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Wed, 19 Feb 2025 18:45:38 -0800 (PST) Received: from google.com ([2401:fa00:8f:203:9c92:f424:750b:8e42]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-ade415b35c6sm8018927a12.18.2025.02.19.18.45.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Feb 2025 18:45:38 -0800 (PST) Date: Thu, 20 Feb 2025 11:45:30 +0900 From: Sergey Senozhatsky To: Masami Hiramatsu Cc: Steven Rostedt , Waiman Long , Peter Zijlstra , Ingo Molnar , Will Deacon , Andrew Morton , Boqun Feng , Joel Granados , Anna Schumaker , Lance Yang , Kent Overstreet , Yongliang Gao , Tomasz Figa , Sergey Senozhatsky , linux-kernel@vger.kernel.org, Linux Memory Management List Subject: Re: [PATCH 1/2] hung_task: Show the blocker task if the task is hung on mutex Message-ID: <20250220-112040-neomutt-senozhatsky@chromium.org> References: <173997003868.2137198.9462617208992136056.stgit@mhiramat.tok.corp.google.com> <173997004932.2137198.7959507113210521328.stgit@mhiramat.tok.corp.google.com> <20250219112308.5d905680@gandalf.local.home> <0fa9dd8e-2d83-487e-bfb1-1f5d20cd9fe6@redhat.com> <20250219152435.35077ac3@gandalf.local.home> <20250220080908.fc1494f0f7c611b48fbe0f8b@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250220080908.fc1494f0f7c611b48fbe0f8b@kernel.org> X-Rspam-User: X-Rspamd-Queue-Id: D224120006 X-Stat-Signature: bs4y7prxkg1ubzffk961y9mg44s4mftm X-Rspamd-Server: rspam03 X-HE-Tag: 1740019539-979520 X-HE-Meta: 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 Z4gmdh4s 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.001760, 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 (25/02/20 08:09), Masami Hiramatsu wrote: > So something like this? > > unsigned int block_flags; > union { > struct mutex *mutex; > struct rwsem +rwsem; > struct rtmutex *rtmutex; > } blocked_on; > > enum { > BLOCKED_ON_MUTEX; > BLOCKED_ON_RWSEM; > BLOCKED_ON_RTMUTEX; > BLOCKED_ON_IO; > } block_reason; I totally like this and always wanted to have something simlar, something for all "sleepable" synchronization primitives, lightweight enough (memory and CPU usage wise) to run on consumer devices. I was thinking of a rhashtable where each entry represents "sleepable" primitive with a "owner" pointer and a list of "blocked on" tasks. But I'm sure you'll have a better idea. If I may add a couple of "wishes", can we also add: - completions (so that things like wait_for_completion and synchronize srcu get covered) - wait on bit (so that things like lock_buffer and so on get covered) 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 646D1C021B0 for ; Thu, 20 Feb 2025 03:46:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D1AC94401C6; Wed, 19 Feb 2025 22:46:23 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id CCB674401AE; Wed, 19 Feb 2025 22:46:23 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B6BDC4401C6; Wed, 19 Feb 2025 22:46:23 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 97CB24401AE for ; 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Wed, 19 Feb 2025 19:46:19 -0800 (PST) Date: Thu, 20 Feb 2025 12:46:12 +0900 From: Sergey Senozhatsky To: Sergey Senozhatsky Cc: Masami Hiramatsu , Steven Rostedt , Waiman Long , Peter Zijlstra , Ingo Molnar , Will Deacon , Andrew Morton , Boqun Feng , Joel Granados , Anna Schumaker , Lance Yang , Kent Overstreet , Yongliang Gao , Tomasz Figa , linux-kernel@vger.kernel.org, Linux Memory Management List Subject: Re: [PATCH 1/2] hung_task: Show the blocker task if the task is hung on mutex Message-ID: <20250220-112040-neomutt-senozhatsky@chromium.org> References: <173997003868.2137198.9462617208992136056.stgit@mhiramat.tok.corp.google.com> <173997004932.2137198.7959507113210521328.stgit@mhiramat.tok.corp.google.com> <20250219112308.5d905680@gandalf.local.home> <0fa9dd8e-2d83-487e-bfb1-1f5d20cd9fe6@redhat.com> <20250219152435.35077ac3@gandalf.local.home> <20250220080908.fc1494f0f7c611b48fbe0f8b@kernel.org> <20250220-112040-neomutt-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250220-112040-neomutt-senozhatsky@chromium.org> X-Rspam-User: X-Rspamd-Queue-Id: 4C3E720002 X-Stat-Signature: w14sxng194scf5sn1ywsd4hmuctww8ss X-Rspamd-Server: rspam03 X-HE-Tag: 1740023181-89448 X-HE-Meta: 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 mJVkr4Sg 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.122119, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Message-ID: <20250220034612.m63f61bTtp6Qxhgv8zrzZ9ViRNPmKSrw73SEzFCmbNU@z> On (25/02/20 11:45), Sergey Senozhatsky wrote: > If I may add a couple of "wishes", can we also add: > > - completions Actually, no, this doesn't make sense, sorry for the noise. 