Re: [PATCH] x86/mm/vmfault: Make vmalloc_fault() handle large pages

Since 4.1, ioremap() supports large page (pud/pmd) mappings in x86_64 and PAE. vmalloc_fault() however assumes that the vmalloc range is limited to pte mappings. pgd_ctor() sets the kernel's pgd entries to user's during fork(), which makes user processes share the same page tables for the kernel ranges. When a call to ioremap() is made at run-time that leads to allocate a new 2nd level table (pud in 64-bit and pmd in PAE), user process needs to re-sync with the updated kernel pgd entry with vmalloc_fault(). Following changes are made to vmalloc_fault().