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 A865ACD4857 for ; Wed, 4 Sep 2024 16:58:26 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 231908D025D; Wed, 4 Sep 2024 12:58:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1BA258D0253; Wed, 4 Sep 2024 12:58:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0333C8D025D; Wed, 4 Sep 2024 12:58:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id D52F58D0253 for ; Wed, 4 Sep 2024 12:58:25 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 7F319C0193 for ; Wed, 4 Sep 2024 16:58:25 +0000 (UTC) X-FDA: 82527664170.08.8080B50 Received: from mail-pg1-f179.google.com (mail-pg1-f179.google.com [209.85.215.179]) by imf15.hostedemail.com (Postfix) with ESMTP id 6B2BEA0028 for ; Wed, 4 Sep 2024 16:58:23 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=GYNjlPjf; dmarc=none; spf=pass (imf15.hostedemail.com: domain of groeck7@gmail.com designates 209.85.215.179 as permitted sender) smtp.mailfrom=groeck7@gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1725469079; a=rsa-sha256; cv=none; b=LGyfxQDvtiSkrUyD3AQxotGDoPwhkaP9FyeiiG1xx7DUHly6Fp6svfbt6aOlLuF9HFmUb8 kCKum+WosLO8PJyYg6FmoxU1dDRNCrfpU23gnPyrXQbTE0zsA077PcRPNB2IRWpsKnzGG8 1+WoYsxjLvcCnodbLEICZ4vJQ0xoaLM= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=GYNjlPjf; dmarc=none; spf=pass (imf15.hostedemail.com: domain of groeck7@gmail.com designates 209.85.215.179 as permitted sender) smtp.mailfrom=groeck7@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1725469079; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to: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=kMy7Qn1zaAc9/IMOhqSwwfWBQGHR6tB90Jwa2IOJx1I=; b=nyZvttng4C5Z6d+fHyTORw7GrOp/xdPEaW2I1YRAmeO8Eb75H6gfZDOAGa8Bu2UMfWlbsk NmzDbvDU6ebGc8vxVuw9Dj+C+cy6xnMQ7CcxNWIYcRmxTRhlZ/oWC0DHAn4G1ierPG+kx1 G0c9P73bVpMG0HDBZ7AxEbQ17uyJapQ= Received: by mail-pg1-f179.google.com with SMTP id 41be03b00d2f7-7cd9d408040so5100051a12.0 for ; Wed, 04 Sep 2024 09:58:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1725469102; x=1726073902; darn=kvack.org; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:to:subject:user-agent:mime-version:date :message-id:sender:from:to:cc:subject:date:message-id:reply-to; bh=kMy7Qn1zaAc9/IMOhqSwwfWBQGHR6tB90Jwa2IOJx1I=; b=GYNjlPjflo3Ctp/lA1Lh4PPGivQWXkAhe659den5ZcRUSz03pLFu9TQ/4Ivef30AdZ FssTmTsnQ/3eoOTyOnvz4cOxR0d+Jv/ERaxWnLK/t49+k9InUSX9b6Pw/00KAetph1Ym t8azUpRYMFJInh71M44yp/Z83dDoooqUnr3Y7phDSXRMRP3ZeNxlkfMsECT7jk2sR8TN 2yymV/eB8emELJ74nzZ3wCUnWDsBL138+Xa32boHSuIiJy+LmjdPjQG6QwSJ9Rk3nRg+ 0/x24VgbIfANGHU/OUZUaP+5m62h9bHg9fwuPjXDpX0D/blGmHJUQw9funt15vit77yc 77Sw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1725469102; x=1726073902; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:to:subject:user-agent:mime-version:date :message-id:sender:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=kMy7Qn1zaAc9/IMOhqSwwfWBQGHR6tB90Jwa2IOJx1I=; b=PXxea3dN09mTWkEPnIY1GXP82sWYqrl44VsVQ8A/ld23Xai78aOf8LWF85rEKZhQe+ q75KbbiQ4Twuf2TXAD3ap9nfUTOsBIGT++g9zI5PkO2X5BtCTzljD9UCWx6tM8I8h9Z0 JGK5axI2bscQCkEfMG2iMf8mte0j2xRGZKke5fk0WzBwoMZDeaacM6Jf6AOEIeUedD8N 