On Mon 26-06-17 11:58:22, Wei Yang wrote: > In commit (9adb62a5df9c0fbef7) "mm/hotplug: correctly setup fallback > zonelists when creating new pgdat" tries to build the correct zonelist for > a new added node, while it is not necessary to rebuild it for already exist > nodes. > > In build_zonelists(), it will iterate on nodes with memory. For a new added > node, it will have memory until node_states_set_node() is called in > online_pages(). > > This patch will avoid to rebuild the zonelists for already exist nodes.
It is not very clear from the changelog why that actually matters. The only effect I can see is that other zonelists on other online nodes will not learn about the currently memory less node. This is a good think because we do not pointlessly try to allocate from that node. > Signed-off-by: Wei Yang <[email protected]> Acked-by: Michal Hocko <[email protected]> > --- > mm/page_alloc.c | 16 +++++++++------- > 1 file changed, 9 insertions(+), 7 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 560eafe8234d..fc8181b44fd8 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -5200,15 +5200,17 @@ static int __build_all_zonelists(void *data) > memset(node_load, 0, sizeof(node_load)); > #endif > > - if (self && !node_online(self->node_id)) { > + /* This node is hotadded and no memory preset yet. > + * So just build zonelists is fine, no need to touch other nodes. > + */ This comment doesn't make much sense to me. What about /* * Do not rebuild zonelists on all online nodes if the current * node is not online yet (it doesn't have any memory) and * allocating from it is pointless. Still build zonelist for * self because we need to handle memoryless nodes. */ > + if (self && !node_online(self->node_id)) > build_zonelists(self); > - } > - > - for_each_online_node(nid) { > - pg_data_t *pgdat = NODE_DATA(nid); > + else > + for_each_online_node(nid) { > + pg_data_t *pgdat = NODE_DATA(nid); > > - build_zonelists(pgdat); > - } > + build_zonelists(pgdat); > + } > > /* > * Initialize the boot_pagesets that are going to be used > -- > 2.11.0 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to [email protected]. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"[email protected]";> [email protected] </a> -- Michal Hocko SUSE Labs
