Re: [PATCH 0/7] Kill PF_MEMALLOC abuse

[Christoph Hellwig <hch@infradead.org>]

On Tue, Nov 17, 2009 at 09:24:24PM +0900, KOSAKI Motohiro wrote:
> > On Tue, Nov 17, 2009 at 07:24:42PM +0900, KOSAKI Motohiro wrote:
> > > if xfsbufd doesn't only write out dirty data but also drop page,
> > > I agree you. 
> > 
> > It then drops the reference to the buffer which drops references to the
> > pages, which often are the last references, yes.
> 
> I though it is not typical case. Am I wrong?
> if so, I'm sorry. I'm not XFS expert.

I think in the typical case it's the last reference.  The are two
reasons why it might not be:

 - we're on a filesystem with block size < page size in which case two
   buffers can share a page and we'd need to write out and release both
   buffers to free the page
 - someone else might have a reference on the buffer.  Offhand I can't
   remember a place where we do this for delayed write buffers (which
   is what xfsbufd writes out) as it would be a bit against the purpose
   of those delayed write buffers.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>