On 02/22/18 at 05:11pm, Baoquan He wrote: > This is v2 post. V1 can be found here: > https://www.spinics.net/lists/linux-mm/msg144486.html > > In sparse_init(), two temporary pointer arrays, usemap_map and map_map > are allocated with the size of NR_MEM_SECTIONS. They are used to store > each memory section's usemap and mem map if marked as present. In > 5-level paging mode, this will cost 512M memory though they will be > released at the end of sparse_init(). System with few memory, like > kdump kernel which usually only has about 256M, will fail to boot > because of allocation failure if CONFIG_X86_5LEVEL=y. > > In this patchset, optimize the memmap allocation code to only use > usemap_map and map_map with the size of nr_present_sections. This > makes kdump kernel boot up with normal crashkernel='' setting when > CONFIG_X86_5LEVEL=y. Sorry, forgot adding the change log. v1-v2: Split out the nr_present_sections adding as a single patch for easier reviewing. Rewrite patch log according to Dave's suggestion. Fix code bug in patch 0002 reported by test robot. > > Baoquan He (3): > mm/sparse: Add a static variable nr_present_sections > mm/sparsemem: Defer the ms->section_mem_map clearing > mm/sparse: Optimize memmap allocation during sparse_init() > > mm/sparse-vmemmap.c | 9 +++++---- > mm/sparse.c | 54 +++++++++++++++++++++++++++++++++++------------------ > 2 files changed, 41 insertions(+), 22 deletions(-) > > -- > 2.13.6 > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