5a5sW/tM4pbepDdk0x9wnM80QX5N7grm4uUJ6iDE/VrW9Lnn+M8LZeRG27Bq5O9wk6Mi NqpAZBhdZbSKsNEx5DqpyyDs9I7c6eLkUFZjJoRd8yHEMaEpt+/FjfhwXXtpS45/Dsd8 dsog== X-Forwarded-Encrypted: i=1; AJvYcCXbuU+g7/dM8k4rF2kgiJxLYuuaAply81/mu/YYZJLLXEN4oIQAqIR2O5XvmhcAKuRAzz3+L80apg==@kvack.org X-Gm-Message-State: AOJu0YxySlVFKa8FJgf8X3SXzI5/c4VUvpiojrb1LoalQo8kQnLrtRjn dLXyH+J5j9OMn42szVPhCkqlKEkF5nPRcxrvxxzxclAoLKyJFf2g X-Google-Smtp-Source: AGHT+IG7/Tr7YqkobZcAU6j60F1cDj8e4643TsFFFzLwxv/IlYTNIaaf7jDZFBtBeELj1S/3WakAeg== X-Received: by 2002:a05:6a21:3405:b0:1cc:e4be:5fae with SMTP id adf61e73a8af0-1cecf49ae7amr15745012637.7.1725469102108; Wed, 04 Sep 2024 09:58:22 -0700 (PDT) Received: from ?IPV6:2600:1700:e321:62f0:329c:23ff:fee3:9d7c? ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7177853338asm1834607b3a.58.2024.09.04.09.58.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Sep 2024 09:58:21 -0700 (PDT) Message-ID: <78880ac2-f7fe-4dc1-b2cb-25942fb0cacf@roeck-us.net> Date: Wed, 4 Sep 2024 09:58:20 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/damon/tests/vaddr-kunit: don't use mas_lock for MM_MT_FLAGS-initialized maple tree To: "Liam R. Howlett" , SeongJae Park , Andrew Morton , "Matthew Wilcox (Oracle)" , David Hildenbrand , Brendan Higgins , David Gow , damon@lists.linux.dev, linux-mm@kvack.org, kunit-dev@googlegroups.com, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org References: <20240904005815.1388-1-sj@kernel.org> <20240904011840.973-1-sj@kernel.org> <54zu64vxrhdxr4wtmwbewga44shu4f7lz4ffx2hxhag46b56hn@qgrgfrb6mhbv> Content-Language: en-US From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; keydata= xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAlVcphcFCRmg06EACgkQyx8mb86fmYFg0RAA nzXJzuPkLJaOmSIzPAqqnutACchT/meCOgMEpS5oLf6xn5ySZkl23OxuhpMZTVX+49c9pvBx hpvl5bCWFu5qC1jC2eWRYU+aZZE4sxMaAGeWenQJsiG9lP8wkfCJP3ockNu0ZXXAXwIbY1O1 c+l11zQkZw89zNgWgKobKzrDMBFOYtAh0pAInZ9TSn7oA4Ctejouo5wUugmk8MrDtUVXmEA9 7f9fgKYSwl/H7dfKKsS1bDOpyJlqhEAH94BHJdK/b1tzwJCFAXFhMlmlbYEk8kWjcxQgDWMu GAthQzSuAyhqyZwFcOlMCNbAcTSQawSo3B9yM9mHJne5RrAbVz4TWLnEaX8gA5xK3uCNCeyI sqYuzA4OzcMwnnTASvzsGZoYHTFP3DQwf2nzxD6yBGCfwNGIYfS0i8YN8XcBgEcDFMWpOQhT Pu3HeztMnF3HXrc0t7e5rDW9zCh3k2PA6D2NV4fews9KDFhLlTfCVzf0PS1dRVVWM+4jVl6l HRIAgWp+2/f8dx5vPc4Ycp4IsZN0l1h9uT7qm1KTwz+sSl1zOqKD/BpfGNZfLRRxrXthvvY8 BltcuZ4+PGFTcRkMytUbMDFMF9Cjd2W9dXD35PEtvj8wnEyzIos8bbgtLrGTv/SYhmPpahJA l8hPhYvmAvpOmusUUyB30StsHIU2LLccUPPOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAlVcpi8FCRmg08MACgkQyx8mb86fmYHNRQ/+ J0OZsBYP4leJvQF8lx9zif+v4ZY/6C9tTcUv/KNAE5leyrD4IKbnV4PnbrVhjq861it/zRQW cFpWQszZyWRwNPWUUz7ejmm9lAwPbr8xWT4qMSA43VKQ7ZCeTQJ4TC8kjqtcbw41SjkjrcTG wF52zFO4bOWyovVAPncvV9eGA/vtnd3xEZXQiSt91kBSqK28yjxAqK/c3G6i7IX2rg6pzgqh hiH3/1qM2M/LSuqAv0Rwrt/k+pZXE+B4Ud42hwmMr0TfhNxG+X7YKvjKC+SjPjqp0CaztQ0H nsDLSLElVROxCd9m8CAUuHplgmR3seYCOrT4jriMFBtKNPtj2EE4DNV4s7k0Zy+6iRQ8G8ng QjsSqYJx8iAR8JRB7Gm2rQOMv8lSRdjva++GT0VLXtHULdlzg8VjDnFZ3lfz5PWEOeIMk7Rj trjv82EZtrhLuLjHRCaG50OOm0hwPSk1J64R8O3HjSLdertmw7eyAYOo4RuWJguYMg5DRnBk WkRwrSuCn7UG+qVWZeKEsFKFOkynOs3pVbcbq1pxbhk3TRWCGRU5JolI4ohy/7JV1TVbjiDI