Re: [PATCH 1/3] [FIX] hugetlb: Fix broken fs quota management

[Adam Litke <agl@us.ibm.com>]

On Wed, 2007-10-24 at 12:21 -0700, Ken Chen wrote:
> On 10/24/07, Adam Litke <agl@us.ibm.com> wrote:
> > On Wed, 2007-10-24 at 11:43 -0700, Dave Hansen wrote:
> > > This particular nugget is for MAP_PRIVATE pages only, right?  The shared
> > > ones should have another ref out on them for the 'mapping' too, so won't
> > > get released at unmap, right?
> >
> > Yep that's right.  Shared pages are released by truncate_hugepages()
> > when the ref for the mapping is dropped.
> 
> I think as a follow up patch, we should debit the quota in
> free_huge_page(), so you don't have to open code it like this and also
> consolidate calls to hugetlb_put_quota() in one place.  It's cleaner
> that way.

At free_huge_page() time, you can't associate the page with a struct
address_space so it becomes hard to credit the proper filesystem.  When
freeing the page, page->mapping is no longer valid (even for shared
pages). 

-- 
Adam Litke - (agl at us.ibm.com)
IBM Linux Technology Center

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