From: Byungchul Park <byungchul.park@lge.com> To: Steven Rostedt <rostedt@goodmis.org> Cc: Theodore Ts'o <tytso@mit.edu>, 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, linux-kernel@vger.kernel.org, peterz@infradead.org, will@kernel.org, tglx@linutronix.de, joel@joelfernandes.org, sashal@kernel.org, daniel.vetter@ffwll.ch, chris@chris-wilson.co.uk, duyuyang@gmail.com, johannes.berg@intel.com, tj@kernel.org, willy@infradead.org, david@fromorbit.com, amir73il@gmail.com, bfields@fieldses.org, 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, axboe@kernel.dk, paolo.valente@linaro.org, josef@toxicpanda.com, linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz, jack@suse.com, jlayton@kernel.org, dan.j.williams@intel.com, hch@infradead.org, djwong@kernel.org, dri-devel@lists.freedesktop.org, airlied@linux.ie, rodrigosiqueiramelo@gmail.com, melissa.srw@gmail.com, hamohammed.sa@gmail.com Subject: Re: [PATCH 00/16] DEPT(Dependency Tracker) Date: Sat, 19 Feb 2022 19:18:20 +0900 [thread overview] Message-ID: <20220219101820.GC10342@X58A-UD3R> (raw) In-Reply-To: <20220217120005.67f5ddf4@gandalf.local.home> On Thu, Feb 17, 2022 at 12:00:05PM -0500, Steven Rostedt wrote: > On Thu, 17 Feb 2022 10:51:09 -0500 > "Theodore Ts'o" <tytso@mit.edu> wrote: > > > I know that you're trying to help us, but this tool needs to be far > > better than Lockdep before we should think about merging it. Even if > > it finds 5% more potential deadlocks, if it creates 95% more false > > positive reports --- and the ones it finds are crazy things that > > rarely actually happen in practice, are the costs worth the benefits? > > And who is bearing the costs, and who is receiving the benefits? > > I personally believe that there's potential that this can be helpful and we > will want to merge it. > > But, what I believe Ted is trying to say is, if you do not know if the > report is a bug or not, please do not ask the maintainers to determine it > for you. This is a good opportunity for you to look to see why your tool > reported an issue, and learn that subsystem. Look at if this is really a > bug or not, and investigate why. Appreciate your feedback. I'll be more careful in reporting things, and I think I need to make it more conservative... > The likely/unlikely tracing I do finds issues all over the kernel. But > before I report anything, I look at the subsystem and determine *why* it's > reporting what it does. In some cases, it's just a config issue. Where, I > may submit a patch saying "this is 100% wrong in X config, and we should > just remove the "unlikely". But I did the due diligence to find out exactly > what the issue is, and why the tooling reported what it reported. I'll try my best to do things that way. However, thing is that there's few reports with my system... That's why I shared Dept in LKML space. > I want to stress that your Dept tooling looks to have the potential of > being something that will be worth while including. But the false positives > needs to be down to the rate of lockdep false positives. As Ted said, if > it's reporting 95% false positives, nobody is going to look at the 5% of > real bugs that it finds. Agree. Dept should not be merged if so. I'm not pushing ahead, but I'm convinced that Dept works what a dependency tracker should do. Let's see how valuable it is esp. in the middle of developing something in the kernel. Thanks, Byungchul
WARNING: multiple messages have this Message-ID (diff)
From: Byungchul Park <byungchul.park@lge.com> To: Steven Rostedt <rostedt@goodmis.org> Cc: hamohammed.sa@gmail.com, jack@suse.cz, peterz@infradead.org, daniel.vetter@ffwll.ch, amir73il@gmail.com, david@fromorbit.com, dri-devel@lists.freedesktop.org, chris@chris-wilson.co.uk, bfields@fieldses.org, linux-ide@vger.kernel.org, adilger.kernel@dilger.ca, joel@joelfernandes.org, cl@linux.com, will@kernel.org, duyuyang@gmail.com, sashal@kernel.org, paolo.valente@linaro.org, damien.lemoal@opensource.wdc.com, willy@infradead.org, hch@infradead.org, airlied@linux.ie, mingo@redhat.com, djwong@kernel.org, vdavydov.dev@gmail.com, rientjes@google.com, dennis@kernel.org, linux-ext4@vger.kernel.org, linux-mm@kvack.org, ngupta@vflare.org, johannes.berg@intel.com, jack@suse.com, dan.j.williams@intel.com, josef@toxicpanda.com, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, jglisse@redhat.com, viro@zeniv.linux.org.uk, tglx@linutronix.de, mhocko@kernel.org, vbabka@suse.cz, axboe@kernel.dk, melissa.srw@gmail.com, sj@kernel.org, Theodore