From: Chris Wilson <ch...@chris-wilson.co.uk> Date: Mon, 9 Jan 2017 11:37:07 +0000
> Could some mm expert explain why it is safe for mm/vmalloc.c to ignore > huge pud/pmd that raise BUG_ON in the same code in mm/memory.c > (vmap_pmd_range() vs apply_to_pmd_range())? > > At a guess, is sparc64 covering the init_mm with a huge zero page? How > is it then meant to be split? Something like We map the linear physical area (PAGE_OFFSET --> PAGE_OFFSET + max_phys_addr) using huge pages unless DEBUG_PAGEALLOC is enabled. It is not meant to be split, and that's why we don't use huge pages when DEBUG_PAGEALLOC is set since that requires changes to the mapping to be possible.
