• Dennis Chen's avatar
    mm/memblock.c: add new infrastructure to address the mem limit issue · a571d4eb
    Dennis Chen authored
    In some cases, memblock is queried by kernel to determine whether a
    specified address is RAM or not.  For example, the ACPI core needs this
    information to determine which attributes to use when mapping ACPI
    regions(acpi_os_ioremap).  Use of incorrect memory types can result in
    faults, data corruption, or other issues.
    
    Removing memory with memblock_enforce_memory_limit() throws away this
    information, and so a kernel booted with 'mem=' may suffer from the
    issues described above.  To avoid this, we need to keep those NOMAP
    regions instead of removing all above the limit, which preserves the
    information we need while preventing other use of those regions.
    
    This patch adds new infrastructure to retain all NOMAP memblock regions
    while removing others, to cater for this.
    
    Link: http://lkml.kernel.org/r/1468475036-5852-2-git-send-email-dennis.chen@arm.comSigned-off-by: 's avatarDennis Chen <dennis.chen@arm.com>
    Acked-by: 's avatarSteve Capper <steve.capper@arm.com>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
    Cc: Pekka Enberg <penberg@kernel.org>
    Cc: Mel Gorman <mgorman@techsingularity.net>
    Cc: Tang Chen <tangchen@cn.fujitsu.com>
    Cc: Tony Luck <tony.luck@intel.com>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Rafael J. Wysocki <rafael@kernel.org>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: Mark Rutland <mark.rutland@arm.com>
    Cc: Matt Fleming <matt@codeblueprint.co.uk>
    Cc: Kaly Xin <kaly.xin@arm.com>
    Signed-off-by: 's avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
    a571d4eb
memblock.h 14 KB