On 2016/7/18 16:05, Vlastimil Babka wrote: > On 07/18/2016 10:00 AM, Xishi Qiu wrote: >> On 2016/7/18 13:51, Joonsoo Kim wrote: >> >>> On Fri, Jul 15, 2016 at 10:47:06AM +0800, Xishi Qiu wrote: >>>> alloc_migrate_target() is called from migrate_pages(), and the page >>>> is always from user space, so we can add __GFP_HIGHMEM directly. >>> >>> No, all migratable pages are not from user space. For example, >>> blockdev file cache has __GFP_MOVABLE and migratable but it has no >>> __GFP_HIGHMEM and __GFP_USER. >>> >> >> Hi Joonsoo, >> >> So the original code "gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;" >> is not correct? > > It's not incorrect. GFP_USER just specifies some reclaim flags, and may > perhaps restrict allocation through __GFP_HARDWALL, where the original > page could have been allocated without the restriction. But it doesn't put > the place in an unexpected address range, as placing a non-highmem page into > highmem could. __GFP_MOVABLE then just controls a heuristic for placement > within a zone. > >>> And, zram's memory isn't GFP_HIGHUSER_MOVABLE but has __GFP_MOVABLE. >>> >> >> Can we distinguish __GFP_MOVABLE or GFP_HIGHUSER_MOVABLE when doing >> mem-hotplug? > > I don't understand the question here, can you rephrase with more detail? > Thanks. >
Hi Joonsoo, When we do memory offline, and the zone is movable zone, can we use "alloc_pages_node(nid, GFP_HIGHUSER_MOVABLE, 0);" to alloc a new page? the nid is the next node. Thanks, Xishi Qiu >> Thanks, >> Xishi Qiu >> >>> Thanks. >>> >>> >>> . >>> >> >> >> > > > . >
