Grub BADRAM doesn't blacklist special memory range

I have a laptop with a damaged integrated RAM, so I ran memtest86+ to get the affected sectors and marked them as unusable. The issue came when modifying the grub configuration. I set the GRUB_BADRAM option as GRUB_BADRAM="0x086580000,0xffff80000,0x0bb1c0000,0xffff00000,0x0bfa40000,0xffffc0000" Checking /proc/iomem I could see that no blacklist was being applied as it outputted the line 5f000000-dfffffff : Reserved I decided to see the difference between the iomem file with no blacklist and the one with the BAD_RAM option and the only difference was the address where the kernel code was stored, which, as I am aware, is decided at random on every boot, so there was no effective difference at all. Also, I was still experiencing the same memory related troubles as before, where some programs would crash due to a SIGSEGV, even my Desktop Environment or GCC. Thinking I did something wrong, I chose to change the memory addresses to 4 GB later (starting at address 0x186580000 and so on) and to my surprise it did block them, as I could see 186580000-1865fffff : Unusable memory 186600000-1bb0fffff : System RAM 1bb100000-1bb1fffff : Unusable memory 1bb200000-1bfa3ffff : System RAM 1bfa40000-1bfa7ffff : Unusable memory 1bfa80000-41f33ffff : System RAM So this time the change was being applied. All of this makes me question, was the first blacklist happening at all? Was iomem just not showing the blacklist range due to some hierarchy? Or even, is there some range that cannot be affected by GRUB_BADRAM?