On Wed, Aug 22, 2018 at 11:32:26AM +0200, Oscar Salvador wrote: > From: Oscar Salvador <osalvador@xxxxxxx> > > This patch tries to simplify node_states_check_changes_offline > and make the code more understandable by: > > - Removing the if (N_MEMORY == N_NORMAL_MEMORY) wrong statement > - Removing the if (N_MEMORY == N_HIGH_MEMORY) wrong statement > - Re-structure the code a bit > - Removing confusing comments > > Signed-off-by: Oscar Salvador <osalvador@xxxxxxx> I realized I made a mistake here. I was not counting the present pages correctly. I will send a new version after the merge-windows gets closed. Sorry for the noise For the sake of clarity, the patch should have been: --- diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 006a7b817724..bca11da4e11f 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1487,23 +1487,12 @@ static void node_states_check_changes_offline(unsigned long nr_pages, enum zone_type zt, zone_last = ZONE_NORMAL; /* - * If we have HIGHMEM or movable node, node_states[N_NORMAL_MEMORY] - * contains nodes which have zones of 0...ZONE_NORMAL, - * set zone_last to ZONE_NORMAL. - * - * If we don't have HIGHMEM nor movable node, - * node_states[N_NORMAL_MEMORY] contains nodes which have zones of - * 0...ZONE_MOVABLE, set zone_last to ZONE_MOVABLE. - */ - if (N_MEMORY == N_NORMAL_MEMORY) - zone_last = ZONE_MOVABLE; - - /* - * check whether node_states[N_NORMAL_MEMORY] will be changed. - * If the memory to be offline is in a zone of 0...zone_last, - * and it is the last present memory, 0...zone_last will - * become empty after offline , thus we can determind we will - * need to clear the node from node_states[N_NORMAL_MEMORY]. + * If the current zone is whithin (0..ZONE_NORMAL], + * check if the amount of pages that are going to be + * offlined is above or equal to the sum of the present + * pages of these zones. + * If that happens, we need to take this node out of + * node_state[N_NORMAL_MEMORY] */ for (zt = 0; zt <= zone_last; zt++) present_pages += pgdat->node_zones[zt].present_pages; @@ -1514,21 +1503,15 @@ static void node_states_check_changes_offline(unsigned long nr_pages, #ifdef CONFIG_HIGHMEM /* - * If we have movable node, node_states[N_HIGH_MEMORY] - * contains nodes which have zones of 0...ZONE_HIGHMEM, - * set zone_last to ZONE_HIGHMEM. - * - * If we don't have movable node, node_states[N_NORMAL_MEMORY] - * contains nodes which have zones of 0...ZONE_MOVABLE, - * set zone_last to ZONE_MOVABLE. + * If the current zone is whithin (0..ZONE_HIGHMEM], check if + * the amount of pages that are going to be offlined is above + * or equal to the sum of the present pages of these zones. + * If that happens, we need to take this node out of + * node_state[N_HIGH_MEMORY] */ - zone_last = ZONE_HIGHMEM; - if (N_MEMORY == N_HIGH_MEMORY) - zone_last = ZONE_MOVABLE; - - for (; zt <= zone_last; zt++) - present_pages += pgdat->node_zones[zt].present_pages; - if (zone_idx(zone) <= zone_last && nr_pages >= present_pages) + zt = ZONE_HIGHMEM; + present_pages += pgdat->node_zones[zt].present_pages; + if (zone_idx(zone) <= zt && nr_pages >= present_pages) arg->status_change_nid_high = zone_to_nid(zone); else arg->status_change_nid_high = -1; @@ -1541,18 +1524,14 @@ static void node_states_check_changes_offline(unsigned long nr_pages, #endif /* - * node_states[N_HIGH_MEMORY] contains nodes which have 0...ZONE_MOVABLE + * Count pages from ZONE_MOVABLE as well. + * If the amount of pages that are going to be offlined is above + * or equal the sum of the present pages of all zones, we need + * to remove this node from node_state[N_MEMORY] */ - zone_last = ZONE_MOVABLE; + zt = ZONE_MOVABLE; + present_pages += pgdat->node_zones[zt].present_pages; - /* - * check whether node_states[N_HIGH_MEMORY] will be changed - * If we try to offline the last present @nr_pages from the node, - * we can determind we will need to clear the node from - * node_states[N_HIGH_MEMORY]. - */ - for (; zt <= zone_last; zt++) - present_pages += pgdat->node_zones[zt].present_pages; if (nr_pages >= present_pages) arg->status_change_nid = zone_to_nid(zone); else -- Oscar Salvador SUSE L3
