In sparse_init() we allocate two large buffers to temporary hold usemap and memmap for the whole machine. However, we can avoid doing that if we changed sparse_init() to operated on per-node bases instead of doing it on the whole machine beforehand. As shown by Baoquan http://lkml.kernel.org/r/20180628062857.29658-1-bhe@xxxxxxxxxx The buffers are large enough to cause machine stop to boot on small memory systems. These patches should be applied on top of Baoquan's work, as CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER is removed in that work. For the ease of review, I split this work so the first patch only adds new interfaces, the second patch enables them, and removes the old ones. Pavel Tatashin (2): mm/sparse: add sparse_init_nid() mm/sparse: start using sparse_init_nid(), and remove old code include/linux/mm.h | 9 +- mm/sparse-vmemmap.c | 44 ++++--- mm/sparse.c | 285 ++++++++++++++------------------------------ 3 files changed, 125 insertions(+), 213 deletions(-) -- 2.18.0
