Re: [patch] hugetlb strict commit accounting - v3

['David Gibson' <david@gibson.dropbear.id.au>]

On Thu, Mar 09, 2006 at 08:46:53PM -0800, Andrew Morton wrote:
> "'David Gibson'" <david@gibson.dropbear.id.au> wrote:
> >
> > On Thu, Mar 09, 2006 at 07:14:58PM -0800, Chen, Kenneth W wrote:
> > > hugetlb strict commit accounting for shared mapping - v3
> > > 
> > > The a region reservation list is implementation as a linked list
> > > hanging off address_space i_data->private_list.  It turns out that
> > > clear_inode() was also looking at inode->i_data->private_list and
> > > if not empty, it think inode has dirty buffers and start clearing.
> > > Except it won't go very far before oops-ing.  That could happen if
> > > a reservation is made but no actual faulting. hugetlbfs_delete_inode
> > > and hugetlbfs_forget_inode doesn't call truncate_hugepages if there
> > > are no actual page in the page cache, leading to clear_inode to do
> > > bad thing.  Change that to always call truncate_hugepages even if
> > > there are no pages in page cache and to let the unreserve code to
> > > clear out the reservation linked list.
> > 
> > Hrm.. overloading the private_list in this manner sounds fragile.
> > Maybe we should move the list into the hugetlbfs specific inode data.
> 
> private_list and private_lock are available for use by the subsystem which
> owns this mapping's address_space_operations.  ie: hugetlbfs.

If that's so, why is clear_inode messing with it?

> It's been this way for several years but afaik this is the first time
> that's actually been taken advantage of.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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