Messages in this thread | | | Subject | Re: [PATCH V4] mm: memory hot-add: memory can not be added to movable zone defaultly | From | Vlastimil Babka <> | Date | Mon, 31 Aug 2015 15:08:56 +0200 |
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On 08/31/2015 07:58 AM, Changsheng Liu wrote: > From: Changsheng Liu <liuchangcheng@inspur.com> > > After the user config CONFIG_MOVABLE_NODE and movable_node kernel option, > When the memory is hot added, should_add_memory_movable() return 0 > because all zones including movable zone are empty, > so the memory that was hot added will be added to the normal zone > and the normal zone will be created firstly. > But we want the whole node to be added to movable zone defaultly. > > So we change should_add_memory_movable(): if the user config > CONFIG_MOVABLE_NODE and movable_node kernel option > it will always return 1 and all zones is empty at the same time, > so that the movable zone will be created firstly > and then the whole node will be added to movable zone defaultly. > If we want the node to be added to normal zone, > we can do it as follows: > "echo online_kernel > /sys/devices/system/memory/memoryXXX/state" > > If the memory is added to movable zone defaultly, > the user can offline it and add it to other zone again. > But if the memory is added to normal zone defaultly, > the user will not offline the memory used by kernel. > > Reviewed-by: Andrew Morton <akpm@linux-foundation.org> > Reviewed-by: Yasuaki Ishimatsu <yasu.isimatu@gmail.com> > Reviewed-by: Vlastimil Babka <vbabka@suse.cz> > Reviewed-by: Xiaofeng Yan <yanxiaofeng@inspur.com>
Thanks for the credit for commenting on the previous versions of the patch. However, "Reviewed-by" currently means that the reviewer believes the patch is OK, so you can add it only if the reviewer offers it explicitly. See Documentation/SubmittingPatches section 13. There was a discussion on ksummit-discuss about adding a new tag for this case, but nothing was decided yet AFAIK.
> Signed-off-by: Changsheng Liu <liuchangcheng@inspur.com> > Tested-by: Dongdong Fan <fandd@inspur.com> > --- > mm/memory_hotplug.c | 5 +++++ > 1 files changed, 5 insertions(+), 0 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 26fbba7..d1149ff 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1197,6 +1197,11 @@ static int should_add_memory_movable(int nid, u64 start, u64 size) > unsigned long start_pfn = start >> PAGE_SHIFT; > pg_data_t *pgdat = NODE_DATA(nid); > struct zone *movable_zone = pgdat->node_zones + ZONE_MOVABLE; > + struct zone *normal_zone = pgdat->node_zones + ZONE_NORMAL; > + > + if (movable_node_is_enabled() > + && (zone_end_pfn(normal_zone) <= start_pfn)) > + return 1;
I wonder if the condition is true and ZONE_NORMAL exists (but it's empty?) if you intend to only add movable memory to a node, so you can still hot-remove it all with this patch?
> > if (zone_is_empty(movable_zone)) > return 0; >
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