From: Bart Van Assche <Bart.VanAssche@wdc.com>
To: "byungchul.park@lge.com" <byungchul.park@lge.com>
Cc: "mingo@kernel.org" <mingo@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"peterz@infradead.org" <peterz@infradead.org>,
"hch@infradead.org" <hch@infradead.org>,
"amir73il@gmail.com" <amir73il@gmail.com>,
"linux-xfs@vger.kernel.org" <linux-xfs@vger.kernel.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"oleg@redhat.com" <oleg@redhat.com>,
"darrick.wong@oracle.com" <darrick.wong@oracle.com>,
"johannes.berg@intel.com" <johannes.berg@intel.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"idryomov@gmail.com" <idryomov@gmail.com>,
"tj@kernel.org" <tj@kernel.org>,
"kernel-team@lge.com" <kernel-team@lge.com>,
"david@fromorbit.com" <david@fromorbit.com>
Subject: Re: Fix false positive by LOCKDEP_CROSSRELEASE
Date: Thu, 19 Oct 2017 14:52:56 +0000 [thread overview]
Message-ID: <1508424774.2429.1.camel@wdc.com> (raw)
In-Reply-To: <20171019015705.GD32368@X58A-UD3R>
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cnQu
WARNING: multiple messages have this Message-ID (diff)
From: Bart Van Assche <Bart.VanAssche@wdc.com>
To: "byungchul.park@lge.com" <byungchul.park@lge.com>
Cc: "mingo@kernel.org" <mingo@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"peterz@infradead.org" <peterz@infradead.org>,
"hch@infradead.org" <hch@infradead.org>,
"amir73il@gmail.com" <amir73il@gmail.com>,
"linux-xfs@vger.kernel.org" <linux-xfs@vger.kernel.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"oleg@redhat.com" <oleg@redhat.com>,
"darrick.wong@oracle.com" <darrick.wong@oracle.com>,
"johannes.berg@intel.com" <johannes.berg@intel.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"idryomov@gmail.com" <idryomov@gmail.com>,
"tj@kernel.org" <tj@kernel.org>,
"kernel-team@lge.com" <kernel-team@lge.com>,
"david@fromorbit.com" <david@fromorbit.com>
Subject: Re: Fix false positive by LOCKDEP_CROSSRELEASE
Date: Thu, 19 Oct 2017 14:52:56 +0000 [thread overview]
Message-ID: <1508424774.2429.1.camel@wdc.com> (raw)
In-Reply-To: <20171019015705.GD32368@X58A-UD3R>
On Thu, 2017-10-19 at 10:57 +0900, Byungchul Park wrote:
> On Wed, Oct 18, 2017 at 02:29:56PM +0000, Bart Van Assche wrote:
> > On Wed, 2017-10-18 at 18:38 +0900, Byungchul Park wrote:
> > > Several false positives were reported, so I tried to fix them.
> > >
> > > It would be appreciated if you tell me if it works as expected, or let
> > > me know your opinion.
> >
> > What I have been wondering about is whether the crosslock checking makes
> > sense from a conceptual point of view. I tried to find documentation for the
> > crosslock checking in Documentation/locking/lockdep-design.txt but
> > couldn't find a description of the crosslock checking. Shouldn't it be
> > documented somewhere what the crosslock checks do and what the theory is
> > behind these checks?
>
> Documentation/locking/crossrelease.txt would be helpful.
That document is incomplete. It does not mention that although it can be
proven that the traditional lock validation code won't produce false
positives, that the cross-release checks do not have a solid theoretical
foundation and are prone to produce false positive reports.
Bart.
WARNING: multiple messages have this Message-ID (diff)
From: Bart Van Assche <Bart.VanAssche@wdc.com>
To: "byungchul.park@lge.com" <byungchul.park@lge.com>
Cc: "mingo@kernel.org" <mingo@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"peterz@infradead.org" <peterz@infradead.org>,
"hch@infradead.org" <hch@infradead.org>,
"amir73il@gmail.com" <amir73il@gmail.com>,
"linux-xfs@vger.kernel.org" <linux-xfs@vger.kernel.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"oleg@redhat.com" <oleg@redhat.com>,
"darrick.wong@oracle.com" <darrick.wong@oracle.com>,
"johannes.berg@intel.com" <johannes.berg@intel.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"idryomov@gmail.com" <idryomov@gmail.com>,
"tj@kernel.org" <tj@kernel.org>,
"kernel-team@lge.com" <kernel-team@lge.com>,
"david@fromorbit.com" <david@fromorbit.com>
Subject: Re: Fix false positive by LOCKDEP_CROSSRELEASE
Date: Thu, 19 Oct 2017 14:52:56 +0000 [thread overview]
Message-ID: <1508424774.2429.1.camel@wdc.com> (raw)
In-Reply-To: <20171019015705.GD32368@X58A-UD3R>
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="utf-8", Size: 1242 bytes --]
On Thu, 2017-10-19 at 10:57 +0900, Byungchul Park wrote:
> On Wed, Oct 18, 2017 at 02:29:56PM +0000, Bart Van Assche wrote:
> > On Wed, 2017-10-18 at 18:38 +0900, Byungchul Park wrote:
> > > Several false positives were reported, so I tried to fix them.
