Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace

From: Michal Hocko
Date: Wed May 04 2016 - 05:24:07 EST

On Wed 04-05-16 11:35:00, Joonsoo Kim wrote:
> Oops... I think more deeply and change my mind. In recursion case,
> stack is consumed more than 1KB and it would be a problem. I think
> that best approach is using preallocated per cpu entry. It will also
> close recursion detection issue by paying interrupt on/off overhead.

I was thinking about per-cpu solution as well but the thing is that the
stackdepot will allocate and until you drop __GFP_DIRECT_RECLAIM then
per-cpu is not safe. I haven't checked the implamentation of
depot_save_stack but I assume it will not schedule in other places.
Michal Hocko