• Pavel Tatashin's avatar
    device-dax: "Hotremove" persistent memory that is used like normal RAM · 9f960da7
    Pavel Tatashin authored
    It is now allowed to use persistent memory like a regular RAM, but
    currently there is no way to remove this memory until machine is
    This work expands the functionality to also allows hotremoving
    previously hotplugged persistent memory, and recover the device for use
    for other purposes.
    To hotremove persistent memory, the management software must first
    offline all memory blocks of dax region, and than unbind it from
    device-dax/kmem driver.  So, operations should look like this:
      echo offline > /sys/devices/system/memory/memoryN/state
      echo dax0.0 > /sys/bus/dax/drivers/kmem/unbind
    Note: if unbind is done without offlining memory beforehand, it won't be
    possible to do dax0.0 hotremove, and dax's memory is going to be part of
    System RAM until reboot.
    Link: http://lkml.kernel.org/r/20190517215438.6487-4-pasha.tatashin@soleen.comSigned-off-by: default avatarPavel Tatashin <pasha.tatashin@soleen.com>
    Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
    Cc: James Morris <jmorris@namei.org>
    Cc: Sasha Levin <sashal@kernel.org>
    Cc: Michal Hocko <mhocko@suse.com>
    Cc: Dave Hansen <dave.hansen@linux.intel.com>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: Keith Busch <keith.busch@intel.com>
    Cc: Vishal Verma <vishal.l.verma@intel.com>
    Cc: Dave Jiang <dave.jiang@intel.com>
    Cc: Ross Zwisler <zwisler@kernel.org>
    Cc: Tom Lendacky <thomas.lendacky@amd.com>
    Cc: Huang Ying <ying.huang@intel.com>
    Cc: Fengguang Wu <fengguang.wu@intel.com>
    Cc: Borislav Petkov <bp@suse.de>
    Cc: Bjorn Helgaas <bhelgaas@google.com>
    Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
    Cc: Takashi Iwai <tiwai@suse.de>
    Cc: Jérôme Glisse <jglisse@redhat.com>
    Cc: Dave Hansen <dave.hansen@intel.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
kmem.c 3.91 KB