On Tue, Feb 15, 2022 at 10:17:09AM +0530, Anshuman Khandual wrote: > Hi Alistair, > > On 2/15/22 8:28 AM, Alistair Popple wrote: > > ZONE_MOVABLE uses the remaining memory in each node. It's starting pfn > > is also aligned to MAX_ORDER_NR_PAGES. It is possible for the remaining > > memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is > > not enough room for ZONE_MOVABLE on that node. CC Mel as he wrote that back then. I was curious about the commit that introduced that, and I found [1] and [2]. I guess [2] was eventually dismissed in favor of [1] as a whole, but in there the commit message said: "This patch rounds the start of ZONE_MOVABLE in each node to a MAX_ORDER_NR_PAGES boundary. If the rounding pushes the start of ZONE_MOVABLE above the end of the node then the zone will contain no memory and will not be used at runtime" I might be missing something, but it just rounds up the value, but does not check if it falls beyond node's boundaries. [1] commit 2a1e274acf0b1c192face19a4be7c12d4503eaaf "Create the ZONE_MOVABLE zone" [2] https://marc.info/?l=linux-mm&m=117743777129526&w=2 -- Oscar Salvador SUSE Labs
