From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4BA8FC47DB3 for ; Fri, 2 Feb 2024 13:00:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D9ECB6B0072; Fri, 2 Feb 2024 08:00:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D4F9B6B0074; Fri, 2 Feb 2024 08:00:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C174C6B0080; Fri, 2 Feb 2024 08:00:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id AFF156B0072 for ; Fri, 2 Feb 2024 08:00:56 -0500 (EST) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 8033F140FD4 for ; Fri, 2 Feb 2024 13:00:56 +0000 (UTC) X-FDA: 81746873712.20.7C3787A Received: from mail-pl1-f180.google.com (mail-pl1-f180.google.com [209.85.214.180]) by imf09.hostedemail.com (Postfix) with ESMTP id 5609B14003C for ; Fri, 2 Feb 2024 13:00:54 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=bytedance.com header.s=google header.b=BJLfZzcO; spf=pass (imf09.hostedemail.com: domain of zhouchengming@bytedance.com designates 209.85.214.180 as permitted sender) smtp.mailfrom=zhouchengming@bytedance.com; dmarc=pass (policy=quarantine) header.from=bytedance.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1706878854; a=rsa-sha256; cv=none; b=BRFtEKd2aM1vfxBdv78LOAVx+fJ6yAC78bE8rINFfnxoXC8UPdc8NrKrL86Sew+ec/YyqI XU1MhrvljB0sS9f7FDaMbeZp31lbblBzTkeGC7xZm52l5o3w6/uT0msIn0YBCctPUvdUcx D6h6MuTyGWiDvbeOe3CgpydtCekiq4c= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=bytedance.com header.s=google header.b=BJLfZzcO; spf=pass (imf09.hostedemail.com: domain of zhouchengming@bytedance.com designates 209.85.214.180 as permitted sender) smtp.mailfrom=zhouchengming@bytedance.com; dmarc=pass (policy=quarantine) header.from=bytedance.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1706878854; 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-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=G2bY4vYtweXh8leJIICu6NBbyGqLWwvL3EkmAcH4Epw=; b=rNSblaKp2XLpqWNFftG0hEChF0oLiF+BXAvJzGKYJHf1N8ylWxfZvWcjbtboYA3pM6fmGY rI+eBwt4Qi7g7L9neQkZ5yHDEyysp7imxTptprKx/LK7kxf82KeAL52T0HeLqUxIb64HYi uxHo9bbNMyxEucunxT4kJ5HxGeCwFVs= Received: by mail-pl1-f180.google.com with SMTP id d9443c01a7336-1d780a392fdso17252495ad.3 for ; Fri, 02 Feb 2024 05:00:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1706878853; x=1707483653; darn=kvack.org; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=G2bY4vYtweXh8leJIICu6NBbyGqLWwvL3EkmAcH4Epw=; b=BJLfZzcOS4LC9vdZJ3XgLzvjDyop3sAN2F5DVeSvy7X8dO2P0CBVHk7uuBOngYNGMp MLHGSnbyOLBBVVrrXQ/SdNPc3aR0fW4n1feyF01xeQqvv6DJyiUNt26pwSAmHvFMqbuI gJ7CBrVfDLDCVL0kkZRE1EqQZENV1lXKXhk0pXbrmTAmnyhtxRlPPI3EdyQiN4nkVSZD hY8RNNqx+BdedHY+hrLDLPt1ey9d5B4p+nWld84jrBOp8NJ/D7xQ4686cq2Il9qWgjYx Yb9tvwhqt4MQMo3msaAXuuvHu2m8GleqxO54E5XcjMwLk8XUb2nk+Um5lS7zens7rtl/ MXrw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706878853; x=1707483653; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=G2bY4vYtweXh8leJIICu6NBbyGqLWwvL3EkmAcH4Epw=; b=XwOpKfgQYthDRJgElXnedTqr2o3wqWyvWupPhcWdR9Pd5w86BZDku2k7pZuaFDkSau Ng+3Go4IMvk5uBOZPPx+ie/MCYnw/dVUGnS44Bp2MvuK7m8+Ska+TNKZCRF6LFa05ZvL cJ0ofIQrBAv+9OLXTTIs+JScQ3W1KCfnVYOWNfmBU4uUismHFFcZDFHKKYWkc9zgMDnc 7nMgzNWLQ1rKiGy5T3tn+rii2iyjRgh+6EvtdPjrzbmbMHXP0hWAEhiJ6few40RoY3dk pp6Yzb9oOYMrHSAmASdz4c95yhKd/5ZScIIhlIGT2wxU46eq8ROq57xuvFZDezhgZjKs