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Wed, 19 Feb 2025 20:19:54 -0800 (PST) Received: from google.com ([2401:fa00:8f:203:9c92:f424:750b:8e42]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2fc13ab0fe7sm12801138a91.10.2025.02.19.20.19.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Feb 2025 20:19:54 -0800 (PST) Date: Thu, 20 Feb 2025 13:19:46 +0900 From: Sergey Senozhatsky To: Waiman Long Cc: Sergey Senozhatsky , Masami Hiramatsu , Steven Rostedt , Peter Zijlstra , Ingo Molnar , Will Deacon , Andrew Morton , Boqun Feng , Joel Granados , Anna Schumaker , Lance Yang , Kent Overstreet , Yongliang Gao , Tomasz Figa , linux-kernel@vger.kernel.org, Linux Memory Management List Subject: Re: [PATCH 1/2] hung_task: Show the blocker task if the task is hung on mutex Message-ID: <20250220-112040-neomutt-senozhatsky@chromium.org> References: <173997003868.2137198.9462617208992136056.stgit@mhiramat.tok.corp.google.com> <173997004932.2137198.7959507113210521328.stgit@mhiramat.tok.corp.google.com> <20250219112308.5d905680@gandalf.local.home> <0fa9dd8e-2d83-487e-bfb1-1f5d20cd9fe6@redhat.com> <20250219152435.35077ac3@gandalf.local.home> <20250220080908.fc1494f0f7c611b48fbe0f8b@kernel.org> <20250220-112040-neomutt-senozhatsky@chromium.org> <524bd2b9-5322-4012-b1d0-b76edb84ec4f@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <524bd2b9-5322-4012-b1d0-b76edb84ec4f@redhat.com> X-Rspam-User: X-Rspamd-Queue-Id: 1D0481A0002 X-Rspamd-Server: rspam07 X-Stat-Signature: nnga9w38a811ejew9gh15wxxy1jx76y5 X-HE-Tag: 1740025195-947602 X-HE-Meta: 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 RhH+fY3e cfk/oKS2oMbe4b7yYm8fgjV6I1O5Ke22J95sOAE7nNITrfvmmDQaeXiL2h7CoY2Agbkbhi7z/SDsIN/qJkYC3QHL08YUrWpLxjneOWw9BwShRBVQP/g8xpb1nq6IiEbPqPaeVCulc8jFtkHRgHJ4vJrmf806Vy/fuwR3cbeyyGtX05v8NgzpUeDDPmbCiRQtw4DGrbSx9fjR5TjAdB64s+UZpuciekILiGfNIFZFvbBMQuSPj0Hi6EUJFc4P584EOvxUU8eR+TM8WKzpBKBfFoitkOrnntFu99cGd7w0fImulfvfnmUqlgv9SehyrSqUypcA4aXfmO1lXz8IUnegf8aEjst0wtGAl1vgs7YeAQ8qUdQ2l5KSuuXeDDhV6+RfQy6L5zQjbv5QTw6rvmG9Mp+7w18LnUeTKoucohxAHFU1fFMnZd6UJ1m4qGJ0/iC1XkCmg4uM/5Cbf9pm6EiGM2lebJze4DlnTkZjv X-Bogosity: Ham, tests=bogofilter, spamicity=0.019133, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Message-ID: <20250220041946.sLgqdDihgdl7LYLva1EMxiCnmagAjreicDB6jb6aAYk@z> On (25/02/19 22:49), Waiman Long wrote: > On 2/19/25 9:45 PM, Sergey Senozhatsky wrote: > > On (25/02/20 08:09), Masami Hiramatsu wrote: > > > So something like this? > > > > > > unsigned int block_flags; > > > union { > > > struct mutex *mutex; > > > struct rwsem +rwsem; > > > struct rtmutex *rtmutex; > > > } blocked_on; > > > > > > enum { > > > BLOCKED_ON_MUTEX; > > > BLOCKED_ON_RWSEM; > > > BLOCKED_ON_RTMUTEX; > > > BLOCKED_ON_IO; > > > } block_reason; > > I totally like this and always wanted to have something simlar, > > something for all "sleepable" synchronization primitives, lightweight > > enough (memory and CPU usage wise) to run on consumer devices. I was > > thinking of a rhashtable where each entry represents "sleepable" > > primitive with a "owner" pointer and a list of "blocked on" tasks. > > But I'm sure you'll have a better idea. > > > > If I may add a couple of "wishes", can we also add: > > - completions (so that things like wait_for_completion and > > synchronize srcu get covered) > > - wait on bit (so that things like lock_buffer and so on get covered) > > Bit lock doesn't have a owner field to track the owning task. Right, so that's why I was thinking about keeping it outside in a hashtable. A list of owners plus a list of blocked_on per "lock", be it a rwsem, or a mutex, or a bit.