From: Michal Hocko <mhocko@xxxxxxxx> Subject: mm, memory_hotplug: simplify empty node mask handling in new_node_page new_node_page tries to allocate the target page on a different NUMA node than the source page. This makes sense in most cases during the hotplug because we are likely to offline the whole numa node. But there are cases where there are no other nodes to fallback (e.g. when offlining parts of the only existing node) and we have to fallback to allocating from the source node. The current code does that but it can be simplified by checking the nmask and updating it before we even try to allocate rather than special casing it. This patch shouldn't introduce any functional change. Link: http://lkml.kernel.org/r/20170608074553.22152-2-mhocko@xxxxxxxxxx Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Cc: Xishi Qiu <qiuxishi@xxxxxxxxxx> Cc: zhong jiang <zhongjiang@xxxxxxxxxx> Cc: Joonsoo Kim <js1304@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memory_hotplug.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff -puN mm/memory_hotplug.c~mm-memory_hotplug-simplify-empty-node-mask-handling-in-new_node_page mm/memory_hotplug.c --- a/mm/memory_hotplug.c~mm-memory_hotplug-simplify-empty-node-mask-handling-in-new_node_page +++ a/mm/memory_hotplug.c @@ -1436,7 +1436,15 @@ static struct page *new_node_page(struct gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE; int nid = page_to_nid(page); nodemask_t nmask = node_states[N_MEMORY]; - struct page *new_page = NULL; + + /* + * try to allocate from a different node but reuse this node if there + * are no other online nodes to be used (e.g. we are offlining a part + * of the only existing node) + */ + node_clear(nid, nmask); + if (nodes_empty(nmask)) + node_set(nid, nmask); /* * TODO: allocate a destination hugepage from a nearest neighbor node, @@ -1447,18 +1455,11 @@ static struct page *new_node_page(struct return alloc_huge_page_node(page_hstate(compound_head(page)), next_node_in(nid, nmask)); - node_clear(nid, nmask); - if (PageHighMem(page) || (zone_idx(page_zone(page)) == ZONE_MOVABLE)) gfp_mask |= __GFP_HIGHMEM; - if (!nodes_empty(nmask)) - new_page = __alloc_pages_nodemask(gfp_mask, 0, nid, &nmask); - if (!new_page) - new_page = __alloc_pages(gfp_mask, 0, nid); - - return new_page; + return __alloc_pages_nodemask(gfp_mask, 0, nid, &nmask); } #define NR_OFFLINE_AT_ONCE_PAGES (256) _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
