Hi,

in the patch attached I improved the memory usage for my data structures by 
using a kmem_cache. Also I do not use a single radix-tree for the pointers to 
the list anymore but every mapping gets its own... So I should be able to 
prefetch not only from the swap space but from other disk-places, too.

But exactly this does not work and I need some help with this...
If I do add pages from the swaper_space mapping to the prefetch list 
everything works perfectly. But as soon as I add all pages with a mapping to 
the list I get the Oops attached... :-(

It happens in the radix_tree_delete call from the swap_prefetch work handler. 
So I think I access an invalid (perhaps not initialized?) radix tree... But 
why I wonder is that this entry was properly inserted to the tree, because 
else it would never had been inserted to the list!

So I am only very confused..!

Thanks for your help!

   Thomas Schlichter

On April 12, Andrew Morton wrote:
> Thomas Schlichter <schlicht@uni-mannheim.de> wrote:
> > How can I get the file pointer for a buffered page with the information
> > available in the kswapd (minly the page struct)??
>
> You can't, really.  There can be any number of file*'s pointing at an
> inode.

OK, I understand...

> The pagefault handler will find it by find_vma(faulting_address)->vm_file.
> Other codepaths use syscalls, and the user passed the file* in.
>
> You can call page_cache_readahead() with a NULL file*.  That'll mostly work
> except for the odd filesytem like NFS which will oops.  But it's good
> enough for testing and development.

That's the way I try it now... ;-)

> Or you could cook up a local file struct along the lines of
> fs/nfsd/vfs.c:nfsd_read(), but I would not like to lead a young person
> that way ;)

Thx... ;-)