Re: [rfc] [patch] mm: zone_reclaim fix for pseudo file systems

Ravikiran G Thirumalai
2007-07-31T01:56:47Z

On Mon, Jul 30, 2007 at 05:27:41PM -0700, Christoph Lameter wrote:
>On Mon, 30 Jul 2007, Andrew Morton wrote:
>
>> The problem is that __zone_reclaim() doesn't use all_unreclaimable at all.
>> You'll note that all the other callers of shrink_zone() do take avoiding
>> action if the zone is in all_unreclaimable state, but __zone_reclaim() forgot
>> to.
>
>zone reclaim only runs if there are unmapped file backed pages that can be
>reclaimed.

Yes, and in this case, without the patch, VM considers RAMFS pages to be
file backed, thus being fooled into entering reclaim. The process entering
into reclaim in our tests gets in through zone_reclaim.