From: Ingo Molnar <mingo@kernel.org>
To: lkp@lists.01.org
Subject: Re: [lockdep] b09be676e0 BUG: unable to handle kernel NULL pointer dereference at 000001f2
Date: Tue, 03 Oct 2017 19:18:24 +0200 [thread overview]
Message-ID: <20171003171824.te5cxms2hq634tvi@gmail.com> (raw)
In-Reply-To: <CA+55aFxa_1pCMt-GQmBZUzRbc8_UY9sacmEaCqkDM1_=sq8y_A@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 1515 bytes --]
* Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Tue, Oct 3, 2017 at 7:06 AM, Fengguang Wu <fengguang.wu@intel.com> wrote:
> >
> > This patch triggers a NULL-dereference bug at update_stack_state().
> > Although its parent commit also has a NULL-dereference bug, however
> > the call stack looks rather different. Both dmesg files are attached.
> >
> > It also triggers this warning, which is being discussed in another
> > thread, so CC Josh. The full dmesg attached, too.
> >
> > Please press Enter to activate this console.
> > [ 138.605622] WARNING: kernel stack regs at be299c9a in procd:340 has bad 'bp' value 000001be
> > [ 138.605627] unwind stack type:0 next_sp: (null) mask:0x2 graph_idx:0
> > [ 138.605631] be299c9a: 299ceb00 (0x299ceb00)
> > [ 138.605633] be299c9e: 2281f1be (0x2281f1be)
> > [ 138.605634] be299ca2: 299cebb6 (0x299cebb6)
> >
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> >
> > commit b09be676e0ff25bd6d2e7637e26d349f9109ad75
> > locking/lockdep: Implement the 'crossrelease' feature
>
> Can we consider just reverting the crossrelease thing?
Yes, I'll do that tomorrow. I was always a bit unhappy about cross-release,
because it breaks the 'owner task owns the lock' model. Plus I don't think
we found that many real bugs with it - in a 20+ years old, 15+ MLOC code
base that never run with such a debugging facility enabled.
Thanks,
Ingo
WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>,
Byungchul Park <byungchul.park@lge.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
LKP <lkp@01.org>, Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [lockdep] b09be676e0 BUG: unable to handle kernel NULL pointer dereference at 000001f2
Date: Tue, 3 Oct 2017 19:18:24 +0200 [thread overview]
Message-ID: <20171003171824.te5cxms2hq634tvi@gmail.com> (raw)
In-Reply-To: <CA+55aFxa_1pCMt-GQmBZUzRbc8_UY9sacmEaCqkDM1_=sq8y_A@mail.gmail.com>
* Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Tue, Oct 3, 2017 at 7:06 AM, Fengguang Wu <fengguang.wu@intel.com> wrote:
> >
> > This patch triggers a NULL-dereference bug at update_stack_state().
> > Although its parent commit also has a NULL-dereference bug, however
> > the call stack looks rather different. Both dmesg files are attached.
> >
> > It also triggers this warning, which is being discussed in another
> > thread, so CC Josh. The full dmesg attached, too.
> >
> > Please press Enter to activate this console.
> > [ 138.605622] WARNING: kernel stack regs at be299c9a in procd:340 has bad 'bp' value 000001be
> > [ 138.605627] unwind stack type:0 next_sp: (null) mask:0x2 graph_idx:0
> > [ 138.605631] be299c9a: 299ceb00 (0x299ceb00)
> > [ 138.605633] be299c9e: 2281f1be (0x2281f1be)
> > [ 138.605634] be299ca2: 299cebb6 (0x299cebb6)
> >
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> >
> > commit b09be676e0ff25bd6d2e7637e26d349f9109ad75
> > locking/lockdep: Implement the 'crossrelease' feature
>
> Can we consider just reverting the crossrelease thing?
Yes, I'll do that tomorrow. I was always a bit unhappy about cross-release,
because it breaks the 'owner task owns the lock' model. Plus I don't think
we found that many real bugs with it - in a 20+ years old, 15+ MLOC code
base that never run with such a debugging facility enabled.
