On Wed, Feb 05, 2014 at 05:19:40PM +0100, Michal Hocko wrote: > On Wed 05-02-14 10:28:21, Johannes Weiner wrote: > > Here is the only exception to the above: swapout records maintain > > permanent css references, so they prevent css_free() from running. > > For that reason alone we should run one optimistic reparenting in > > css_offline() to make sure one swap record does not pin gigabytes of > > pages in an offlined cgroup, which is unreachable for reclaim. But > > How can reparenting help for swapped out pages? Or did you mean to at > least get rid of swapcache pages? I was thinking primarily of page cache. There could be a lot of it left in the group and once css_tryget() is disabled we can't reclaim it anymore. So we'd clean that out at offline time optimistically and at css_free() we catch any charges raced that showed up afterwards. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>