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* Re: mmotm 2010-02-10 - BUG at fs/dcache.c:677!
       [not found] ` <8576.1265942657@localhost>
@ 2010-02-12  3:14   ` Andrew Morton
  2010-02-12  4:51     ` Jun'ichi Nomura
  0 siblings, 1 reply; 5+ messages in thread
From: Andrew Morton @ 2010-02-12  3:14 UTC (permalink / raw)
  To: Valdis.Kletnieks
  Cc: linux-kernel, linux-fsdevel, Al Viro, linux-s390, linux-next,
	Heiko Carstens

On Thu, 11 Feb 2010 21:44:17 -0500 Valdis.Kletnieks@vt.edu wrote:

> On Wed, 10 Feb 2010 16:17:41 PST, akpm@linux-foundation.org said:
> > The mm-of-the-moment snapshot 2010-02-10-16-17 has been uploaded to
> > 
> >    http://userweb.kernel.org/~akpm/mmotm/
> 
> Hit this at shutdown. ext4 filesystems.  Brought it up to single-user
> mode, then 'shutdown -h now'.
> 
> [   58.311786] ------------[ cut here ]------------
> [   58.312261] kernel BUG at fs/dcache.c:677!
> [   58.312261] invalid opcode: 0000 [#1] PREEMPT SMP 
> [   58.312261] last sysfs file: /sys/devices/virtual/block/dm-10/dm/name
> [   58.312261] CPU 1 
> [   58.312261] Pid: 3007, comm: umount Not tainted 2.6.33-rc7-mmotm0210 #1 0X564R/Latitude E6500                  
> [   58.312261] RIP: 0010:[<ffffffff810e7ce8>]  [<ffffffff810e7ce8>] shrink_dcache_for_umount_subtree+0x19b/0x27e
> [   58.312261] RSP: 0018:ffff88011bafde08  EFLAGS: 00010292
> [   58.312261] RAX: 000000000000006b RBX: ffff88011be58160 RCX: ffffffff81a2b070
> [   58.312261] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff81aa3fe8
> [   58.312261] RBP: ffff88011bafde38 R08: 0000000000000002 R09: 0000000000000000
> [   58.312261] R10: 0000000000000005 R11: 0000000000000000 R12: ffff88011be58160
> [   58.312261] R13: 0000000000000088 R14: ffff88011be824c0 R15: ffff88011bafdf18
> [   58.312261] FS:  00007f1348f7e740(0000) GS:ffff880100300000(0000) knlGS:0000000000000000
> [   58.312261] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   58.312261] CR2: 00007f1348642c40 CR3: 000000011ce86000 CR4: 00000000000406e0
> [   58.312261] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [   58.312261] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [   58.312261] Process umount (pid: 3007, threadinfo ffff88011bafc000, task ffff88011d88c640)
> [   58.312261] Stack:
> [   58.312261]  ffff88010f7e9418 ffff88010f7e9248 ffff88010f7e9000 ffffffff816270b0
> [   58.312261] <0> ffff88010f7e9000 ffffffff81b08d28 ffff88011bafde58 ffffffff810e7e02
> [   58.312261] <0> ffffffff81a37ed0 ffff88010f7e9000 ffff88011bafde78 ffffffff810d8785
> [   58.312261] Call Trace:
> [   58.312261]  [<ffffffff810e7e02>] shrink_dcache_for_umount+0x37/0x47
> [   58.312261]  [<ffffffff810d8785>] generic_shutdown_super+0x1a/0xc9
> [   58.312261]  [<ffffffff810d8856>] kill_block_super+0x22/0x3a
> [   58.312261]  [<ffffffff810d8ff5>] deactivate_super+0x68/0x7f
> [   58.312261]  [<ffffffff810eda94>] mntput_no_expire+0x10d/0x150
> [   58.312261]  [<ffffffff810ee04c>] sys_umount+0x2be/0x2ed
> [   58.312261]  [<ffffffff81062361>] ? trace_hardirqs_on_caller+0x16/0x13c
> [   58.312261]  [<ffffffff8100252b>] system_call_fastpath+0x16/0x1b
> [   58.312261] Code: 0a 48 8b 4b 68 31 d2 48 85 f6 74 04 48 8b 56 40 48 05 18 04 00 00 48 89 de 48 89 04 24 48 c7 c7 48 b0 80 81 31 c0 e8 3e fa 47 00 <0f> 0b eb fe 4c 8b 63 58 4c 39 e3 75 05 45 31 e4 eb 05 f0 41 ff 
> [   58.312261] RIP  [<ffffffff810e7ce8>] shrink_dcache_for_umount_subtree+0x19b/0x27e

Yeah, Sachin reported that against linux-next too (I think - need to
check the exact line numbers):
http://permalink.gmane.org/gmane.linux.file-systems/38148

It seems to have been met with shrugs thus far.

