[PATCH] riscv: Improve KASAN_VMALLOC support

When KASAN vmalloc region is populated, there is no userspace process and the page table in use is swapper_pg_dir, so there is no need to read SATP. Then we can use the same scheme used by kasan_populate_p*d functions to go through the page table, which harmonizes the code. In addition, make use o

Re: [PATCH] riscv: Improve KASAN_VMALLOC support

Hi Alexandre, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on next-20210226] [cannot apply to linus/master v5.11 v5.11-rc7 v5.11-rc6 v5.11] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--ba