[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH] mm, page_alloc: fix build_zonerefs_node()
On Thu 07-04-22 12:45:41, Juergen Gross wrote: > On 07.04.22 12:34, Michal Hocko wrote: > > Ccing Mel > > > > On Thu 07-04-22 11:32:21, Juergen Gross wrote: > > > Since commit 9d3be21bf9c0 ("mm, page_alloc: simplify zonelist > > > initialization") only zones with free memory are included in a built > > > zonelist. This is problematic when e.g. all memory of a zone has been > > > ballooned out. > > > > What is the actual problem there? > > When running as Xen guest new hotplugged memory will not be onlined > automatically, but only on special request. This is done in order to > support adding e.g. the possibility to use another GB of memory, while > adding only a part of that memory initially. > > In case adding that memory is populating a new zone, the page allocator > won't be able to use this memory when it is onlined, as the zone wasn't > added to the zonelist, due to managed_zone() returning 0. How is that memory onlined? Because "regular" onlining (online_pages()) does rebuild zonelists if their zone hasn't been populated before. -- Michal Hocko SUSE Labs
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