From: Byungchul Park <byungchul.park@lge.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>,
Ingo Molnar <mingo@kernel.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
LKP <lkp@01.org>, Josh Poimboeuf <jpoimboe@redhat.com>,
kernel-team@lge.com
Subject: Re: [lockdep] b09be676e0 BUG: unable to handle kernel NULL pointer dereference at 000001f2
Date: Tue, 10 Oct 2017 14:48:01 +0900 [thread overview]
Message-ID: <20171010054801.GD3323@X58A-UD3R> (raw)
In-Reply-To: <CA+55aFz2dfH69tUX4GBWmU14=uMseLd_21dAvjohOtJYnfoe7A@mail.gmail.com>
On Tue, Oct 03, 2017 at 09:57:02AM -0700, Linus Torvalds wrote:
> On Tue, Oct 3, 2017 at 9:54 AM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > Can we consider just reverting the crossrelease thing?
> >
> > The apparent stack corruption really worries me [...]
>
> Side note: I also think the thing is just broken.
>
> Any actual cross-releaser should be way more annotated than just "set
> cross to 1" in the lockdep map.
>
> The place where the release is done should simply be special.
>
> Because we should *not* encourage the whole "acquire by one context,
> release by another" as being something normal and "just set the flag
> to let lockdep know".
Could you explain it more? Please let me apply what you point out. Now,
I don't understand your intention.
> So that commit is apparently buggy, but I think it might be more
> fundamentally the wrong model too.
It would be appriciated if you let me know what is buggy wrt
crossrelease and the model, then I will do my best to fix it.
But I believe the model crossrelease uses is what lockdep should have
adopted before.
Anyway, I might be wrong. It would be appriciated if you tell me why you
think so.
Thank you.
next prev parent reply other threads:[~2017-10-10 5:48 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-03 14:06 [lockdep] b09be676e0 BUG: unable to handle kernel NULL pointer dereference at 000001f2 Fengguang Wu
2017-10-03 14:31 ` Josh Poimboeuf
2017-10-03 14:41 ` Josh Poimboeuf
2017-10-03 15:05 ` Josh Poimboeuf
2017-10-03 16:28 ` Josh Poimboeuf
2017-10-03 17:34 ` Josh Poimboeuf
2017-10-03 21:44 ` Tetsuo Handa
2017-10-04 21:06 ` Josh Poimboeuf
2017-10-04 21:30 ` Linus Torvalds
2017-10-04 22:15 ` Josh Poimboeuf
2017-10-04 22:40 ` Josh Poimboeuf
2017-10-05 11:02 ` Tetsuo Handa
2017-10-05 13:57 ` Josh Poimboeuf
2017-10-04 8:34 ` Peter Zijlstra
2017-10-10 5:57 ` Byungchul Park
2017-10-03 16:54 ` Linus Torvalds
2017-10-03 16:57 ` Linus Torvalds
2017-10-10 5:48 ` Byungchul Park [this message]
2017-10-10 16:22 ` Linus Torvalds
2017-10-10 16:56 ` Linus Torvalds
2017-10-10 18:14 ` Peter Zijlstra
2017-10-10 18:38 ` Linus Torvalds
2017-10-11 1:14 ` Byungchul Park
2017-10-11 2:36 ` Byungchul Park
2017-10-11 0:56 ` Byungchul Park
2017-10-11 1:02 ` Byungchul Park
2017-10-12 1:15 ` Byungchul Park
2017-10-03 17:18 ` Ingo Molnar
2017-10-04 9:20 ` Peter Zijlstra
2017-10-04 10:31 ` Ingo Molnar
2017-10-04 14:15 ` Josh Poimboeuf
2017-10-10 5:30 ` Byungchul Park
2017-10-05 13:01 ` Josh Poimboeuf
2017-10-05 14:54 ` Josh Poimboeuf
2017-10-09 10:50 ` Peter Zijlstra
2017-10-09 12:21 ` Fengguang Wu
2017-10-09 12:54 ` Peter Zijlstra
2017-10-09 12:59 ` Fengguang Wu
2017-10-09 13:03 ` Josh Poimboeuf
2017-10-09 12:55 ` Fengguang Wu
2017-10-09 13:26 ` Josh Poimboeuf
2017-10-09 14:17 ` Fengguang Wu
2017-10-09 15:28 ` Peter Zijlstra
2017-10-09 15:41 ` Fengguang Wu
2017-10-09 15:44 ` Peter Zijlstra
2017-10-09 15:47 ` Fengguang Wu
2017-10-10 5:08 ` Byungchul Park
2017-10-12 8:47 ` Peter Zijlstra
2017-10-12 9:21 ` Fengguang Wu
2017-10-12 9:28 ` Fengguang Wu
2017-10-12 11:45 ` Peter Zijlstra
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