From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj2-f13.google.com (mail-pj2-f13.google.com [74.125.227.141]) (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 C9FF84E5358 for ; Mon, 28 Sep 2026 15:19:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.227.141 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790608797; cv=none; b=BJEbdd+HvLIzlVnRESt2tYW45Y1DnQp8C8KCYgwgxTl6knQbTbH4tLfTJd0rH74T3hXLVCwPYwagrcdy84rIAdpUWxCBN+rNKRCgyA+7IwkE5NELpZx56FyYGnYPw1E9//G99yoH3NGUkAB0GTzHEF58DoZrsaogBxkhh7GwsnY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790608797; c=relaxed/simple; bh=4hBQ6kfdK8l+m9caQJD8zZXgKlYL1BsfesWiWNE6vU0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=T6y0sfU/hWyvE2snoR2Ji1kHDc2DoLavq6vs0upO99fW8SPmrxaCdRu4zPvM8T1GPrIxJA4b82PduK89ih/yw77BNPDJRJDuRVtGdbCzppvjCosi3cy0ecVnooojBIW000swp+oPaM7O1AqHG60TcL9Z7Edb1bUQTbIBQQXcCqE= 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=sAjDAk3W; arc=none smtp.client-ip=74.125.227.141 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="sAjDAk3W" Received: by mail-pj2-f13.google.com with SMTP id d9443c01a7336-2d747ec6188so14819725ad.3 for ; Mon, 28 Sep 2026 08:19:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1790608795; x=1791213595; darn=vger.kernel.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=EQrjkRZQeuYzERNWt13KrmtO7dHmdt8dryvfZkIliO0=; b=sAjDAk3WoCaqK5yz24zQoH9g4qbtUJ56hp0GgVu73h4G1aMu5+QTzcCvureyhPcMuy 3a2VJp4h5XrS/Ul5WgK0emp8qWKINH4xR0isVRgVmacktZwHuv7z79OTrCHL3LRbd7vY tgYAUj1VQzyU7ZzZy/idF6f9JK2i9TGtaaf3ljNc2atf5YzveV1f5GCOFnE27s4pXwWL sjA+DKTZV8BovZtAiP2pPYFumeU0ayQI6uoH5GQykWH5/f884Do+RL2AYw5Gh6+JJcT4 2+AqFit4j/ingUD4uABr45QUkaS1pqVIPiRLKQ8FcIWHCN2X+/kBctE9nsRExTxb1DYw G5Dw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790608795; x=1791213595; 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=EQrjkRZQeuYzERNWt13KrmtO7dHmdt8dryvfZkIliO0=; b=KKhulCqjXdGABdKDheZk3kxYV8g1cTgiDxr+n73DXtKhd45ZDPmODXFZUffaC8XS7m QXbua9HL9GDAXBrdmmm6QruscbtlMxfoEXkXVUAoAi78HKpJiogtKGCkVzStLXnJF4V7 AjM7Nh/kTPGHhuuRC7M7G1V/OThe+UCyK+xBzFxZiBbYujkZUsIiZ9t9c+N16lnL8Pgr VofGPxrHoygkik0T5ikRvrGS1MJU3ocP3VNr0vBdj7HcLIWu05ShamaYFTeVG7p1cRq4 aswjqiaNSqGxMj0RCPRT11ogQSauZOOdS/yD2XkOIlIR3WW9Y2hfEQqBoApjbnY2Jv2k A2WQ== X-Forwarded-Encrypted: i=1; AKwUvBwTinY0aPDON3t4UE8drj/hxUMmJIn99clySzFA9CAfDs3aHdDU+SylDYyBt5zQE2eDCxLYo0zN@vger.kernel.org X-Gm-Message-State: AFq9FYLxb1vgRsdHi9FmwuDOjFpNil7y7vDtzTmXcWIb7fbjgvVbZ2TP 4PQtVB7aMG+0Dz2zlmXTioSLomM020P0Et7EPF8HJ8aIGrpr35hWei8D X-Gm-Gg: AYBFou0yS0FmMyL0YCTWJdOWvKUdKRXsoYNOVx7kFsqVPSLLYTt0r0X1+AY6xBoHP+5 cX9qk0hYIELbxXviabefMy4GnG85MhOp4a5bo5WJGtobN0Bs3V5Y3jntLK2Lt/VKtDBr6nxW4ac 2RVLQ3POxrEfj4iT/v7XScqqyhw3L9LfsChIC6p+zz9LPyYpfRemC+HkEZLtbxLBghJp4gRLrR8 MgF3tWeAEJNXL0aZ6iHZdQNl3Q4LGQa40d1Mwp1BjSMURf4fG2BwViNR1JcGUQGqPRa9To9QuYA