> > >
> > > It would be appreciated if you tell me if it works as expected, or let
> > > me know your opinion.
> >
> > What I have been wondering about is whether the crosslock checking makes
> > sense from a conceptual point of view. I tried to find documentation for the
> > crosslock checking in Documentation/locking/lockdep-design.txt but
> > couldn't find a description of the crosslock checking. Shouldn't it be
> > documented somewhere what the crosslock checks do and what the theory is
> > behind these checks?
>
> Documentation/locking/crossrelease.txt would be helpful.
That document is incomplete. It does not mention that although it can be
proven that the traditional lock validation code won't produce false
positives, that the cross-release checks do not have a solid theoretical
foundation and are prone to produce false positive reports.
Bart.N‹§²æìr¸›zǧu©ž²Æ {\b†éì¹»\x1c®&Þ–)îÆi¢žØ^n‡r¶‰šŽŠÝ¢j$½§$¢¸\x05¢¹¨è§~Š'.)îÄÃ,yèm¶ŸÿÃ\f%Š{±šj+ƒðèž×¦j)Z†·Ÿ
next prev parent reply other threads:[~2017-10-19 14:52 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-18 9:38 Fix false positive by LOCKDEP_CROSSRELEASE Byungchul Park
2017-10-18 9:38 ` Byungchul Park
2017-10-18 9:38 ` [RESEND PATCH 1/3] completion: Add support for initializing completion with lockdep_map Byungchul Park
2017-10-18 9:38 ` Byungchul Park
2017-10-19 23:24 ` Bart Van Assche
2017-10-19 23:24 ` Bart Van Assche
2017-10-20 6:14 ` Byungchul Park
2017-10-20 6:14 ` Byungchul Park
2017-10-20 6:34 ` Thomas Gleixner
2017-10-20 6:34 ` Thomas Gleixner
2017-10-20 19:58 ` Bart Van Assche
2017-10-20 19:58 ` Bart Van Assche
2017-10-20 19:58 ` Bart Van Assche
2017-10-21 2:23 ` Byungchul Park
2017-10-21 2:23 ` Byungchul Park
2017-10-22 14:34 ` Bart Van Assche
2017-10-22 14:34 ` Bart Van Assche
2017-10-23 2:08 ` Byungchul Park
2017-10-23 2:08 ` Byungchul Park
2017-10-25 7:07 ` Bart Van Assche
2017-10-25 7:07 ` Bart Van Assche
2017-10-25 11:49 ` Byungchul Park
2017-10-25 11:49 ` Byungchul Park
2017-10-18 9:38 ` [RESEND PATCH 2/3] lockdep: Remove unnecessary acquisitions wrt workqueue flush Byungchul Park
2017-10-18 9:38 ` Byungchul Park
2017-10-18 9:38 ` [RESEND PATCH 3/3] lockdep: Assign a lock_class per gendisk used for wait_for_completion() Byungchul Park
2017-10-18 9:38 ` Byungchul Park
2017-10-18 9:59 ` Ingo Molnar
2017-10-18 9:59 ` Ingo Molnar
2017-10-19 1:57 ` Byungchul Park
2017-10-19 1:57 ` Byungchul Park
2017-10-18 14:29 ` Fix false positive by LOCKDEP_CROSSRELEASE Bart Van Assche
2017-10-18 14:29 ` Bart Van Assche
2017-10-19 1:57 ` Byungchul Park
2017-10-19 1:57 ` Byungchul Park
2017-10-19 14:52 ` Bart Van Assche [this message]
2017-10-19 14:52 ` Bart Van Assche
2017-10-19 14:52 ` Bart Van Assche
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