On Thu 17-12-20 13:52:41, Pavel Tatashin wrote: [...] > +#define PINNABLE_MIGRATE_MAX 10 > +#define PINNABLE_ISOLATE_MAX 100 Why would we need to limit the isolation retries. Those should always be temporary failure unless I am missing something. I am not sure about the PINNABLE_MIGRATE_MAX either. Why do we want to limit that? migrate_pages already implements its retry logic why do you want to count retries on top of that? I do agree that the existing logic is suboptimal because the migration failure might be ephemeral or permanent but that should be IMHO addressed at migrate_pages (resp. unmap_and_move) and simply report failures that are permanent - e.g. any potential pre-existing long term pin - if that is possible at all. If not what would cause permanent migration failure? OOM? -- Michal Hocko SUSE Labs
