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 74734C46CD2 for ; Sat, 27 Jan 2024 14:34:27 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BCB9F6B0074; Sat, 27 Jan 2024 09:34:26 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B52916B0078; Sat, 27 Jan 2024 09:34:26 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A4A6F6B0072; Sat, 27 Jan 2024 09:34:26 -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 958B86B0072 for ; Sat, 27 Jan 2024 09:34:26 -0500 (EST) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 5B0B9C0942 for ; Sat, 27 Jan 2024 14:34:26 +0000 (UTC) X-FDA: 81725336532.25.F0C47C0 Received: from out-171.mta0.migadu.com (out-171.mta0.migadu.com [91.218.175.171]) by imf13.hostedemail.com (Postfix) with ESMTP id 6C79F2001A for ; Sat, 27 Jan 2024 14:34:23 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=xY+sW1vP; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf13.hostedemail.com: domain of chengming.zhou@linux.dev designates 91.218.175.171 as permitted sender) smtp.mailfrom=chengming.zhou@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1706366063; 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=ldE+n6NcSlOlUyv98rKcvvVoi59JjH0e26apZ4K5NdE=; b=wlTrjgP4DzDXYA0Yfkn6OrDn1oWuFlnizoyajk4uGkQYwOB13owtMe+URIqF278FZQKxEz 4orkGoZ+jhEEV8D14hDaOw+qcZSKUUPw6I7pV0YspO/h/YjjLZxXdWxVgcaXKwdUOjwnJ4 dlADcFTxSrhpqhFkOObZmvETWvLfVEU= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=xY+sW1vP; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf13.hostedemail.com: domain of chengming.zhou@linux.dev designates 91.218.175.171 as permitted sender) smtp.mailfrom=chengming.zhou@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1706366063; a=rsa-sha256; cv=none; b=xCOPGqQt5kG0uxLjIL/yUQDxHK0jhzYqA67sdsDAJ0z+3GXg2gaZDz0Gd/OxuUeqh6BBP6 YGUn0xp227KM5Uhyhk4u7c7pRKbN8Vs+23N1HvaiH+IBsLJEcA/nSYMDOLLTMigqxKKct5 Coc/IGIWYQtwS6vlTYpzPi/dw8anvTo= Message-ID: <76b9e52a-9b51-4e4d-93ca-24a5aa3c4dca@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1706366061; h=from:from: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; bh=ldE+n6NcSlOlUyv98rKcvvVoi59JjH0e26apZ4K5NdE=; b=xY+sW1vPLcqLgZzsSoXg8dr0ISiJPof/FCC8QysRWw3p2SZ2FqEMBVnNdRQZ9uhPfrYkLN bTI5kZuDGgbj7am2ufVQM1q/+E8Tuw8VtHKFgSOnm9NV8tuIM1+r9gAGtMPju0098LkrQa ARO9fbq9kW1T3PTP33iWofiLIhPC5bU= Date: Sat, 27 Jan 2024 22:33:49 +0800 MIME-Version: 1.0 Subject: Re: [PATCH 1/2] mm/zswap: don't return LRU_SKIP if we have dropped lru lock Content-Language: en-US To: Johannes Weiner Cc: yosryahmed@google.com, nphamcs@gmail.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Chengming Zhou References: <20240126083015.3557006-1-chengming.zhou@linux.dev> <20240126142800.GF1567330@cmpxchg.org> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Chengming Zhou In-Reply-To: <20240126142800.GF1567330@cmpxchg.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 6C79F2001A X-Stat-Signature: yh15zupbzwnzcnynyebrkxtrgp84aqfi X-HE-Tag: 1706366063-803130 X-HE-Meta: U2FsdGVkX1+ayP4Xyx6NI89904nRopXQZBFWh6GdyTmM4Msjz/rUu6+tU3IgBwSQftsgnnLCaurHUKBphJ724gczYUhUdUlVJDU2SbtCab02cp8zp5Ilm0itMsiwducwKpu06bjbg1DSxOF/lkYJ5H+OkLyxcTBHEZTqRhdiSWQcW/KII2CRSUcVjfMVXtTuA4C6d2pMQ7ekWybPmqn8Z7R4YuG1d6hDIrKY8yT7yrYno0Dy9k5C3n77MfXcLrMeItc7YU/43p1liiIXi4Cnz4vVS7aJbMkfjktwfOIsvr97bi8MQ/WAVHEeB4p31Dup9d+TxVtmkpA0zRJHhbtgioyB8qakCR5dOqVGgI+zmSDbRZcPgtLTty0/jbpMujO8ARYs3FCcPysqiUQj6HMgaTAZoNxldngU2/dvJ/10nMBn/TnMkfOIGMJpGmAWDvjvvRKeWCkNjlZS8BK9xNc1wzdOt+q6SEod3rge480rQS21/SMf4pXXH81kRauNQK/T91BEeLkBibEhWk+4DqpkVrlj/QYyOzgeytjDxBPxqJjDvzmjMAHFhVvrwLIAK5/L7dfqsfprT+TGdsV+uDyyXUBFHm7y2QyJ9CDlJJQY4rU2/hOHttLw9oCwWZ5N2xChpEZ1/W+qB2yZCT2W98cRowNy/mv9BUX39oaVSORmOEIz5UA/0p76+M0NFfzueaYV93YhrTIEwUx/55NsS4Ky+PjVu3xDb0QCNspq/EhybpaJ6PWkJuG7RrOpqMdtUaA9t1U2hu3OtFi31Qqp+vq37PULlQDOB+WRQ/s0Jm5ecm51dhy7ASJI0/PaHoEDowB8GT2rFKBqLRc1M+dtp5pjaHw4sjxmSkDgjVe6w+HbHDURTCb0SxJsHQ8QnaiwDMafyD9g462l5KdstOnBUIrCXuwa0QG6ZsNPPx7MKQFKvhZSEIq4sm19P7RPBdA/grYbBpPZk2/Ga6tpUURGigo wfZxUfcn 6IaHRkG0fUjRSB3PUVXzOm84GXy5y6bEjpTChKtKh8452yhp3MHx0/jc3OsXNFFf4kx49MPUNkMZ7mPuCwTt+R1GmqypBpKFQGBs7olZc+nmRmKw+epjOX9/g9brjosBGTiaZ+7pfMVkPr3cg8N24qViOvnksmfF+cq0U179ViPxVzJJ9O0G70DLeIMDhcimX+9hVFglOBQfRPDurUjCNSulXYW3LF0NCbx5MQV5YZ3wxG5oOdw2KTbLoXnGk/DtEQfb6 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 2024/1/26 22:28, Johannes Weiner wrote: > On Fri, Jan 26, 2024 at 08:30:14AM +0000, chengming.zhou@linux.dev wrote: >> From: Chengming Zhou >> >> LRU_SKIP can only be returned if we don't ever dropped lru lock, or >> we need to return LRU_RETRY to restart from the head of lru list. > > Good catch. Can you mention the possible consequences in the log? > > "Otherwise, the iteration might continue from a cursor position that > was freed while the locks were dropped."? Good, will do. > >> Actually we may need to introduce another LRU_STOP to really terminate >> the ongoing shrinking scan process, when we encounter a warm page >> already in the swap cache. The current list_lru implementation >> doesn't have this function to early break from __list_lru_walk_one. >> >> Fixes: b5ba474f3f51 ("zswap: shrink zswap pool based on memory pressure") >> Signed-off-by: Chengming Zhou > > Acked-by: Johannes Weiner Thanks.