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(was: DEPT v18) To: Byungchul Park , linux-kernel@vger.kernel.org Cc: 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, tglx@linutronix.de, 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, 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, harry.yoo@oracle.com, chris.p.wilson@intel.com, gwan-gyeong.mun@intel.com, max.byungchul.park@gmail.com, boqun.feng@gmail.com, longman@redhat.com, yunseong.kim@ericsson.com, ysk@kzalloc.com, yeoreum.yun@arm.com, netdev@vger.kernel.org, matthew.brost@intel.com, her0gyugyu@gmail.com, corbet@lwn.net, catalin.marinas@arm.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, luto@kernel.org, sumit.semwal@linaro.org, gustavo@padovan.org, christian.koenig@amd.com, andi.shyti@kernel.org, arnd@arndb.de, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, rppt@kernel.org, surenb@google.com, mcgrof@kernel.org, petr.pavlu@suse.com, da.gomez@kernel.org, samitolvanen@google.com, paulmck@kernel.org, frederic@kernel.org, neeraj.upadhyay@kernel.org, joelagnelf@nvidia.com, josh@joshtriplett.org, urezki@gmail.com, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, qiang.zhang@linux.dev, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, chuck.lever@oracle.com, neil@brown.name, okorniev@redhat.com, Dai.Ngo@oracle.com, tom@talpey.com, trondmy@kernel.org, anna@kernel.org, kees@kernel.org, bigeasy@linutronix.de, clrkwllms@kernel.org, mark.rutland@arm.com, ada.coupriediaz@arm.com, kristina.martsenko@arm.com, wangkefeng.wang@huawei.com, broonie@kernel.org, kevin.brodsky@arm.com, dwmw@amazon.co.uk, shakeel.butt@linux.dev, ast@kernel.org, ziy@nvidia.com, yuzhao@google.com, baolin.wang@linux.alibaba.com, usamaarif642@gmail.com, joel.granados@kernel.org, richard.weiyang@gmail.com, geert+renesas@glider.be, tim.c.chen@linux.intel.com, linux@treblig.org, alexander.shishkin@linux.intel.com, lillian@star-ark.net, chenhuacai@kernel.org, francesco@valla.it, guoweikang.kernel@gmail.com, link@vivo.com, jpoimboe@kernel.org, masahiroy@kernel.org, brauner@kernel.org, thomas.weissschuh@linutronix.de, oleg@redhat.com, mjguzik@gmail.com, andrii@kernel.org, wangfushuai@baidu.com, linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-i2c@vger.kernel.org, linux-arch@vger.kernel.org, linux-modules@vger.kernel.org, rcu@vger.kernel.org, linux-nfs@vger.kernel.org, linux-rt-devel@lists.linux.dev, 2407018371@qq.com, dakr@kernel.org, miguel.ojeda.sandonis@gmail.com, neilb@ownmail.net, bagasdotme@gmail.com, wsa+renesas@sang-engineering.com, dave.hansen@intel.com, geert@linux-m68k.org, ojeda@kernel.org, alex.gaynor@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, lossin@kernel.org, a.hindborg@kernel.org, aliceryhl@google.com, tmgross@umich.edu, rust-for-linux@vger.kernel.org, Chris Mason , Roman Gushchin , Josef Bacik References: <20251205071855.72743-1-byungchul@sk.com> Content-Language: en-US In-Reply-To: <20251205071855.72743-1-byungchul@sk.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 3462018000C X-Rspam-User: X-Stat-Signature: t7xyz1jhnqss6jcna7srgcjp8gbexuis X-HE-Tag: 1779539610-733601 X-HE-Meta: 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 +1ZhHmZ1 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Can we start DEPT as an AI review prompt, by documenting DEPT's dependency tracking model and false positive elimination rules as a carefully crafted prompt? While DEPT can identify deadlock issues beyond lockdep's capabilities, it is hard to enable in automated testing; without fine-grained annotations it can produce a high rate of false positives, and verifying them requires significant human effort. The open source AI Review Prompt has locking.md file [1] that teaches the AI how to review locks and detect misuse. If we can write a review prompt for DEPT in a similar manner and have the AI do the deadlock detection and false positive elimination, I think we could identify those problems more effectively with much less human effort. [1] https://github.com/masoncl/review-prompts/blob/main/kernel/subsystem/locking.md -- Cheers, Harry / Hyeonggon On 12/5/25 4:18 PM, Byungchul Park wrote: > I'm happy to see that DEPT reported real problems in practice: > > https://lore.kernel.org/lkml/6383cde5-cf4b-facf-6e07-1378a485657d@I-love.SAKURA.ne.jp/ > https://lore.kernel.org/lkml/1674268856-31807-1-git-send-email-byungchul.park@lge.com/ > https://lore.kernel.org/all/b6e00e77-4a8c-4e05-ab79-266bf05fcc2d@igalia.com/ > > I’ve added documentation describing DEPT — this should help you > understand what DEPT is and how it works. You can use DEPT simply by > enabling CONFIG_DEPT and checking dmesg at runtime. > --- > > Hi Linus and folks, > > I’ve been developing a tool to detect deadlock possibilities by tracking > waits/events — rather than lock acquisition order — to cover all the > synchronization mechanisms. To summarize the design rationale, starting > from the problem statement, through analysis, to the solution: > > CURRENT STATUS > -------------- > Lockdep tracks lock acquisition order to identify deadlock conditions. > Additionally, it tracks IRQ state changes — via {en,dis}able — to > detect cases where locks are acquired unintentionally during > interrupt handling. > > PROBLEM > ------- > Waits and their associated events that are never reachable can > eventually lead to deadlocks. However, since Lockdep focuses solely > on lock acquisition order, it has inherent limitations when handling > waits and events. > > Moreover, by tracking only lock acquisition order, Lockdep cannot > properly handle read locks or cross-event scenarios — such as > wait_for_completion() and complete() — making it increasingly > inadequate as a general-purpose deadlock detection tool. > > SOLUTION > -------- > Once again, waits and their associated events that are never > reachable can eventually lead to deadlocks. The new solution, DEPT, > focuses directly on waits and events. DEPT monitors waits and events, > and reports them when any become unreachable. > > DEPT provides: > > * Correct handling of read locks. > * Support for general waits and events. > * Continuous operation, even after multiple reports. > * Simple, intuitive annotation APIs. > > There are still false positives, and some are already being worked on > for suppression. Especially splitting the folio class into several > appropriate classes e.g. block device mapping class and regular file > mapping class, is currently under active development by me and Yeoreum > Yun. >> Anyway, these efforts will need to continue for a while, as we’ve seen > with lockdep over two decades. DEPT is tagged as EXPERIMENTAL in > Kconfig — meaning it’s not yet suitable for use as an automation tool. > > However, for those who are interested in using DEPT to analyze complex > synchronization patterns and extract dependency insights, DEPT would be > a great tool for the purpose.