Re: 2.6.16-rc6-mm1: BUG at fs/sysfs/inode.c:180

[Greg KH <greg@kroah.com>]

On Mon, Mar 13, 2006 at 06:04:52PM +0100, Laurent Riffard wrote:
> 
> Le 13.03.2006 15:00, Maneesh Soni a ?crit :
> > On Sun, Mar 12, 2006 at 03:01:58PM -0800, Andrew Morton wrote:
> >>Laurent Riffard <laurent.riffard@free.fr> wrote:
> >>>Le 12.03.2006 12:10, Andrew Morton a ?crit :
> >>> > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.16-rc6/2.6.16-rc6-mm1/
> >>>
> >>> Hello,
> >>>
> >>> This kernel hangs on boot while trying to activate logical 
> >>> volumes from initrd: 
> >>>
> >>> ------------[ cut here ]------------
> >>> kernel BUG at fs/sysfs/inode.c:180!
> >>> invalid opcode: 0000 [#1]
> >>> last sysfs file: /block/ram0/dev
> >>> Modules linked in: dm_mirror dm_mod
> >>> CPU:    0
> >>> EIP:    0060:[<c0172e71>]    Not tainted VLI
> >>> EFLAGS: 00010246   (2.6.16-rc6-mm1 #123) 
> >>> EIP is at sysfs_get_name+0xd/0x46
> >>> eax: c15a49c8   ebx: dfe2b988   ecx: dff254d8   edx: c15a49cc
> >>> esi: dfe87b05   edi: dfe2b988   ebp: dfe67d28   esp: dfe67d28
> >>> ds: 007b   es: 007b   ss: 0068
> >>> Process vgchange (pid: 242, threadinfo=dfe67000 task=dfe175d0)
> >>> Stack: <0>dfe67d44 c01738c3 dffdc4b4 c15a49c8 dfe2b988 ffffffef dfe2b98d dfe67d60 
> >>>        c0173dcd dff2a804 dfe2b984 dfe2b984 00000001 fffffffe dfe67d74 c0173f3b 
> >>>        dfe67d6c c15a84d4 dfe2b984 dfe67d90 c01a33fd c03242d0 00000004 dfe2b8f8 
> >>> Call Trace:
> >>>  [<c0103a31>] show_stack_log_lvl+0x8b/0x95
> >>>  [<c0103b69>] show_registers+0x12e/0x194
> >>>  [<c0103e62>] die+0x14e/0x1db
> >>>  [<c01040ba>] do_trap+0x7c/0x96
> >>>  [<c0104319>] do_invalid_op+0x89/0x93
> >>>  [<c01034db>] error_code+0x4f/0x54
> >>>  [<c01738c3>] sysfs_dirent_exist+0x1c/0x65
> >>>  [<c0173dcd>] create_dir+0x55/0x17d
> >>>  [<c0173f3b>] sysfs_create_dir+0x46/0x61
> >>>  [<c01a33fd>] kobject_add+0xa4/0x14c
> >>>  [<c017267e>] register_disk+0x4b/0xe9
> >>>  [<c019c28c>] add_disk+0x2e/0x3d
> >>>  [<e08198a5>] create_aux+0x27e/0x2d7 [dm_mod]
> >>>  [<e081991d>] dm_create+0xe/0x10 [dm_mod]
> >>>  [<e081c317>] dev_create+0x4a/0x239 [dm_mod]
> >>>  [<e081c18c>] ctl_ioctl+0x203/0x238 [dm_mod]
> >>>  [<c0156648>] do_ioctl+0x3c/0x4f
> >>>  [<c0156851>] vfs_ioctl+0x1f6/0x20d
> >>>  [<c0156892>] sys_ioctl+0x2a/0x44
> >>>  [<c01029bb>] sysenter_past_esp+0x54/0x75
> >>> Code: 0b 30 01 72 85 28 c0 ff 06 31 db eb 07 89 f8 e8 d1 8d fe ff 83 c4 10 89 d8 5b 5e 5f c9 c3 55 85 c0 89 e5 74 06 83 78 14 00 75 08 <0f> 0b b4 00 73 d3 28 c0 8b 50 18 83 fa 08 74 22 7f 0a 83 fa 02 
> >>
> >>Thanks.
> >>
> >>Greg, can you please interpret this?  What does this BUG:
> >>
> >>const unsigned char * sysfs_get_name(struct sysfs_dirent *sd)
> >>{
> >>	struct attribute * attr;
> >>	struct bin_attribute * bin_attr;
> >>	struct relay_attribute * rel_attr;
> >>	struct sysfs_symlink  * sl;
> >>
> >>	if (!sd || !sd->s_element)
> >>		BUG();
> >>
> >>tell us?
> >>
> > 
> > 
> > I think here we have sd->s_element as NULL. This is probably due to
> > my mistake in 
> > 
> > gregkh-driver-sysfs-fix-problem-with-duplicate-sysfs-directories-and-files.patch
> > 
> > NULL s_element which is used as cursor element is added to the s_children 
> > list in sysfs_dir_open() and is removed in sysfs_dir_close(). So if in
> > between s_children is parsed, one can see sysfs_dirent with NULL s_element.
> > 
> > Please try the following patch on top of -mm1
> > 
> > 
> > Thanks
> > Maneesh
> > 
> > 
> > 
> > 
> > o sysfs_dirent_exist() should ignore sysfs_dirent with NULL s_element
> >   as such element could have been added internally as cursor due to
> >   ->open() on parent directory.
> > 
> > Signed-off-by: Maneesh Soni <maneesh@in.ibm.com>
> > ---
> > 
> >  linux-2.6.16-rc6-mm1-maneesh/fs/sysfs/dir.c |   12 +++++++-----
> >  1 files changed, 7 insertions(+), 5 deletions(-)
> > 
> > diff -puN fs/sysfs/dir.c~fix-sysfs-check-existing-sysfs_dirent fs/sysfs/dir.c
> > --- linux-2.6.16-rc6-mm1/fs/sysfs/dir.c~fix-sysfs-check-existing-sysfs_dirent	2006-03-13 14:48:34.000000000 +0530
> > +++ linux-2.6.16-rc6-mm1-maneesh/fs/sysfs/dir.c	2006-03-13 15:01:32.934811856 +0530
> > @@ -63,11 +63,13 @@ int sysfs_dirent_exist(struct sysfs_dire
> >  	struct sysfs_dirent * sd;
> >  
> >  	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
> > -		const unsigned char * existing = sysfs_get_name(sd);
> > -		if (strcmp(existing, new))
> > -			continue;
> > -		else
> > -			return -EEXIST;
> > +		if (sd->s_element) {
> > +			const unsigned char * existing = sysfs_get_name(sd);
> > +			if (strcmp(existing, new))
> > +				continue;
> > +			else
> > +				return -EEXIST;
> > +		}
> >  	}
> >  
> >  	return 0;
> > _
> > 
> 
> Ok, with this one, it works fine. 

Thanks Maneesh for the quick fix, want me to merge this with your
previous patch?

thanks,

greg k-h