Re: kernel BUG at include/linux/dcache.h:271!

[Jens Axboe <axboe@suse.de>]

On Thu, May 22 2003, Andrew Morton wrote:
> Maneesh Soni <maneesh@in.ibm.com> wrote:
> >
> > The problem is that we have multiple ramdisks but all have
> > common request queue and common elevator. In terms of sysfs we 
> > have multiple kobjects for multiple ramdisks, but one single kobject for the 
> > ramdisks' common elevator. 
> > 
> > While initializing, different kobjects are allocated for the ramdisks but,
> > the common elevator uses the same kobject. In other words, every init
> > of a ramdisk, the common elevator.kobj->parent will be different and it will
> > allocate a new dentry, overwrite the elevator.kobj->dentry
> > and loose the earlier allocated dentries. (see: elv_register_queue())
> > 
> > While exiting, it ends up in removing the same dentry (allocated at the last)
> > again and BUGs in dget on dentry with zero ref count.
> > 
> > Not sure where it should be fixed 
> > ramdisk 
> >  - should have separate queues on for each ramdisk
> > 
> > elevator 
> >  - should not re-register already registered queue in elv_register_queue
> > 
> > sysfs 
> >  - should handle kobject with multiple parent kobjects 
> 
> I can't think of anywhere else where we are likely to want to support
> multiple devices from a single queue in this manner, so perhaps the best
> solution is to remove the exceptional case: allocate a separate queue for
> each ramdisk instance.
> 
> Jens, do you agree?

Completely and utterly agree :)

-- 
Jens Axboe