Thanks,
Ingo
next prev parent reply other threads:[~2017-10-03 17:18 UTC|newest]
Thread overview: 102+ 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 14:06 ` Fengguang Wu
2017-10-03 14:31 ` Josh Poimboeuf
2017-10-03 14:31 ` Josh Poimboeuf
2017-10-03 14:41 ` Josh Poimboeuf
2017-10-03 14:41 ` Josh Poimboeuf
2017-10-03 15:05 ` Josh Poimboeuf
2017-10-03 15:05 ` Josh Poimboeuf
2017-10-03 16:28 ` Josh Poimboeuf
2017-10-03 16:28 ` Josh Poimboeuf
2017-10-03 17:34 ` Josh Poimboeuf
2017-10-03 17:34 ` Josh Poimboeuf
2017-10-03 21:44 ` Tetsuo Handa
2017-10-03 21:44 ` Tetsuo Handa
2017-10-04 21:06 ` Josh Poimboeuf
2017-10-04 21:06 ` Josh Poimboeuf
2017-10-04 21:30 ` Linus Torvalds
2017-10-04 21:30 ` Linus Torvalds
2017-10-04 22:15 ` Josh Poimboeuf
2017-10-04 22:15 ` Josh Poimboeuf
2017-10-04 22:40 ` Josh Poimboeuf
2017-10-04 22:40 ` Josh Poimboeuf
2017-10-05 11:02 ` Tetsuo Handa
2017-10-05 11:02 ` Tetsuo Handa
2017-10-05 13:57 ` Josh Poimboeuf
2017-10-05 13:57 ` Josh Poimboeuf
2017-10-04 8:34 ` Peter Zijlstra
2017-10-04 8:34 ` Peter Zijlstra
2017-10-10 5:57 ` Byungchul Park
2017-10-10 5:57 ` Byungchul Park
2017-10-03 16:54 ` Linus Torvalds
2017-10-03 16:54 ` Linus Torvalds
2017-10-03 16:57 ` Linus Torvalds
2017-10-03 16:57 ` Linus Torvalds
2017-10-10 5:48 ` Byungchul Park
2017-10-10 5:48 ` Byungchul Park
2017-10-10 16:22 ` Linus Torvalds
2017-10-10 16:22 ` Linus Torvalds
2017-10-10 16:56 ` Linus Torvalds
2017-10-10 16:56 ` Linus Torvalds
2017-10-10 18:14 ` Peter Zijlstra
2017-10-10 18:14 ` Peter Zijlstra
2017-10-10 18:38 ` Linus Torvalds
2017-10-10 18:38 ` Linus Torvalds
2017-10-11 1:14 ` Byungchul Park
2017-10-11 1:14 ` Byungchul Park
2017-10-11 2:36 ` Byungchul Park
2017-10-11 2:36 ` Byungchul Park
2017-10-11 0:56 ` Byungchul Park
2017-10-11 0:56 ` Byungchul Park
2017-10-11 1:02 ` Byungchul Park
2017-10-11 1:02 ` Byungchul Park
2017-10-12 1:15 ` Byungchul Park
2017-10-12 1:15 ` Byungchul Park
2017-10-03 17:18 ` Ingo Molnar [this message]
2017-10-03 17:18 ` Ingo Molnar
2017-10-04 9:20 ` Peter Zijlstra
2017-10-04 9:20 ` Peter Zijlstra
2017-10-04 10:31 ` Ingo Molnar
2017-10-04 10:31 ` Ingo Molnar
2017-10-04 14:15 ` Josh Poimboeuf
2017-10-04 14:15 ` Josh Poimboeuf
2017-10-10 5:30 ` Byungchul Park
2017-10-10 5:30 ` Byungchul Park
2017-10-05 13:01 ` Josh Poimboeuf
2017-10-05 13:01 ` Josh Poimboeuf
2017-10-05 14:54 ` Josh Poimboeuf
2017-10-05 14:54 ` Josh Poimboeuf
2017-10-09 10:50 ` Peter Zijlstra
2017-10-09 10:50 ` Peter Zijlstra
2017-10-09 12:21 ` Fengguang Wu
2017-10-09 12:21 ` Fengguang Wu
2017-10-09 12:54 ` Peter Zijlstra
2017-10-09 12:54 ` Peter Zijlstra
2017-10-09 12:59 ` Fengguang Wu
2017-10-09 12:59 ` Fengguang Wu
2017-10-09 13:03 ` Josh Poimboeuf
2017-10-09 13:03 ` Josh Poimboeuf
2017-10-09 12:55 ` Fengguang Wu
2017-10-09 12:55 ` Fengguang Wu
2017-10-09 13:26 ` Josh Poimboeuf
2017-10-09 13:26 ` Josh Poimboeuf
2017-10-09 14:17 ` Fengguang Wu
2017-10-09 14:17 ` Fengguang Wu
2017-10-09 15:28 ` Peter Zijlstra
2017-10-09 15:28 ` Peter Zijlstra
2017-10-09 15:41 ` Fengguang Wu
2017-10-09 15:41 ` Fengguang Wu
2017-10-09 15:44 ` Peter Zijlstra
2017-10-09 15:44 ` Peter Zijlstra
2017-10-09 15:47 ` Fengguang Wu
2017-10-09 15:47 ` Fengguang Wu
2017-10-10 5:08 ` Byungchul Park
2017-10-10 5:08 ` Byungchul Park
2017-10-12 8:47 ` Peter Zijlstra
2017-10-12 8:47 ` Peter Zijlstra
2017-10-12 9:21 ` Fengguang Wu
2017-10-12 9:21 ` Fengguang Wu
2017-10-12 9:28 ` Fengguang Wu
2017-10-12 9:28 ` Fengguang Wu
2017-10-12 11:45 ` Peter Zijlstra
2017-10-12 11:45 ` Peter Zijlstra
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