Ts'o <tytso@mit.edu>, rodrigosiqueiramelo@gmail.com, kernel-team@lge.com, gregkh@linuxfoundation.org, jlayton@kernel.org, linux-kernel@vger.kernel.org, penberg@kernel.org, minchan@kernel.org, hannes@cmpxchg.org, tj@kernel.org, akpm@linux-foundation.org, torvalds@linux-foundation.org Subject: Re: [PATCH 00/16] DEPT(Dependency Tracker) Date: Sat, 19 Feb 2022 19:18:20 +0900 [thread overview] Message-ID: <20220219101820.GC10342@X58A-UD3R> (raw) In-Reply-To: <20220217120005.67f5ddf4@gandalf.local.home> On Thu, Feb 17, 2022 at 12:00:05PM -0500, Steven Rostedt wrote: > On Thu, 17 Feb 2022 10:51:09 -0500 > "Theodore Ts'o" <tytso@mit.edu> wrote: > > > I know that you're trying to help us, but this tool needs to be far > > better than Lockdep before we should think about merging it. Even if > > it finds 5% more potential deadlocks, if it creates 95% more false > > positive reports --- and the ones it finds are crazy things that > > rarely actually happen in practice, are the costs worth the benefits? > > And who is bearing the costs, and who is receiving the benefits? > > I personally believe that there's potential that this can be helpful and we > will want to merge it. > > But, what I believe Ted is trying to say is, if you do not know if the > report is a bug or not, please do not ask the maintainers to determine it > for you. This is a good opportunity for you to look to see why your tool > reported an issue, and learn that subsystem. Look at if this is really a > bug or not, and investigate why. Appreciate your feedback. I'll be more careful in reporting things, and I think I need to make it more conservative... > The likely/unlikely tracing I do finds issues all over the kernel. But > before I report anything, I look at the subsystem and determine *why* it's > reporting what it does. In some cases, it's just a config issue. Where, I > may submit a patch saying "this is 100% wrong in X config, and we should > just remove the "unlikely". But I did the due diligence to find out exactly > what the issue is, and why the tooling reported what it reported. I'll try my best to do things that way. However, thing is that there's few reports with my system... That's why I shared Dept in LKML space. > I want to stress that your Dept tooling looks to have the potential of > being something that will be worth while including. But the false positives > needs to be down to the rate of lockdep false positives. As Ted said, if > it's reporting 95% false positives, nobody is going to look at the 5% of > real bugs that it finds. Agree. Dept should not be merged if so. I'm not pushing ahead, but I'm convinced that Dept works what a dependency tracker should do. Let's see how valuable it is esp. in the middle of developing something in the kernel. Thanks, Byungchul
next prev parent reply other threads:[~2022-02-19 10:18 UTC|newest] Thread overview: 134+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-02-17 10:57 [PATCH 00/16] DEPT(Dependency Tracker) Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 10:57 ` [PATCH 01/16] llist: Move llist_{head,node} definition to types.h Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 10:57 ` [PATCH 02/16] dept: Implement Dept(Dependency Tracker) Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 15:54 ` Steven Rostedt 2022-02-17 15:54 ` Steven Rostedt 2022-02-17 17:36 ` Steven Rostedt 2022-02-17 17:36 ` Steven Rostedt 2022-02-18 6:09 ` Byungchul Park 2022-02-18 6:09 ` Byungchul Park 2022-02-17 19:46 ` kernel test robot 2022-02-17 19:46 ` kernel test robot 2022-02-17 19:46 ` kernel test robot 2022-02-17 19:46 ` kernel test robot 2022-02-17 10:57 ` [PATCH 03/16] dept: Embed Dept data in Lockdep Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 10:57 ` [PATCH 04/16] dept: Apply Dept to spinlock Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 10:57 ` [PATCH 05/16] dept: Apply Dept to mutex families Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 10:57 ` [PATCH 06/16] dept: Apply Dept to rwlock Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 10:57 ` [PATCH 07/16] dept: Apply Dept to