• Joonsoo Kim's avatar
    mm, vmalloc: iterate vmap_area_list, instead of vmlist, in vmallocinfo() · d4033afd
    Joonsoo Kim authored
    This patch is a preparatory step for removing vmlist entirely.  For
    above purpose, we change iterating a vmap_list codes to iterating a
    vmap_area_list.  It is somewhat trivial change, but just one thing
    should be noticed.
    
    Using vmap_area_list in vmallocinfo() introduce ordering problem in SMP
    system.  In s_show(), we retrieve some values from vm_struct.
    vm_struct's values is not fully setup when va->vm is assigned.  Full
    setup is notified by removing VM_UNLIST flag without holding a lock.
    When we see that VM_UNLIST is removed, it is not ensured that vm_struct
    has proper values in view of other CPUs.  So we need smp_[rw]mb for
    ensuring that proper values is assigned when we see that VM_UNLIST is
    removed.
    
    Therefore, this patch not only change a iteration list, but also add a
    appropriate smp_[rw]mb to right places.
    Signed-off-by: default avatarJoonsoo Kim <js1304@gmail.com>
    Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
    Cc: Chris Metcalf <cmetcalf@tilera.com>
    Cc: Dave Anderson <anderson@redhat.com>
    Cc: Eric Biederman <ebiederm@xmission.com>
    Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Vivek Goyal <vgoyal@redhat.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    d4033afd
vmalloc.c 68.2 KB