From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f182.google.com (mail-pf1-f182.google.com [209.85.210.182]) (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 2FA6341F5EA for ; Fri, 24 Jul 2026 10:22:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784888535; cv=none; b=XduOb/0rS/+Tfuo9xztzCbX6aMzrZLbjX1qGoIdBZkwLH+SWBHzzaL9kHpeNp1O+ds1dVjhRxYEeB5pR1dtFxD8xYZueEaNN1xM2g64fThL0TG4WuHsvhaj0Tf3i+9NTWt0/IITeu8Sa6YC5rch8/g7LDY7iUGf6iL0o24pnrfk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784888535; c=relaxed/simple; bh=EHvWl82n0n7uzF29LI/GYIha5plZ2gekMSFm++1M26s=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=tMOCvmjhD15da94pRLHENtNImXygueoMp3gTZkJODUwwinpxAJFnd3S7k1nNILtEmjFimNBLSqKAyyXGYfOliaVm7eCtz1ZsFqiXczFSowmYilJkja+cgsSQEXYcRb1yQJC4mUBXsgT0J7gPbD1T/vB3UlOb/s9+sMmD9w1T94o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=tGki3KfT; arc=none smtp.client-ip=209.85.210.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="tGki3KfT" Received: by mail-pf1-f182.google.com with SMTP id d2e1a72fcca58-8484f229529so148438b3a.2 for ; Fri, 24 Jul 2026 03:22:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1784888531; x=1785493331; darn=vger.kernel.org; h=content-transfer-encoding:content-type:in-reply-to:from:references :cc:to:subject:user-agent:mime-version:date:message-id:from:to:cc :subject:date:message-id:reply-to:content-type; bh=PjEtanJscU+kRHtICYaoHdn0dLIQ0TxUX75oiJzMbAk=; b=tGki3KfTtaygut4cbC7NxLDgI0XW+yq8UVHtMe5vreWmKMAg4F08yfkN5kgw4Mng6o 82GDotNe+nZ5huGszSMvkmhsFu5ltUAMsfKAQ1UniUBwLYNkm9nZhU7LzgReNn/iQoHS GBIZef90HgS6hvWvbxlyS1micgmlX1K3Bc/X6//tJMDNlWCH/X9krw7HTAvLVgdt31aJ 00NubZBZbX1UY5+LdwUc/krcSGNUPWmqIZ0Oi1NOeXSNr6TosBCrtnXXNiUWy63rtj8k SvGYnUvWQHQwQuBqV5yHY3Vl4QA9tn5Sm2qgDlE6EJiJBzIiEmJtsXj3rKq3ufgOb72n Fv3g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1784888531; x=1785493331; h=content-transfer-encoding:content-type:in-reply-to:from:references :cc:to:subject:user-agent:mime-version:date:message-id:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=PjEtanJscU+kRHtICYaoHdn0dLIQ0TxUX75oiJzMbAk=; b=g0twDmBb5aJRU0Ga64kCYYvNf9tfSi4+3m9rUM0mOiWI7Pti9lvbfn6LlO6RJDMsL7 5pwsPVsyEe+XAkKEdpchpYaQa/m/HJRmHOxyzRMD0JEJs1NML6raGhjX4uE8imcMERn6 gJQndHypc6s03qJJCtB3vRWQ/B4MVYj6SrLjJ5wDikfEIIg98JKhDVsrkZxNPZPSVT3o DzbLdV0H9Nzxy/i4F6+13owhZNMK0BCyYwcTtDzl/Lwd0DLZ8AONOatTBvmTqLh5ji/S n34xoWde1DsOo8j4Ni5a9z2VjQQJpNVVrvM28hYgUTWplgK0TWLdt2QozrvdnglfXsLx wWgw== X-Forwarded-Encrypted: i=1; AHgh+RoWgY3U6uC9kwvu26LC/P+QglTibAs75VEKsYikysv0fKJQoWzENARVpSsH+aiT/XYGiy7Kc/Kg6d2w94s=@vger.kernel.org X-Gm-Message-State: AOJu0Yyb1jPR8ut7oM5tQY1ZoJp+xIuMgQNcFxw1iKSlThHa9ZA35CnP A2OfwFHsmPFPtU/LhH1CQ2X4SjrsdVEv1adAmbLQpKxQnBG46/U+Fd51 X-Gm-Gg: AR+sD10XxXbkQwjnnGHh6iWH+yAFoQsjl5jHMl5aD0hjGDiLX0tjewUYdtkU0UlvXce gdeM9rwPSWk9iy8C/+LwyP89Qo27G6Ib3K6XR7wdMUOd9U29eKgqvIheAnMTCGjSGK9oljZOsYC XCDwUYd+IFBwY2To401UoFS+hSiz830FZ0M54wgze6+SBPG7PAAjP0vhZ5FP34fDQ/cUp4Px1Cd R6FCBrUnVjy+gzugO5cv+eLVNN0/w3I0p7n63VyW0zMxDWwRTKDB8B9uMub7fbGfHtcfjdl8Zmp