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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 14:08:42 +0900	[thread overview]
Message-ID: <20171010050842.GB3323@X58A-UD3R> (raw)
In-Reply-To: <CA+55aFxa_1pCMt-GQmBZUzRbc8_UY9sacmEaCqkDM1_=sq8y_A@mail.gmail.com>

On Tue, Oct 03, 2017 at 09:54:31AM -0700, Linus Torvalds 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

Hello,

I'm sorry for late. It was the biggest traditional holiday in Korea
until yesterday.

> Can we consider just reverting the crossrelease thing?
> 
> The apparent stack corruption really worries me, and what worries me
> most is that commit wasn't even supposed to change anything as far as
> I can tell - it only adds infrastructure, no actual users that *set*
> the cross-lock thing.

All users of wait_for_completion() and lock_page() are implicitly actual
users with CONFIG_LOCKDEP_CROSSRELEASE enabled, which sets the crosslock
thing internally on its initialization.

WARNING: multiple messages have this Message-ID (diff)
From: Byungchul Park <byungchul.park@lge.com>
To: lkp@lists.01.org
Subject: Re: [lockdep] b09be676e0 BUG: unable to handle kernel NULL pointer dereference at 000001f2
Date: Tue, 10 Oct 2017 14:08:42 +0900	[thread overview]
Message-ID: <20171010050842.GB3323@X58A-UD3R> (raw)
In-Reply-To: <CA+55aFxa_1pCMt-GQmBZUzRbc8_UY9sacmEaCqkDM1_=sq8y_A@mail.gmail.com>

[-- Attachment #1: Type: text/plain, Size: 1744 bytes --]

On Tue, Oct 03, 2017 at 09:54:31AM -0700, Linus Torvalds 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

Hello,

I'm sorry for late. It was the biggest traditional holiday in Korea
until yesterday.

> Can we consider just reverting the crossrelease thing?
> 
> The apparent stack corruption really worries me, and what worries me
> most is that commit wasn't even supposed to change anything as far as
> I can tell - it only adds infrastructure, no actual users that *set*
> the cross-lock thing.

All users of wait_for_completion() and lock_page() are implicitly actual
users with CONFIG_LOCKDEP_CROSSRELEASE enabled, which sets the crosslock
thing internally on its initialization.


  parent reply	other threads:[~2017-10-10  5:08 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
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 [this message]
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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