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: mmotm 2010-02-10 - BUG at fs/dcache.c:677!
  2010-02-12  3:14   ` mmotm 2010-02-10 - BUG at fs/dcache.c:677! Andrew Morton
@ 2010-02-12  4:51     ` Jun'ichi Nomura
  2010-02-12  5:01       ` Al Viro
  2010-02-12  5:30       ` Stephen Rothwell
  0 siblings, 2 replies; 5+ messages in thread
From: Jun'ichi Nomura @ 2010-02-12  4:51 UTC (permalink / raw)
  To: Andrew Morton, Al Viro
  Cc: Valdis.Kletnieks, linux-kernel, linux-fsdevel, linux-s390,
	linux-next, Heiko Carstens

(02/12/10 12:14), Andrew Morton wrote:
> On Thu, 11 Feb 2010 21:44:17 -0500 Valdis.Kletnieks@vt.edu wrote:
> 
>> On Wed, 10 Feb 2010 16:17:41 PST, akpm@linux-foundation.org said:
>>> The mm-of-the-moment snapshot 2010-02-10-16-17 has been uploaded to
>>>
>>>    http://userweb.kernel.org/~akpm/mmotm/
>>
>> Hit this at shutdown. ext4 filesystems.  Brought it up to single-user
>> mode, then 'shutdown -h now'.
>>
>> [   58.311786] ------------[ cut here ]------------
>> [   58.312261] kernel BUG at fs/dcache.c:677!
...

> Yeah, Sachin reported that against linux-next too (I think - need to
> check the exact line numbers):
> http://permalink.gmane.org/gmane.linux.file-systems/38148
> 
> It seems to have been met with shrugs thus far.

According to the Sachin's report:
> While running hackbench against today's next-20100208 (9056d31..)
> on a s390 box, came across following BUG.
...
> Did not observe this with next-20100205. Also there doesn't seem to be
> any patches applied to this code after the last release. So not
> sure what could have caused this. Corresponding code is :

So the bug seems introduced between next-20100205 and next-20100208.

Isn't this change missing the equivalent of "dput(old)"?

In patch-v2.6.33-rc7-next-20100208:
> diff --git a/fs/namei.c b/fs/namei.c
> index 94a5e60..a056dad 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -689,33 +689,17 @@ static __always_inline void follow_dotdot(struct nameidata *nd)
...
> -               spin_lock(&dcache_lock);
>                 if (nd->path.dentry != nd->path.mnt->mnt_root) {
> -                       nd->path.dentry = dget(nd->path.dentry->d_parent);
> -                       spin_unlock(&dcache_lock);
> -                       dput(old);
> +                       /* rare case of legitimate dget_parent()... */
> +                       nd->path.dentry = dget_parent(nd->path.dentry);
>                         break;
>                 }

-- 
Jun'ichi Nomura, NEC Corporation

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: mmotm 2010-02-10 - BUG at fs/dcache.c:677!
  2010-02-12  4:51     ` Jun'ichi Nomura
@ 2010-02-12  5:01       ` Al Viro
  2010-02-12  5:07         ` Al Viro
  2010-02-12  5:30       ` Stephen Rothwell
  1 sibling, 1 reply; 5+ messages in thread
From: Al Viro @ 2010-02-12  5:01 UTC (permalink / raw)
  To: Jun'ichi Nomura
  Cc: Andrew Morton, Valdis.Kletnieks, linux-kernel, linux-fsdevel,
	linux-s390, linux-next, Heiko Carstens

