Re: [PATCH 0/5] memory-hotplug: suitable memory should go to ZONE_MOVABLE

Zhang Yanfei
2014-07-18T09:17:46Z

Hello,

On 07/18/2014 03:55 PM, Wang Nan wrote:
> This series of patches fix a problem when adding memory in bad manner.
> For example: for a x86_64 machine booted with "mem=400M" and with 2GiB
> memory installed, following commands cause problem:
>
> # echo 0x40000000 > /sys/devices/system/memory/probe
> [ 28.613895] init_memory_mapping: [mem 0x40000000-0x47ffffff]
> # echo 0x48000000 > /sys/devices/system/memory/probe
> [ 28.693675] init_memory_mapping: [mem 0x48000000-0x4fffffff]
> # echo online_movable > /sys/devices/system/memory/memory9/state
> # echo 0x50000000 > /sys/devices/system/memory/probe
> [ 29.084090] init_memory_mapping: [mem 0x50000000-0x57ffffff]
> # echo 0x58000000 > /sys/devices/system/memory/probe
> [ 29.151880] init_memory_mapping: [mem 0x58000000-0x5fffffff]
> # echo online_movable > /sys/devices/system/memory/memory11/state
> # echo online> /sys/devices/system/memory/memory8/state
> # echo online> /sys/devices/system/memory/memory10/state
> # echo offline> /sys/devices/system/memory/memory9/state
> [ 30.558819] Offlined Pages 32768
> # free
> total used free shared buffers cached
> Mem: 780588 18014398509432020 830552 0 0 51180
> -/+ buffers/cache: 18014398509380840 881732
> Swap: 0 0 0
>
> This is because the above commands probe higher memory after online a
> section with online_movable, which causes ZONE_HIGHMEM (or ZONE_NORMAL
> for systems without ZONE_HIGHMEM) overlaps ZONE_MOVABLE.

Yeah, this is rare in reality but can happen. Could you please also
include the free result and zoneinfo after applying your patch?

Thanks.

>
> After the second online_movable, the problem can be observed from
> zoneinfo:
>
> # cat /proc/zoneinfo
> ...
> Node 0, zone Movable
> pages free 65491
> min 250
> low 312
> high 375
> scanned 0
> spanned 18446744073709518848
> present 65536
> managed 65536
> ...
>
> This series of patches solve the problem by checking ZONE_MOVABLE when
> choosing zone for new memory. If new memory is inside or higher than
> ZONE_MOVABLE, makes it go there instead.
>
>
> Wang Nan (5):
> memory-hotplug: x86_64: suitable memory should go to ZONE_MOVABLE
> memory-hotplug: x86_32: suitable memory should go to ZONE_MOVABLE
> memory-hotplug: ia64: suitable memory should go to ZONE_MOVABLE
> memory-hotplug: sh: suitable memory should go to ZONE_MOVABLE
> memory-hotplug: powerpc: suitable memory should go to ZONE_MOVABLE
>
> arch/ia64/mm/init.c | 7 +++++++
> arch/powerpc/mm/mem.c | 6 ++++++
> arch/sh/mm/init.c | 13 ++++++++-----
> arch/x86/mm/init_32.c | 6 ++++++
> arch/x86/mm/init_64.c | 10 ++++++++--
> 5 files changed, 35 insertions(+), 7 deletions(-)
>

--
Thanks.
Zhang Yanfei