At http://marc.info/?l=linux-acpi&m=135769405622667&w=2 thread, Toshi Kani mentioned as follows: "I have a question about the change you made in commit 65479472 in acpi_memhotplug.c. This change seems to require that acpi_memory_enable_device() calls add_memory() to add all memory ranges represented by memory device objects at boot-time, and keep the results be used for hot-remove. If I understand it right, this add_memory() call fails with EEXIST at boot-time since all memory ranges should have been added from EFI memory table (or e820) already. This results all memory ranges be marked as ! enabled & !failed. I think this means that we cannot hot-delete any memory ranges presented at boot-time since acpi_memory_remove_memory() only calls remove_memory() when the enabled flag is set. Is that correct?" Above mention is correct. Thus even if memory device supports hotplug, memory presented at boot-time cannot be hot removed since the memory device's acpi_memory_info->enabled is always 0. This patch changes to set 1 to "acpi_memory_info->enabled" of memory device presented at boot-time for hot removing the memory device. Signed-off-by: Yasuaki Ishimatsu --- v2 : Changed a based kernel from linux-3.9-rc2 to linux-pm.git/bleeding-edge. --- drivers/acpi/acpi_memhotplug.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c index d4f2eb8..ea78988 100644 --- a/drivers/acpi/acpi_memhotplug.c +++ b/drivers/acpi/acpi_memhotplug.c @@ -206,8 +206,8 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device) continue; } - if (!result) - info->enabled = 1; + info->enabled = 1; + /* * Add num_enable even if add_memory() returns -EEXIST, so the * device is bound to this driver. -- 1.7.1