On Wed, 28 Feb 2018 11:26:53 +0800 Baoquan He <bhe@xxxxxxxxxx> wrote: > This is v3 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. This patchset could do with some more review, please?
