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From: Byungchul Park <byungchul.park@lge.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: torvalds@linux-foundation.org, peterz@infradead.org,
	mingo@redhat.com, will@kernel.org, linux-kernel@vger.kernel.org,
	tglx@linutronix.de, rostedt@goodmis.org, joel@joelfernandes.org,
	alexander.levin@microsoft.com, daniel.vetter@ffwll.ch,
	chris@chris-wilson.co.uk, duyuyang@gmail.com,
	johannes.berg@intel.com, tj@kernel.org, tytso@mit.edu,
	willy@infradead.org, david@fromorbit.com, amir73il@gmail.com,
	bfields@fieldses.org, gregkh@linuxfoundation.org,
	kernel-team@lge.com
Subject: Re: [RFC] Are you good with Lockdep?
Date: Thu, 12 Nov 2020 17:51:14 +0900	[thread overview]
Message-ID: <20201112085114.GC14554@X58A-UD3R> (raw)
In-Reply-To: <20201112061532.GA14554@X58A-UD3R>

On Thu, Nov 12, 2020 at 03:15:32PM +0900, Byungchul Park wrote:
> > If on the other hand there's some bug in lockdep itself that causes 
> > excessive false positives, it's better to limit the number of reports 
> > to one per bootup, so that it's not seen as a nuisance debugging 
> > facility.
> > 
> > Or if lockdep gets extended that causes multiple previously unreported 
> > (but very much real) bugs to be reported, it's *still* better to 
> > handle them one by one: because lockdep doesn't know whether it's real 
> 
> Why do you think we cannot handle them one by one with multi-reporting?
> We can handle them with the first one as we do with single-reporting.
> And also that's how we work, for example, when building the kernel or
> somethinig.

Let me add a little bit more. I just said the fact that we are able to
handle the bugs one by one as if we do with single-reporting.

But the thing is multi-reporting could be more useful in some cases.
More precisely speaking, bugs not caused by IRQ state will be reported
without annoying nuisance. I bet you have experienced a ton of nuisances
when multi-reporting Lockdep detected a deadlock by IRQ state.

For some cases, multi-reporting is as useful as single-reporting, while
for the other cases, multi-reporting is more useful. Then I think we
have to go with mutil-reporting if there's no technical issue.

Thanks,
Byungchul

  reply	other threads:[~2020-11-12  8:52 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-11  5:05 [RFC] Are you good with Lockdep? Byungchul Park
2020-11-11 10:54 ` Ingo Molnar
2020-11-11 14:36   ` Steven Rostedt
2020-11-11 23:16     ` Thomas Gleixner
2020-11-12  8:10       ` Byungchul Park
2020-11-12 14:26         ` Steven Rostedt
2020-11-12 14:52           ` Matthew Wilcox
2020-11-16  8:57             ` Byungchul Park
2020-11-16 15:37               ` Matthew Wilcox
2020-11-18  1:45                 ` Boqun Feng
2020-11-18  3:30                   ` Matthew Wilcox
2020-11-23 13:15                 ` Byungchul Park
2020-11-12 14:58           ` Byungchul Park
2020-11-16  9:05             ` Byungchul Park
2020-11-23 10:45               ` Byungchul Park
2020-11-12 10:32     ` Byungchul Park
2020-11-12 13:56       ` Daniel Vetter
2020-11-16  8:45         ` Byungchul Park
2020-11-12  6:15   ` Byungchul Park
2020-11-12  8:51     ` Byungchul Park [this message]
2020-11-12  9:46       ` Byungchul Park
2020-11-23 11:05 ` [RFC] Dept(Dependency Tracker) Implementation Byungchul Park
2020-11-23 11:36   ` [RFC 1/6] dept: Implement Dept(Dependency Tracker) Byungchul Park
2020-11-23 11:36     ` [RFC 2/6] dept: Apply Dept to spinlock Byungchul Park
2020-11-23 11:36     ` [RFC 3/6] dept: Apply Dept to mutex families Byungchul Park
2020-11-23 11:36     ` [RFC 4/6] dept: Apply Dept to rwlock Byungchul Park
2020-11-23 11:36     ` [RFC 5/6] dept: Apply Dept to wait_for_completion()/complete() Byungchul Park
2020-11-23 11:36     ` [RFC 6/6] dept: Assign custom dept_keys or disable to avoid false positives Byungchul Park
2020-11-23 12:29   ` [RFC] Dept(Dependency Tracker) Implementation Byungchul Park
2020-11-23 11:13 ` [RFC] Dept(Dependency Tracker) Report Example Byungchul Park
2020-11-23 12:14   ` Byungchul Park

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