From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qv1-f46.google.com (mail-qv1-f46.google.com [209.85.219.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0E0B31D90DD for ; Wed, 17 Dec 2025 22:18:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766009925; cv=none; b=c8425RPhbBuv/oElxovFjXFnyxP3fqwjI06YGZwZlP0Jdr/bG6x4ja4nllg5WmsauLsaT5yqvbgC/ddmoWgDYdQsfILc34sTbBKrOWgU9cY3B/cBkD0iJ3qkzjOk8C7ZJCYZROFOL7KDfHkLkSkNBRtcbVtz3PqileVco8RzSK0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766009925; c=relaxed/simple; bh=NiEiLJCQ3mqiOkwKSwuCbSI5AlhBCxb3t1MXVPq1puQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=PIYRxKF2grXns7jEImQGHF0PbrMjxje3ZHpQmeJn+Q0glLFsc9HkZobbZCKJBnVieM1UmAGm3v7saRd2/pVZ4H7RoGQV2ZDp3E8f8ZxXyXM/iXjnYlbQE6J8j+RzcPbIUk+ltZIUH4PvVi+L4nefgBU4pvbDwpQdYrl2mTs3iBU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=cmpxchg.org; spf=pass smtp.mailfrom=cmpxchg.org; dkim=pass (2048-bit key) header.d=cmpxchg.org header.i=@cmpxchg.org header.b=rzWH+vIA; arc=none smtp.client-ip=209.85.219.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=cmpxchg.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=cmpxchg.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=cmpxchg.org header.i=@cmpxchg.org header.b="rzWH+vIA" Received: by mail-qv1-f46.google.com with SMTP id 6a1803df08f44-88a22eb38edso7306d6.2 for ; Wed, 17 Dec 2025 14:18:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg.org; s=google; t=1766009922; x=1766614722; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=bXcbwNkeZlIMBZPQNBardsHsUWb/8fu2HEpQ4xgxp4E=; b=rzWH+vIAOF3mCPep39JtSCg3EhNkOO1MzTgmY4/9sxh3wQh8R8xLEfWatxN6hJ61Eb 50HNdrOKDhoMXd0mgfuo8eFj7oxeTeNx1OVoK4D99bkGMUeLChjSql58uEnYR6yEyYUS fWtGM+7qXs7MpTJUdV+o9/ST5ncgxabasa4C56DoA1FAaFk5id2+Jw+CoMqxMF9PBsXz hYH3R7DJcQ4/V+/2sArIusbJqPrcEb7omxjQxYqv+TPI9C1NSQR6Ns1NMEt2DA7VD8CG WKMpt2Eae4KXwrF2t7ilFVQL+g69HAwKas6M0hJ7fFAkhwVz4X1Mvz9t+fVgXlYUMNq9 WmRw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1766009922; x=1766614722; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=bXcbwNkeZlIMBZPQNBardsHsUWb/8fu2HEpQ4xgxp4E=; b=bOajnEePaovfQmQ3Arel8FRA4caUS3/c/oIDZ68tE1vQmHDv3BJt0KjwWuHGvClL2y xHy49LgfJtjQAzUgSbfSqgs+qJGnYq3FGmXIbDRPZnjmyUw4KpgELgtPJHa/KWcdm7nG 1ObmkWCPFzpkD4luX480ieMUxKxz4XT4h9/TB4ddpOtsn4XBAGERjxziahiu43PjGcFx A2M+tiR9TZwXPLTaujdNLaevZp20u7M4sRVNboXJm2BZJb2cxeuf6ME68EVTUS8QVRUr m89HsPeJ9I3TQ9YuBhvDuWdOYDWdCeoA36rhlQ42mST4/L36gyKL2fkMoR8Fzr1rCcNM DBkA== X-Forwarded-Encrypted: i=1; AJvYcCW4Pr64noJFghjOYazEjjMiNa2En9Y8J3O1T0qTAkn2SXwHEqt93Edgh1aEgLo8REz3whAF7lCLaXIpt/E=@vger.kernel.org X-Gm-Message-State: AOJu0Yx9fk32KEpveXGBKTWX6VISttK7yrjByIUiIFc2dKRfm+Ywwujh AGbq6lXQxJrHbTOhcccGHoyaBj/itvmb7rYp3x7mG/L95b0x0fVg/EQUYbl0O7WAXB8= X-Gm-Gg: AY/fxX6KGrvtACXnyIJTaOzgKpmjavnvWK/Gik1TC6FIJPvJy7QTOXMA0RvdVTFpt1/ 8FjTmFJQeLch3ZktilYWi+5PRSNDk8dcm/LBsVa+ZGgk70m5GPgiOnPkwS/Hzuv+Rs8uF1yLosp 3h3mk2TRCm4hXzVdt2/ud+30iTdnVbDGC8t88FgQFqmqnAAZjR7fNO7ubw89CAMLgidVr1j9c17 WvlZa0JUgudGDwfkzbyM+nq6ejtyLOU3un1pLCneGyJb4hG4fVTiTq63TMBcilMnvHuTLFzx/H5 gyVrqk+hD15V9+5u/IQJLCmYS5YQzuErFSoKeC/65Em9hcQbb13ucDNILfy30x/AbHlXjmqHPbr y/0WT+dN/7iVgB39rnF4umrSz85PwDBNaBgimuXuHGVaBncFL5dTsZE/tpGFwV43hPxyLwrlYBy GI5KN1rjtztg== X-Google-Smtp-Source: AGHT+IG1f7aReTFQRW4F2M0CyUDBY2Hjp5SXYzk7s/J18pLYnuhEkDgo3DdJ4s8MQTcbTc1pUU5ITw== X-Received: by 2002:a0c:edc3:0:b0:884:6f86:e096 with SMTP id 6a1803df08f44-8887e7a0854mr204953976d6.34.1766009921932; Wed, 17 Dec 2025 14:18:41 -0800 (PST) Received: from localhost ([2603:7000:c01:2716:929a:4aff:fe16:c778]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-88c6089aecesm4698286d6.32.2025.12.17.14.18.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Dec 2025 14:18:41 -0800 (PST) Date: Wed, 17 Dec 2025 17:18:40 -0500 From: Johannes Weiner To: Qi Zheng Cc: hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, harry.yoo@oracle.com, imran.f.khan@oracle.com, kamalesh.babulal@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, chenridong@huaweicloud.com, mkoutny@suse.com, akpm@linux-foundation.org, hamzamahfooz@linux.microsoft.com, apais@linux.microsoft.com, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: Re: [PATCH v2 14/28] mm: mglru: prevent memory cgroup release in mglru Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Dec 17, 2025 at 03:27:38PM +0800, Qi Zheng wrote: > @@ -4242,6 +4244,13 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw) > } > } > > + rcu_read_lock(); > + memcg = folio_memcg(folio); > + lruvec = mem_cgroup_lruvec(memcg, pgdat); > + max_seq = READ_ONCE((lruvec)->lrugen.max_seq); > + gen = lru_gen_from_seq(max_seq); > + mm_state = get_mm_state(lruvec); > + > arch_enter_lazy_mmu_mode(); > > pte -= (addr - start) / PAGE_SIZE; > @@ -4282,6 +4291,8 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw) > if (mm_state && suitable_to_scan(i, young)) > update_bloom_filter(mm_state, max_seq, pvmw->pmd); > > + rcu_read_unlock(); > + > return true; This seems a bit long to be holding the rcu lock. Maybe do a get and a put instead?