UWNtOaDznbXIL13A5wwTCO4HhDAKpY7ZfHO8odDM5taKGCQREpKXjtO2FkHOYX0gWL19xiNGqwL aLjwCoroZiHEjeRI9ZD4RquiSfZJWQLbmpeNL5leCxIz2lZHKz5Gzlyd2mmackXvstV3EkV00wK zmdojHESqB0nD778+CKJce3A== X-Received: by 2002:a05:6a00:ab83:b0:848:65fa:542 with SMTP id d2e1a72fcca58-84e2bbba2b5mr7126501b3a.53.1784888531583; Fri, 24 Jul 2026 03:22:11 -0700 (PDT) Received: from [10.125.192.96] ([210.184.73.204]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-84e17573c0esm4486650b3a.38.2026.07.24.03.22.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 24 Jul 2026 03:22:11 -0700 (PDT) Message-ID: <2e61a4e1-20ed-4fe0-158c-5a9d060ce01a@gmail.com> Date: Fri, 24 Jul 2026 18:22:00 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.15.0 Subject: Re: [PATCH v2 0/2] mm/zswap: Fixes and improves the zswap global shrinker To: Yosry Ahmed Cc: Andrew Morton , nphamcs@gmail.com, tj@kernel.org, hannes@cmpxchg.org, shakeel.butt@linux.dev, mhocko@kernel.org, mkoutny@suse.com, chengming.zhou@linux.dev, muchun.song@linux.dev, roman.gushchin@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Hao Jia References: <20260717085151.22822-1-jiahao.kernel@gmail.com> <20260717181839.c94d0335ccef0084707d3d85@linux-foundation.org> <20260717214031.8b22e9a37ea3b0c564b466f0@linux-foundation.org> <7dbde343-fbbf-6a1d-1785-ebf9f5a04f6b@gmail.com> <0a96b7ec-0d8d-2abd-afaa-739c562bc985@gmail.com> From: Hao Jia In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2026/7/23 12:49, Yosry Ahmed wrote: > On Wed, Jul 22, 2026 at 6:21 PM Hao Jia wrote: >> >> >> >> On 2026/7/20 09:26, Hao Jia wrote: >>> >>> >>> On 2026/7/18 12:40, Andrew Morton wrote: >>>> On Fri, 17 Jul 2026 18:28:04 -0700 Yosry Ahmed wrote: >>>> >>>>>> >>>>>> The [1/2] changelog lacks a description of how the flaw impacts users. >>>>>> Please describe this fully and maintain that info within the >>>>>> changelogging. This info helps -stable maintainers and others >>>>>> understand why we're proposing a backport and helps myself and others >>>>>> with timing decisions. >>>>> >>>>> The first line in the changelog should be sufficient imo: "Zswap >>>>> writeback on hitting the pool limit is broken when memory cgroup is >>>>> disabled" >>>> >>>> "broken"? Perhaps this means "fails to occur". >>>> >>>> But what is the userspace-visible impact? IOW, why are we proposing a >>>> backport? >>>> >>> >>> Perhaps the first paragraph of the commit1 message could be modified as >>> follows? I have added a description of the issues that occur without >>> this patch. >>> >> >> Hi Andrew, Yosry, and Nhat, >> Any thoughts on this change? > > I would front load the user impact in the first paragraph: > > Zswap writeback when the global pool limit is hit fails when memory > cgroups are disabled. The pool remains full until it is organically > drained by swapins or memory freeing, leading to zswap store failures > and pages bypassing getting written directly to the backing swap device, > causing LRU inversion (hotter pages with higher fault latency). > > ... Will done. Thanks, Hao