IeNA== X-Gm-Message-State: AOJu0YyH7t6AzswEH/dJY2R7cl2fGF22W6sh9BFJQ2quXwRv6IP+St51 jc1cMgCKTYfwaGLrH193YhqTRbDXPNB526MJGJhjw8vKzMCtEefHIHzDSjVH0978c5Da19f6Wx4 D X-Google-Smtp-Source: AGHT+IH6qu/ikgZszTBTu6hyUMxDM3HZaGJQQLqAdta57+0lOVP89oelOwELMxcPFjTdnXBV7I5dzw== X-Received: by 2002:a17:902:e54e:b0:1d9:55b:6a2f with SMTP id n14-20020a170902e54e00b001d9055b6a2fmr6469415plf.48.1706878852785; Fri, 02 Feb 2024 05:00:52 -0800 (PST) X-Forwarded-Encrypted: i=0; AJvYcCWj0I7Q3oG9lnP3Jthb1RGY+JzyyyC3B8DgwwQ1UmoAcVKTX29lKV5lAd2N1KGMWw+aHnhd/kOi4chN/v+bqpqjm1Y4UsXkCfix7LbaczNk5LsTSP4zhw4qbVY4l2jbsRuaw6OQrz0g+iXusaxYrLwMlU8rWlAbVZpzf3pMcJhXfsWeuwyClrLJf2csgSEOSQ== Received: from [10.255.208.99] ([139.177.225.251]) by smtp.gmail.com with ESMTPSA id mn16-20020a1709030a5000b001d9033b9d8csm1567243plb.59.2024.02.02.05.00.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 02 Feb 2024 05:00:52 -0800 (PST) Message-ID: Date: Fri, 2 Feb 2024 21:00:48 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 6/6] mm/zswap: zswap entry doesn't need refcount anymore Content-Language: en-US To: Yosry Ahmed Cc: Nhat Pham , Johannes Weiner , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20240201-b4-zswap-invalidate-entry-v1-0-56ed496b6e55@bytedance.com> <20240201-b4-zswap-invalidate-entry-v1-6-56ed496b6e55@bytedance.com> From: Chengming Zhou In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 5609B14003C X-Stat-Signature: si1fuxbw3noz9d93y7r9iozrd58zqzcd X-Rspam-User: X-HE-Tag: 1706878854-193411 X-HE-Meta: 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 7kcvv9QB wDt/pplLmpTrvB4bjQxXvAvumx03a5WOzhIjf4pkxKYWqFxWivu/OXPBLsmdh1kz9H2KYoLKZ2Y4AjTGjhgd9wVzUUV3in6pLq898BdoIECx9dv1mAm5TZWuIKs2XYqU6+coGX6FhGduf6gTSUj5AwZPYzj1X6YWXFcuSSvD+QOIriHDzFVAgLTUuij+BvpjD3KqXF5SDn8YHvR2YHvqdgVid7ykkQmexXLm5X8Llj67S0L0nMKoJoVqb2/0GezeRQi/OstYDtg2g6Tah70wFfJPzpkwKKq/W3p2doRlcSEbC+x8/hWNYTqyHx+50hs384SPVXBKPdgThELUZCOQNaSuKoHvj9Tj1whxBjBeFD5Z/GuOMNfyLo+zzsXxG55bz0DLrZOMB8f7bWK2z+3XI5ZIicO4+ECMLe1IPiq7FN3F175C2omvLavLQzwJfaOObjaWrr/enHaAV3tE= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2024/2/2 09:11, Yosry Ahmed wrote: > On Thu, Feb 01, 2024 at 03:49:06PM +0000, Chengming Zhou wrote: >> Since we don't need to leave zswap entry on the zswap tree anymore, >> we should remove it from tree once we find it from the tree. >> >> Then after using it, we can directly free it, no concurrent path >> can find it from tree. Only the shrinker can see it from lru list, >> which will also double check under tree lock, so no race problem. >> >> So we don't need refcount in zswap entry anymore and don't need to >> take the spinlock for the second time to invalidate it. >> >> The side effect is that zswap_entry_free() maybe not happen in tree >> spinlock, but it's ok since nothing need to be protected by the lock. >> >> Signed-off-by: Chengming Zhou > > This looks like a great simplification, and a good motivation to only > support exclusive loads. Everything is more straightforward because > every tree lookup implies a removal and exclusive ownership. Right, much simpler! > > Let's see if removing support for non-exclusive loads is agreeable first > though :) Ok, I have just posted some testing data for discussion. Thanks.