Re: [PATCH *] VM patch for 2.4.0-test8

["Juan J. Quintela" <quintela@fi.udc.es>]

>>>>> "david" == David S Miller <davem@redhat.com> writes:

david> In page_launder() about halfway down there is this sequence of tests
david> on LRU pages:

david> if (!clearedbuf) {
david>  ...
david> } else if (!page->mapping) {
david>  ...
david> } else if (page_count(page) > 1) {
david> } else /* page->mapping && page_count(page) == 1 */ {
david>  ...
david> }

david> Above this sequence we've done a page_cache_get.  For the final case
david> in the tests above (page->mapping != NULL && page_count(page) == 1)
david> have you checked if this ever happens or is even possible?

david> If the page is a page cache page (ie. page->mapping != NULL) it
david> should hold a reference.  Adding in our reference, the count should
david> always thus be > 1.

david> What did I miss?

I think nothing, I suppose that riel means > 2 and == 2, if we arrive
there when a page count of 1 we are in problems as you have told.

/me doing greping ...... <some time later>

I can only see one place where we add a page to the page cache and we
don't increase its page count, and it is in grow_buffers().  Could
somebody explain me _why_ we don't need to do a page_cache_get(page)
in that function? 

Later, Juan.



-- 
In theory, practice and theory are the same, but in practice they 
are different -- Larry McVoy
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