• Oscar Salvador's avatar
    kernel, resource: check for IORESOURCE_SYSRAM in release_mem_region_adjustable · 65c78784
    Oscar Salvador authored
    This is a preparation for the next patch.
    
    Currently, we only call release_mem_region_adjustable() in __remove_pages
    if the zone is not ZONE_DEVICE, because resources that belong to HMM/devm
    are being released by themselves with devm_release_mem_region.
    
    Since we do not want to touch any zone/page stuff during the removing of
    the memory (but during the offlining), we do not want to check for the
    zone here.  So we need another way to tell release_mem_region_adjustable()
    to not realease the resource in case it belongs to HMM/devm.
    
    HMM/devm acquires/releases a resource through
    devm_request_mem_region/devm_release_mem_region.
    
    These resources have the flag IORESOURCE_MEM, while resources acquired by
    hot-add memory path (register_memory_resource()) contain
    IORESOURCE_SYSTEM_RAM.
    
    So, we can check for this flag in release_mem_region_adjustable, and if
    the resource does not contain such flag, we know that we are dealing with
    a HMM/devm resource, so we can back off.
    
    Link: http://lkml.kernel.org/r/20181127162005.15833-3-osalvador@suse.deSigned-off-by: 's avatarOscar Salvador <osalvador@suse.de>
    Reviewed-by: 's avatarDavid Hildenbrand <david@redhat.com>
    Reviewed-by: 's avatarPavel Tatashin <pasha.tatashin@soleen.com>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: Jerome Glisse <jglisse@redhat.com>
    Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
    Cc: Michal Hocko <mhocko@suse.com>
    Cc: Oscar Salvador <osalvador@suse.com>
    Cc: "Rafael J. Wysocki" <rafael@kernel.org>
    Signed-off-by: 's avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
    65c78784