wait_for_completion()/complete() Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 19:46 ` kernel test robot 2022-02-17 19:46 ` kernel test robot 2022-02-17 10:57 ` [PATCH 08/16] dept: Apply Dept to seqlock Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 10:57 ` [PATCH 09/16] dept: Apply Dept to rwsem Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 10:57 ` [PATCH 10/16] dept: Add proc knobs to show stats and dependency graph Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 15:55 ` Steven Rostedt 2022-02-17 15:55 ` Steven Rostedt 2022-02-17 10:57 ` [PATCH 11/16] dept: Introduce split map concept and new APIs for them Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 10:57 ` [PATCH 12/16] dept: Apply Dept to wait/event of PG_{locked,writeback} Byungchul Park 2022-02-17 10:57 ` [PATCH 12/16] dept: Apply Dept to wait/event of PG_{locked, writeback} Byungchul Park 2022-02-17 10:57 ` [PATCH 13/16] dept: Apply SDT to swait Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 10:57 ` [PATCH 14/16] dept: Apply SDT to wait(waitqueue) Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 10:57 ` [PATCH 15/16] locking/lockdep, cpu/hotplus: Use a weaker annotation in AP thread Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 10:57 ` [PATCH 16/16] dept: Distinguish each syscall context from another Byungchul Park 2022-02-17 10:57 ` Byungchul Park 2022-02-17 11:10 ` Report 1 in ext4 and journal based on v5.17-rc1 Byungchul Park 2022-02-17 11:10 ` Byungchul Park 2022-02-17 11:10 ` Report 2 " Byungchul Park 2022-02-17 11:10 ` Byungchul Park 2022-02-21 19:02 ` Jan Kara 2022-02-21 19:02 ` Jan Kara 2022-02-23 0:35 ` Byungchul Park 2022-02-23 0:35 ` Byungchul Park 2022-02-23 14:48 ` Jan Kara 2022-02-23 14:48 ` Jan Kara 2022-02-24 1:11 ` Byungchul Park 2022-02-24 1:11 ` Byungchul Park 2022-02-24 10:22 ` Jan Kara 2022-02-24 10:22 ` Jan Kara 2022-02-28 9:28 ` Byungchul Park 2022-02-28 9:28 ` Byungchul Park 2022-02-28 10:14 ` Jan Kara 2022-02-28 10:14 ` Jan Kara 2022-02-28 21:25 ` Theodore Ts'o 2022-02-28 21:25 ` Theodore Ts'o 2022-03-03 1:36 ` Byungchul Park 2022-03-03 1:36 ` Byungchul Park 2022-03-03 1:00 ` Byungchul Park 2022-03-03 1:00 ` Byungchul Park 2022-03-03 2:32 ` Theodore Ts'o 2022-03-03 2:32 ` Theodore Ts'o 2022-03-03 5:23 ` Byungchul Park 2022-03-03 5:23 ` Byungchul Park 2022-03-03 14:36 ` Theodore Ts'o 2022-03-03 14:36 ` Theodore Ts'o 2022-03-04 0:42 ` Byungchul Park 2022-03-04 0:42 ` Byungchul Park 2022-03-05 3:26 ` Theodore Ts'o 2022-03-05 3:26 ` Theodore Ts'o 2022-03-05 14:15 ` Byungchul Park 2022-03-05 14:15 ` Byungchul Park 2022-03-05 15:05 ` Joel Fernandes 2022-03-05 15:05 ` Joel Fernandes 2022-03-07 2:43 ` Byungchul Park 2022-03-07 2:43 ` Byungchul Park 2022-03-04 3:20 ` Byungchul Park 2022-03-04 3:20 ` Byungchul Park 2022-03-05 3:40 ` Theodore Ts'o 2022-03-05 3:40 ` Theodore Ts'o 2022-03-05 14:55 ` Byungchul Park 2022-03-05 14:55 ` Byungchul Park 2022-03-05 15:12 ` Reimar Döffinger 2022-03-05 15:12 ` Reimar Döffinger 2022-03-06 3:30 ` Theodore Ts'o 2022-03-06 3:30 ` Theodore Ts'o 2022-03-06 10:51 ` Byungchul Park 2022-03-06 10:51 ` Byungchul Park 2022-03-06 14:19 ` Theodore Ts'o 2022-03-06 14:19 ` Theodore Ts'o 2022-03-10 1:45 ` Byungchul Park 2022-03-10 1:45 ` Byungchul Park 2022-03-03 9:54 ` Jan Kara 2022-03-03 9:54 ` Jan Kara 2022-03-04 1:56 ` Byungchul Park 2022-03-04 1:56 ` Byungchul Park 2022-02-17 13:27 ` Report 1 " Matthew Wilcox 2022-02-17 13:27 ` Matthew Wilcox 2022-02-18 0:41 ` Byungchul Park 2022-02-18 0:41 ` Byungchul Park 2022-02-22 8:27 ` Jan Kara 2022-02-22 8:27 ` Jan Kara 2022-02-23 1:40 ` Byungchul Park 2022-02-23 1:40 ` Byungchul Park 2022-02-23 3:30 ` Byungchul Park 2022-02-23 3:30 ` Byungchul Park 2022-02-17 15:51 ` [PATCH 00/16] DEPT(Dependency Tracker) Theodore Ts'o 2022-02-17 15:51 ` Theodore Ts'o 2022-02-17 17:00 ` Steven Rostedt 2022-02-17 17:00 ` Steven Rostedt 2022-02-17 17:06 ` Matthew Wilcox 2022-02-17 17:06 ` Matthew Wilcox 2022-02-19 10:05 ` Byungchul Park 2022-02-19 10:05 ` Byungchul Park 2022-02-18 4:19 ` Theodore Ts'o 2022-02-18 4:19 ` Theodore Ts'o 2022-02-19 10:34 ` Byungchul Park 2022-02-19 10:34 ` Byungchul Park 2022-02-19 10:18 ` Byungchul Park [this message] 2022-02-19 10:18 ` Byungchul Park 2022-02-19 9:54 ` Byungchul Park 2022-02-19 9:54 ` Byungchul Park
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