From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from invmail4.hynix.com (exvmail4.skhynix.com [166.125.252.92]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 8942314AAA; Mon, 29 Jan 2024 04:21:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=166.125.252.92 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706502074; cv=none; b=O21hvGkGh1AC0260mqyRrWj7y0+UFS2YTL1xAZ+lX/6BxJD5iJ2/QpApfQR29oOzC27ms7T9VHKCk2wjfD8tKvwEmKlNyRTBqcF8VkzfrAogX+KkipSqrJBhuJ3gCwjP6nKN0Bx5Sjf2jAsRgZ8s1HbWT4C5TNF0kdNz1vnfHpo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706502074; c=relaxed/simple; bh=p9WW5tw9S4aGXrjQWbwDneSN3suFm+njtOg9nHFdRRg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=VkFQriJ8vTZDCUn5pPIfGKeDFJpmi8iUvxnlPHKY+ptx0TblM4sek4qQyFo9kvw1Nwk/az7EQ2cGMp8RmmHvWYFooKLOwusi8gABeXiLMmD28UZ8AZw6TYPFzNnukMNE/JTy5HrFz19HpjHJdfaL2Sy/sZVjXIPrsXeuxnbFplE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com; spf=pass smtp.mailfrom=sk.com; arc=none smtp.client-ip=166.125.252.92 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sk.com X-AuditID: a67dfc5b-d6dff70000001748-0b-65b727aa4de6 Date: Mon, 29 Jan 2024 13:20:52 +0900 From: Byungchul Park To: Thomas Gleixner Cc: linux-kernel@vger.kernel.org, kernel_team@skhynix.com, torvalds@linux-foundation.org, damien.lemoal@opensource.wdc.com, linux-ide@vger.kernel.org, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, will@kernel.org, rostedt@goodmis.org, joel@joelfernandes.org, sashal@kernel.org, daniel.vetter@ffwll.ch, duyuyang@gmail.com, johannes.berg@intel.com, tj@kernel.org, tytso@mit.edu, willy@infradead.org, david@fromorbit.com, amir73il@gmail.com, gregkh@linuxfoundation.org, kernel-team@lge.com, linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@kernel.org, minchan@kernel.org, hannes@cmpxchg.org, vdavydov.dev@gmail.com, sj@kernel.org, jglisse@redhat.com, dennis@kernel.org, cl@linux.com, penberg@kernel.org, rientjes@google.com, vbabka@suse.cz, ngupta@vflare.org, linux-block@vger.kernel.org, josef@toxicpanda.com, linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz, jlayton@kernel.org, dan.j.williams@intel.com, hch@infradead.org, djwong@kernel.org, dri-devel@lists.freedesktop.org, rodrigosiqueiramelo@gmail.com, melissa.srw@gmail.com, hamohammed.sa@gmail.com, 42.hyeyoo@gmail.com, chris.p.wilson@intel.com, gwan-gyeong.mun@intel.com, max.byungchul.park@gmail.com, boqun.feng@gmail.com, longman@redhat.com, hdanton@sina.com, her0gyugyu@gmail.com Subject: Re: [PATCH v11 14/26] locking/lockdep, cpu/hotplus: Use a weaker annotation in AP thread Message-ID: <20240129042052.GA64402@system.software.com> References: <20240124115938.80132-1-byungchul@sk.com> <20240124115938.80132-15-byungchul@sk.com> <87il3ggfz9.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87il3ggfz9.ffs@tglx> User-Agent: Mutt/1.9.4 (2018-02-28) X-Brightmail-Tracker: H4sIAAAAAAAAA03SX0xTVxzAcc+5f9vQ5a5DPZOXpcbgMPh/22/L5pa9eJOFzW08aTZt5EYa StWLouhcYFZT/k6IUK3oSjGlgW6OwhwT0QKBUv9Ah9UhAgo2bo1UMmabVbAbF7LMl5NPzvmd b87D4SntLLOMN5j2SbJJb9SxalodSapLb0z9WVrbMr4SKsvWQvSphYbaC24WAj80IXC3FmEI 92yG32KTCGZuDlBgrQ4gqBsfpaC1dwxBh+sbFm6FXoJgdIoFf3UpC0frL7Dw6+NZDCM1VRia PBlw/YQDgzf+Ow3WMAtnrEfx3PIHhrizkQNn4QqYcNk4mB1fB/6xOwx0DK+C0+dGWLjc4aeh t20Cw61LtSyMuf9h4HpvHw2BynIGvn/iYOFxzEmBMzrFwaDXjuFH81zo+F8JBnzlXgzHzzdj CN5tR3DF8gCDx32Hhe7oJIYWTzUFzxp6EExURDg4Vhbn4ExRBYLSYzU0DDz3MWAeeQNm/q5l