[OOPS] sysfs_hash_and_remove (was Re: What protection ....)

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

On Wed, Nov 23, 2005 at 09:18:45AM +0100, Ingo Molnar wrote:
> 
[..]
> on a related note - i've been carrying the patch below in -rt for 2 
> months (i.e. Steven's kernel has it too), as a workaround against the 
> crash described below.
> 
[..]

> i'm occasionally getting the crash below on a PREEMPT_RT kernel. Might 
> be a PREEMPT_RT bug, or might be some sysfs race only visible under 
> PREEMPT_RT. Any ideas? The crash is at:
> 
> (gdb) list *0xc01a2095
> 0xc01a2095 is in sysfs_hash_and_remove (fs/sysfs/inode.c:229).
> 224     }
> 225
> 226     void sysfs_hash_and_remove(struct dentry * dir, const char * name)
> 227     {
> 228             struct sysfs_dirent * sd;
> 229             struct sysfs_dirent * parent_sd = dir->d_fsdata;
> 230
> 231             if (dir->d_inode == NULL)
> 232                     /* no inode means this hasn't been made visible yet */
> 233                     return;
> (gdb)
> 
Looks like here it is crashing due to bogus dentry pointer in the kobject 
kobj->dentry. Could be some stale pointer? 

Just got the mbox.. will go thru it more closely..

-- 
Maneesh Soni
Linux Technology Center, 
IBM India Software Labs,
Bangalore, India
email: maneesh@in.ibm.com
Phone: 91-80-25044990