On Wed, 4 Nov 2015 18:20:14 +0800
Xishi Qiu <[email protected]> wrote:
> On 2015/11/4 16:23, liuchangsheng wrote:
>
> > After the user config CONFIG_MOVABLE_NODE,
> > When the memory is hot added, should_add_memory_movable() return 0
> > because all zones including ZONE_MOVABLE are empty,
> > so the memory that was hot added will be assigned to ZONE_NORMAL,
> > and we need using the udev rules to online the memory automatically:
> > SUBSYSTEM=="memory", ACTION=="add", ATTR{state}=="offline",
> > ATTR{state}="online_movable"
> > The memory block onlined by udev must be adjacent to ZONE_MOVABLE.
> > The events of memory section are notified to udev asynchronously,
>
> Hi Yasuaki,
>
> If udev onlines memory in descending order, like 3->2->1->0, it will
> success, but we notifiy to udev in ascending order, like 0->1->2->3,
> so the udev rules cannot online memory as movable, right?
right.
>
> > so it can not ensure that the memory block onlined by udev is
> > adjacent to ZONE_MOVABLE.So it can't ensure memory online always success.
> > But we want the whole node to be added to ZONE_MOVABLE by default.
> >
> > So we change should_add_memory_movable(): if the user config
> > CONFIG_MOVABLE_NODE and movable_node kernel option
> > and the ZONE_NORMAL is empty or the pfn of the hot-added memory
> > is after the end of the ZONE_NORMAL it will always return 1
> > and then the whole node will be added to ZONE_MOVABLE by default.
> > If we want the node to be assigned to ZONE_NORMAL,
> > we can do it as follows:
> > "echo online_kernel > /sys/devices/system/memory/memoryXXX/state"
> >
>
> The order should like 0->1->2->3, right? 3->2->1->0 will be failed.
right.
Thanks,
Yasuaki Ishimatsu
>
> > Signed-off-by: liuchangsheng <[email protected]>
> > Signed-off-by: Xiaofeng Yan <[email protected]>
> > Tested-by: Dongdong Fan <[email protected]>
> > Reviewed-by: <[email protected]>
> > Cc: Wang Nan <[email protected]>
> > Cc: Dave Hansen <[email protected]>
> > Cc: Yinghai Lu <[email protected]>
> > Cc: Tang Chen <[email protected]>
> > Cc: Yasuaki Ishimatsu <[email protected]>
> > Cc: Toshi Kani <[email protected]>
> > Cc: Xishi Qiu <[email protected]>
> > ---
> > mm/memory_hotplug.c | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> > index aa992e2..8617b9f 100644
> > --- a/mm/memory_hotplug.c
> > +++ b/mm/memory_hotplug.c
> > @@ -1201,6 +1201,9 @@ static int check_hotplug_memory_range(u64 start, u64
> > size)
> > /*
> > * If movable zone has already been setup, newly added memory should be
> > check.
> > * If its address is higher than movable zone, it should be added as
> > movable.
> > + * And if system boots up with movable_node and config CONFIG_MOVABLE_NOD
> > and
> > + * added memory does not overlap the zone before MOVABLE_ZONE,
> > + * the memory is added as movable.
> > * Without this check, movable zone may overlap with other zone.
> > */
> > static int should_add_memory_movable(int nid, u64 start, u64 size)
> > @@ -1208,6 +1211,10 @@ 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 *pre_zone = pgdat->node_zones + (ZONE_MOVABLE - 1);
> > +
> > + if (movable_node_is_enabled() && (zone_end_pfn(pre_zone) <= start_pfn))
> > + return 1;
> >
>
> Looks good to me.
>
> How about add some comment in mm/Kconfig?
>
> Thanks,
> Xishi Qiu
>
> > if (zone_is_empty(movable_zone))
> > return 0;
>
>
>
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