• Vitaly Kuznetsov's avatar
    memory-hotplug: add automatic onlining policy for the newly added memory · 31bc3858
    Vitaly Kuznetsov authored
    Currently, all newly added memory blocks remain in 'offline' state
    unless someone onlines them, some linux distributions carry special udev
    rules like:
      SUBSYSTEM=="memory", ACTION=="add", ATTR{state}=="offline", ATTR{state}="online"
    to make this happen automatically.  This is not a great solution for
    virtual machines where memory hotplug is being used to address high
    memory pressure situations as such onlining is slow and a userspace
    process doing this (udev) has a chance of being killed by the OOM killer
    as it will probably require to allocate some memory.
    Introduce default policy for the newly added memory blocks in
    /sys/devices/system/memory/auto_online_blocks file with two possible
    values: "offline" which preserves the current behavior and "online"
    which causes all newly added memory blocks to go online as soon as
    they're added.  The default is "offline".
    Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
    Reviewed-by: default avatarDaniel Kiper <daniel.kiper@oracle.com>
    Cc: Jonathan Corbet <corbet@lwn.net>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: Daniel Kiper <daniel.kiper@oracle.com>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: Tang Chen <tangchen@cn.fujitsu.com>
    Cc: David Vrabel <david.vrabel@citrix.com>
    Acked-by: default avatarDavid Rientjes <rientjes@google.com>
    Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
    Cc: Xishi Qiu <qiuxishi@huawei.com>
    Cc: Mel Gorman <mgorman@techsingularity.net>
    Cc: "K. Y. Srinivasan" <kys@microsoft.com>
    Cc: Igor Mammedov <imammedo@redhat.com>
    Cc: Kay Sievers <kay@vrfy.org>
    Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
memory-hotplug.txt 17.9 KB