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

[Maneesh Soni <maneesh@in.ibm.com>]

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 écrit :
> >  > 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;
_




-- 
Maneesh Soni
Linux Technology Center, 
IBM India Software Labs,
Bangalore, India
email: maneesh@in.ibm.com
Phone: 91-80-51776416
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