On Fri, Feb 12, 2010 at 01:51:12PM +0900, Jun'ichi Nomura wrote:
> (02/12/10 12:14), Andrew Morton wrote:
> > On Thu, 11 Feb 2010 21:44:17 -0500 Valdis.Kletnieks@vt.edu wrote:
> > 
> >> On Wed, 10 Feb 2010 16:17:41 PST, akpm@linux-foundation.org said:
> >>> The mm-of-the-moment snapshot 2010-02-10-16-17 has been uploaded to
> >>>
> >>>    http://userweb.kernel.org/~akpm/mmotm/
> >>
> >> Hit this at shutdown. ext4 filesystems.  Brought it up to single-user
> >> mode, then 'shutdown -h now'.
> >>
> >> [   58.311786] ------------[ cut here ]------------
> >> [   58.312261] kernel BUG at fs/dcache.c:677!
> ...
> 
> > Yeah, Sachin reported that against linux-next too (I think - need to
> > check the exact line numbers):
> > http://permalink.gmane.org/gmane.linux.file-systems/38148
> > 
> > It seems to have been met with shrugs thus far.
> 
> According to the Sachin's report:
> > While running hackbench against today's next-20100208 (9056d31..)
> > on a s390 box, came across following BUG.
> ...
> > Did not observe this with next-20100205. Also there doesn't seem to be
> > any patches applied to this code after the last release. So not
> > sure what could have caused this. Corresponding code is :
> 
> So the bug seems introduced between next-20100205 and next-20100208.
> 
> Isn't this change missing the equivalent of "dput(old)"?

Argh...  Nice catch, and yes, it is.

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: mmotm 2010-02-10 - BUG at fs/dcache.c:677!
  2010-02-12  5:01       ` Al Viro
@ 2010-02-12  5:07         ` Al Viro
  0 siblings, 0 replies; 5+ messages in thread
From: Al Viro @ 2010-02-12  5:07 UTC (permalink / raw)
  To: Jun'ichi Nomura
  Cc: Andrew Morton, Valdis.Kletnieks, linux-kernel, linux-fsdevel,
	linux-s390, linux-next, Heiko Carstens

On Fri, Feb 12, 2010 at 05:01:04AM +0000, Al Viro wrote:

> > So the bug seems introduced between next-20100205 and next-20100208.
> > 
> > Isn't this change missing the equivalent of "dput(old)"?
> 
> Argh...  Nice catch, and yes, it is.

Fixed, pushed to hera, should propagate to git.kernel.org shortly.

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: mmotm 2010-02-10 - BUG at fs/dcache.c:677!
  2010-02-12  4:51     ` Jun'ichi Nomura
  2010-02-12  5:01       ` Al Viro
@ 2010-02-12  5:30       ` Stephen Rothwell
  1 sibling, 0 replies; 5+ messages in thread
From: Stephen Rothwell @ 2010-02-12  5:30 UTC (permalink / raw)
  To: Jun'ichi Nomura
  Cc: Andrew Morton, Al Viro, Valdis.Kletnieks, linux-kernel,
	linux-fsdevel, linux-s390, linux-next, Heiko Carstens

[-- Attachment #1: Type: text/plain, Size: 1231 bytes --]

Hi all,

On Fri, 12 Feb 2010 13:51:12 +0900 "Jun'ichi Nomura" <j-nomura@ce.jp.nec.com> wrote:
>
> So the bug seems introduced between next-20100205 and next-20100208.
> 
> Isn't this change missing the equivalent of "dput(old)"?
> 
> In patch-v2.6.33-rc7-next-20100208:
> > diff --git a/fs/namei.c b/fs/namei.c
> > index 94a5e60..a056dad 100644
> > --- a/fs/namei.c
> > +++ b/fs/namei.c
> > @@ -689,33 +689,17 @@ static __always_inline void follow_dotdot(struct nameidata *nd)
> ...
> > -               spin_lock(&dcache_lock);
> >                 if (nd->path.dentry != nd->path.mnt->mnt_root) {
> > -                       nd->path.dentry = dget(nd->path.dentry->d_parent);
> > -                       spin_unlock(&dcache_lock);
> > -                       dput(old);
> > +                       /* rare case of legitimate dget_parent()... */
> > +                       nd->path.dentry = dget_parent(nd->path.dentry);
> >                         break;
> >                 }

That is part of commit 12578f932a8ad5f01bbf957d9c941760ef0dc575 ("Clean
follow_dotdot() up a bit") from the vfs tree.
-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/

[-- Attachment #2: Type: application/pgp-signature, Size: 198 bytes --]

^ permalink raw reply	[flat|nested] 5+ messages in thread

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2010-02-12  3:14   ` mmotm 2010-02-10 - BUG at fs/dcache.c:677! Andrew Morton
2010-02-12  4:51     ` Jun'ichi Nomura
2010-02-12  5:01       ` Al Viro
2010-02-12  5:07         ` Al Viro
2010-02-12  5:30       ` Stephen Rothwell

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