On Fri, Feb 10, 2012 at 12:01:05PM -0500, Rik van Riel wrote:

On 02/10/2012 11:37 AM, Mel Gorman wrote:

quoted

On Thu, Jan 19, 2012 at 12:24:48PM -0800, Andrew Morton wrote:

quoted

quoted

I think it is was always wrong that we only strip buffer_heads when
moving pages to the inactive list.  What happens if those 600MB of
buffer_heads are all attached to inactive pages?

I wondered the same thing myself. With some use-once logic, there is
no guarantee that they even get promoted to the active list in the
first place. It's "always" been like this but we've changed how pages gets
promoted quite a bit and this use case could have been easily missed.

It may be possible to also strip the buffer heads from
pages when they are moved to the active list, in
activate_page().

It'd be possible but is that really the right thing to do? I am thinking
about when we call mark_page_accessed via touch_buffer, __find_get_block
etc. In those paths, is it not implied the buffer_heads are in active use
and releasing them would be counter-productive?

-- 
Mel Gorman
SUSE Labs

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