On Wed 24-05-17 15:30:17, Igor Mammedov wrote: > On Wed, 24 May 2017 14:24:11 +0200 > Michal Hocko <[email protected]> wrote: > > [...] > > index facc20a3f962..ec7d6ae01c96 100644 > > --- a/Documentation/admin-guide/kernel-parameters.txt > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > @@ -2246,8 +2246,11 @@ > [...] > > + movable. This means that the memory of such nodes > > + will be usable only for movable allocations which > > + rules out almost all kernel allocations. Use with > > + caution! > maybe dumb question but, is it really true that kernel won't ever > do kernel allocations from movable zone? > > looking at kmalloc(slab): we can get here: > > get_page_from_freelist() -> > rmqueue() -> > __rmqueue() -> > __rmqueue_fallback() -> > find_suitable_fallback() > > and it might return movable fallback and page could be stolen from there.
No, you are mixing movable/unmovable pageblocks and movable zones. Movable zone basically works the same way as the Highmem zone. Have a look at gfp_zone() and high_zoneidx usage in get_page_from_freelist -- Michal Hocko SUSE Labs
