18 Dec
2020
18 Dec
'20
12:24 p.m.
On Fri, Dec 18, 2020 at 4:43 AM Michal Hocko mhocko@suse.com wrote:
On Thu 17-12-20 13:52:38, Pavel Tatashin wrote:
* 1. Pinned pages: (long-term) pinning of movable pages is avoided* when pages are pinned and faulted, but it is still possible that* address space already has pages in ZONE_MOVABLE at the time when* pages are pinned (i.e. user has touches that memory before* pinning). In such case we try to migrate them to a different zone,* but if migration fails the pages can still end-up pinned in* ZONE_MOVABLE. In such case, memory offlining might retry a long* time and will only succeed once user application unpins pages.I still dislike this. Pinning can fail so there shouldn't be any reasons to break MOVABLE constrain for something that can be handled. If anything there should be a very good reasoning behind this decision documented.
This is basically current behaviour, after patch 8, we can never pin pages in the movable zone, so I will update this comment in that patch.
Thank you, Pasha
-- Michal Hocko SUSE Labs