P3hH7J6cokRzywGxI2anxWsOIv5iG+VE85VhTrR79ostrjSx/nIYi3XTUUb0NBazome6ihNL IkEsPunv58S+UzO0GApa8ZaUrep3sySjIV+S12zaoc4ebTuF99QkHYzcDqFCdFVVgnieCBtJ xPlxCVLN09vvQoppYQUZae2cNyukkqGhOKU4WVhJmgeH500JfjUJOD5U/Iqwk9x92MkoSY0A xOrLVKgVDpHWksXKhEZ4mfhPh+iFm2lkKBHGygglpJCGBK9sqwQdqbKYWcWLheXEe9GHFx7W riIDz0wLfpV0uoboE0iwvVC1vVC1/V+1I6oRaQ2m/Fy9wbhxdXaByXBw9c7duR409yedR2a3 taHpwOddSOCRLknDF12UtIw+P68gtwsRntIla+Kv/yRpNVn6gkOSvHu7vN8o5XWhFJ7WLdWs jx3I0gq79PukHEnaI8n/nWJetawQHb6d3rPtfqL+0aL0tyvvGbvf6jp5OHeD6VPHDcvZDHZ9 7CvQrwrLDU1b5GtrzpJ7qVtd34W2lz088tqfJ89TXyY+SmTuHXMXZ/LqtD5fOZ/y9dPS9h0V S5ds+uwTO725UkwO5uieNz/a0GB5kOH9dtKUfen+8pzim4NfvBnf+7686L0+HZ2XrV+XRsl5 +n8BEUqc/48DAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA02Sa0yTZxTH8zzvtQ0lrxXYo/ipTkG8YaLLibhF/aDv3OZGojFRozT6Co2A rkUUExIYlSCoERKoVsZqWQqpKFAK4gWsEKnVCAgMCgGErskkXOrUEisXpS6Lfjn55Zz/73z6 85RyhFnKa1LTJG2qOlnFymn57rictdao21LsG4sMCi/Egv9tHg2l1VUsdN66gaDKno1h7NFO 6JueQDDzrIMCQ3EnguujQxTY24YRNFX+xkK3NxR6/D4WXMUFLOSUV7PwfHwWw2BJEYYbtp/g 6WUzBkfgHxoMYyxcM+TghfESQ8Bi5cCStQI8lUYOZkc3gGu4l4HW310MNA2shqtlgyzcb3LR 0NbowdB9t5SF4aoPDDxte0xDZ+FFBm5OmVkYn7ZQYPH7OOhymDDU6Be+5b6ZZ8B50YEh989a DD399xA0541gsFX1stDqn8BQZyum4H3FIwSeS5McnLsQ4OBa9iUEBedKaOiYczKgH9wEM+9K 2a1xYuuEjxL1dafFpmkTLT4xE/GOcYgT9c0DnGiynRLrKmPE8vtjWLz+2s+INut5VrS9LuLE /MkeLE61t3Pi4ysztOjtMeBflu2XbzkqJWvSJe367xLkSUONV/DJkpAzk395URZ6IMtHMp4I G4mjvRIFmRZWkEH7w0/MClHE7Q5QQQ4Toklt18AnpgSXnHSatwd5sXCE9P/9kMlHPK8QgBic e4KoFM4Se354MKEQFhHXVS/9nxlD3PNjOBihhEhSMc8H1zJBRYry9GyQw4XlxNHgxJeRwviF bfzCNn62TYiyojBNanqKWpO8aZ3ueFJGqubMuiMnUmxooXeWzNnCRvS2e2cLEnikClHw2Q2S klGn6zJSWhDhKVWYIrCqXlIqjqozzkraE4e1p5IlXQuK5GnVV4pd+6QEpZCoTpOOS9JJSfv/ FfOypVloZKo36vupkPXfeGIjVptDk0aWGH/enrtSxTpNZfrMgh3NOS1r+m/nJe4vT9y1dWOM sa/NF+F17/3aExh99e2vpbM/krK4FxQ3PncgdN/40Olw/qD935cHK87X/LDZF71neeSh+giT fnrzIqPc3Vf3R/zetDlr5q2MgdoXo8fiNQnblqhoXZJ6Qwyl1ak/AnGPtF9zAwAA X-CFilter-Loop: Reflected On Fri, Jan 26, 2024 at 06:30:02PM +0100, Thomas Gleixner wrote: > On Wed, Jan 24 2024 at 20:59, Byungchul Park wrote: > > Why is lockdep in the subsystem prefix here? You are changing the CPU > hotplug (not hotplus) code, right? I will fix the typo ;( Thank you. I referred to the commit cb92173d1f047. I will remove the prefix if the way is more desirable. > > cb92173d1f0 ("locking/lockdep, cpu/hotplug: Annotate AP thread") was > > introduced to make lockdep_assert_cpus_held() work in AP thread. > > > > However, the annotation is too strong for that purpose. We don't have to > > use more than try lock annotation for that. > > This lacks a proper explanation why this is too strong. rwsem_acquire() implies: 1. might be a waiter on contention of the lock. 2. enter to the critical section of the lock. All we need in here is to act 2, not 1. That's why I suggested trylock version of annotation for that purpose. Now that dept partially replies on lockdep annotaions for the waiters and events, dept is interpeting rwsem_acquire() as a potential waiter and reports a deadlock by the wait. Of course, the first priority should be not to change the current behavior. I think the change from non-trylock to trylock for the annotation won't. Or am I missing something? Byungchul > > Furthermore, now that Dept was introduced, false positive alarms was > > reported by that. Replaced it with try lock annotation. > > I still have zero idea what this is about. > > Thanks, > > tglx