe740809.dip0.t-ipconnect.de. [2003:dc:6f04:b700:230:64ff:fe74:809]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e71b78f95sm23000997f8f.28.2026.11.03.03.37.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Nov 2026 03:37:28 -0800 (PST) From: Max Kellermann To: akpm@linux-foundation.org, kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, baoquan.he@linux.dev, baolin.wang@linux.alibaba.com, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, hannes@cmpxchg.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org Cc: Max Kellermann Subject: [PATCH v2 5/5] mm/mglru: reschedule between memcg reclaim attempts Date: Tue, 3 Nov 2026 12:37:10 +0100 Message-ID: <20261103113711.1832834-6-max.kellermann@ionos.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261103113711.1832834-1-max.kellermann@ionos.com> References: <20261103113711.1832834-1-max.kellermann@ionos.com> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 38E7C10000C X-Stat-Signature: pg8dfgafc3fp34w9s9tx9o9iqgqyqtpb X-Rspam-User: X-HE-Tag: 1793705851-51665 X-HE-Meta: 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 IhDE5SRz A/EUwmiD1ixb5uECSjta5FqdjN0ktPJ2aPePxOKsDJ0ONYJ8hFgsTuL4EY/EPDEYKoJL0BEobW5gqgMhi6+3lkwAKkMU8J63IzXnRZsEiB4REnst8QvNlKlhL5BjeXCXBwrQFyDVefAQrAiqKnqdrZlbX5gcpl5Mw3MQUAlLWgKRlVe5hkF7Tv27ScfF4F40ZwyzWE1UVBjkr1ZmCiGjof5tWFjK0uceenlZiFdSGgQxCf6tVkaGEDbLdrQIpamxTpJJBJk88evIGe0u/oJnCNMLUrjJOdX1ZjdZX1cI1/s2gv85iC4NavgI/1dlBVqUPuy9+Ayx5uCd6+0TF106VT1yklg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 shrink_one() can return immediately for empty or protected memcgs, and try_to_shrink_lruvec() can break out before reaching its cond_resched(). A scan through many memcgs can repeatedly rotate entries without giving other runnable tasks a scheduling opportunity. Call cond_resched_tasks_rcu_qs() (as the existing shrink_lruvec() loop does) after shrink_one(), while the memcg reference still pins the cursor and before reacquiring the RCU read lock. Also call it between bins and nulls-marker retries, covering scans that skip every entry. Signed-off-by: Max Kellermann --- mm/vmscan.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/mm/vmscan.c b/mm/vmscan.c index 899f756bd15b..5dc5e698e243 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -5395,6 +5395,9 @@ static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc) gen = get_memcg_gen(READ_ONCE(pgdat->memcg_lru.seq)); bin = first_bin = get_random_u32_below(MEMCG_NR_BINS); restart: + /* Yield between bins/retries that contain only skipped entries. */ + cond_resched_tasks_rcu_qs(); + op = 0; memcg = NULL; @@ -5425,6 +5428,14 @@ static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc) op = shrink_one(lruvec, sc); + /* + * Empty or protected memcgs can bypass the + * rescheduling points in page reclaim. The memcg + * reference pins our cursor while we yield outside + * the RCU read-side critical section. + */ + cond_resched_tasks_rcu_qs(); + rcu_read_lock(); if (should_abort_scan(lruvec, sc)) -- 2.53.0