wpfBuSntLE8YtJ/ora6AokJJEkpLuRR1eFSPed6LoYP4awCL8lfqeLCS+MjVwhdwBQwhAwmrkP3 JUwTk1RzaGNqZPOR/FBhlB9KyVsnwi/HAAJhqYLG4ed13QdILJLsnXrngYH5rJbm7NNxUTuuJez QzFY7FiDPmAGksNRY52NQOeLP/tmMmYaoTyIed1wS5B8avR+2OTXS7mS0amZ90twHLgCdIkd7wp iCPA+rK4Hxx5uA1zAIeDyCTqSHl31rx8bpbnt006/nX/WMEkC4w1r6z/6nq3PnMinOfQcqZXrYz awh65lNgurQWZMbU/nCmW7AU3jVgHfmJfHxLuLGbi6LEten+ZrWTm3qj9ps= X-Received: by 2002:a17:903:1987:b0:2dd:3ddf:b87a with SMTP id d9443c01a7336-2df7da68a41mr101388085ad.0.1790608794891; Mon, 28 Sep 2026 08:19:54 -0700 (PDT) Received: from spider.bream-herring.ts.net ([103.6.151.236]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2df91423df7sm43558615ad.43.2026.09.28.08.19.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Sep 2026 08:19:54 -0700 (PDT) From: Matthias Goergens To: Kairui Song Cc: Andrew Morton , Chris Li , Youngjun Park , Baoquan He , Johannes Weiner , David Hildenbrand , Michal Hocko , Shakeel Butt , Kemeng Shi , Nhat Pham , Yosry Ahmed , Barry Song , linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-api@vger.kernel.org, Alejandro Colomar , linux-man@vger.kernel.org, Karel Zak , util-linux@vger.kernel.org, Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Simona Vetter , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, "Rafael J . Wysocki" , Pavel Machek , Catalin Marinas , Will Deacon , linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Shuah Khan , linux-kselftest@vger.kernel.org, Kairui Song Subject: Re: [RFC PATCH v2 0/4] mm/swap: reserve swap areas for deliberate offload Date: Mon, 28 Sep 2026 23:19:44 +0800 Message-ID: <20260928151944.2686626-1-matthias.goergens@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: References: <20260926045517.3458413-1-matthias.goergens@gmail.com> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Kairui, > Just like we already have a "swappiness=" parameter in the reclaim > interface, perhaps adding a "swap.tier=" would be better and much > cleaner to achieve the same goal? Based on Youngjun's work here: > https://lore.kernel.org/all/20260916183437.2946306-1-youngjun.park@lge.com/ Thanks, I think that's the right base. I tried it: on top of Youngjun's v11, a "swap.tier=" argument to memory.reclaim is about 40 lines. In a VM with zram at a higher priority than a disk swap device, and a cgroup whose tier mask allowed only the disk, ordinary reclaim in that cgroup stayed on the disk, while memory.reclaim with "swap.tier=" pointing at zram went to zram only. What it doesn't cover yet is reclaim outside any configured cgroup: under global pressure, a cgroup nobody configured still reached the zram tier. So for v3 I'd like to add a system-wide limit on which tiers pressure reclaim may use, on top of the per-cgroup settings. I'll wait for Youngjun's v12 and build on that. Thanks, Matthias