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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>