HP/aVnm6NC8of26P40Pg8EdAhajZnHHjA7FrJXsy3cyIGqvg9os4rNkUWmrCfLLsZDHD8FnU mDW4+i+XlNFUPUYMrIKi9joBhu18ssf5i5Q= In-Reply-To: <54zu64vxrhdxr4wtmwbewga44shu4f7lz4ffx2hxhag46b56hn@qgrgfrb6mhbv> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 6B2BEA0028 X-Rspamd-Server: rspam01 X-Stat-Signature: 13eh13pff1dscnaqffq35n4xkpwnpk9m X-HE-Tag: 1725469103-937290 X-HE-Meta: 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 +jaWNHD5 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 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 9/3/24 20:36, Liam R. Howlett wrote: > * Guenter Roeck [240903 22:38]: >> On 9/3/24 19:31, Liam R. Howlett wrote: >>> * SeongJae Park [240903 21:18]: >>>> On Tue, 3 Sep 2024 17:58:15 -0700 SeongJae Park wrote: >>>> >>>>> On Tue, 3 Sep 2024 20:48:53 -0400 "Liam R. Howlett" wrote: >>>>> >>>>>> * SeongJae Park [240903 20:45]: >>>>>>> damon_test_three_regions_in_vmas() initializes a maple tree with >>>>>>> MM_MT_FLAGS. The flags contains MT_FLAGS_LOCK_EXTERN, which means >>>>>>> mt_lock of the maple tree will not be used. And therefore the maple >>>>>>> tree initialization code skips initialization of the mt_lock. However, >>>>>>> __link_vmas(), which adds vmas for test to the maple tree, uses the >>>>>>> mt_lock. In other words, the uninitialized spinlock is used. The >>>>>>> problem becomes celar when spinlock debugging is turned on, since it >>>>>>> reports spinlock bad magic bug. Fix the issue by not using the mt_lock >>>>>>> as promised. >>>>>> >>>>>> You can't do this, lockdep will tell you this is wrong. >>>>> >>>>> Hmm, but lockdep was silence on my setup? >>>>> >>>>>> We need a lock and to use the lock for writes. >>>>> >>>>> This code is executed by a single-thread test code. Do we still need the lock? >>>>> >>>>>> >>>>>> I'd suggest using different flags so the spinlock is used. >>>>> >>>>> The reporter mentioned simply dropping MT_FLAGS_LOCK_EXTERN from the flags >>>>> causes suspicious RCU usage message. May I ask if you have a suggestion of >>>>> better flags? >>> >>> That would be the lockdep complaining, so that's good. >>> >>>> >>>> I was actually thinking replacing the mt_init_flags() with mt_init(), which >>>> same to mt_init_flags() with zero flag, like below. >>> >>> Yes. This will use the spinlock which should fix your issue, but it >>> will use a different style of maple tree. >>> >>> Perhaps use MT_FLAGS_ALLOC_RANGE to use the same type of maple tree, if >>> you ever add threading you will want the rcu flag as well >>> (MT_FLAGS_USE_RCU). >>> >>> I would recommend those two and just use the spinlock. >>> >> >> I tried that (MT_FLAGS_ALLOC_RANGE | MT_FLAGS_USE_RCU). it also triggers >> the suspicious RCU usage message. >> > > I am running ./tools/testing/kunit/kunit.py run '*damon*' --arch x86_64 --raw > with: > CONFIG_LOCKDEP=y > CONFIG_DEBUG_SPINLOCK=y > > and I don't have any issue with locking in the existing code. How do I > recreate this issue? > You should find everything needed to reproduce the problem at http://server.roeck-us.net/qemu/damon/ Please let me know if you need anything else. Thanks, Guenter