[PATCH v3 11/13] arm64/efi: use plain memblock API for adding and removing reserved RAM

[Mark Salter]

On Tue, 2014-11-18 at 13:57 +0100, Ard Biesheuvel wrote:
> diff --git a/drivers/firmware/efi/virtmap.c
> b/drivers/firmware/efi/virtmap.c
> index 98735fb43581..4b6a5c31629f 100644
> --- a/drivers/firmware/efi/virtmap.c
> +++ b/drivers/firmware/efi/virtmap.c
> @@ -8,6 +8,7 @@
>   */
>  
>  #include <linux/efi.h>
> +#include <linux/memblock.h>
>  #include <linux/mm_types.h>
>  #include <linux/rbtree.h>
>  #include <linux/rwsem.h>
> @@ -97,8 +98,15 @@ void __init efi_virtmap_init(void)
>                 u64 paddr, npages, size;
>                 pgprot_t prot;
>  
> -               if (!efi_mem_is_usable_region(md))
> +               paddr = md->phys_addr;
> +               npages = md->num_pages;
> +               memrange_efi_to_native(&paddr, &npages);
> +               size = npages << PAGE_SHIFT;
> +
> +               if (!efi_mem_is_usable_region(md)) {
>                         efi_register_mem_resource(md);
> +                       memblock_remove(paddr, size);
> +               }

What exactly is the memblock_remove trying to accomplish? With it, I
get:

 Unable to handle kernel NULL pointer dereference at virtual address 00000008
 pgd = fffffe03d5890000
 [00000008] *pgd=00000043d5ae0003, *pud=00000043d5ae0003, *pmd=00000043d5ae0003, *pte=0000000000000000
 Internal error: Oops: 96000007 [#1] SMP
 Modules linked in:
 CPU: 0 PID: 107 Comm: modprobe Not tainted 3.18.0-rc5+ #8
 Hardware name: APM X-Gene Mustang board (DT)
 task: fffffe03d5770000 ti: fffffe03dd300000 task.ti: fffffe03dd300000
 PC is at mem_cgroup_begin_page_stat+0x40/0x110
 LR is at mem_cgroup_begin_page_stat+0x40/0x110
 pc : [<fffffe00001ec34c>] lr : [<fffffe00001ec34c>] pstate: 60000145
 sp : fffffe03dd303a80
 x29: fffffe03dd303a80 x28: 000000000000ffe0 
 x27: fffffdfef0f56bc0 x26: 0000000000000000 
 x25: 000003ff89b80000 x24: 0000000000000000 
 x23: fffffe03dd303ae8 x22: fffffe03dd303ae7 
 x21: 0000000000000000 x20: fffffe03d58a0420 
 x19: fffffdfef0004500 x18: 0000000000000000 
 x17: 000003ff89ba40dc x16: 000003ff89bbff90 
 x15: 000003ff89ba3b44 x14: 31313030343d6e66 
 x13: 7020303035343030 x12: 0000000000000006 
 x11: 0000000000000000 x10: 0000000000000186 
 x9 : 0000000000000187 x8 : 3030306665666466 
 x7 : fffffe0001041c18 x6 : 00000000000000ff 
 x5 : fffffe00004aaf20 x4 : fffffe00004b209c 
 x3 : 0000000000000000 x2 : 0000000000000000 
 x1 : fffffe0000f6a5d0 x0 : 0000000000000000 
 
 Process modprobe (pid: 107, stack limit = 0xfffffe03dd300058)
 Stack: (0xfffffe03dd303a80 to 0xfffffe03dd304000)
 3a80: dd303ac0 fffffe03 001c3e20 fffffe00 f0004500 fffffdfe d58a0420 fffffe03
 3aa0: f0004500 fffffdfe d58f4dc0 fffffe03 00000000 00000000 001b62d4 fffffe00
 3ac0: dd303af0 fffffe03 001b9984 fffffe00 01140f53 00200040 d58a0420 fffffe03
 3ae0: d5880000 fffffe03 d58a0420 fffffe03 dd303b40 fffffe03 001b9c4c fffffe00
 3b00: d58a0420 fffffe03 89b80000 000003ff f0f56bf0 fffffdfe 00000000 00000000
 ...
 3fa0: 89b907b7 000003ff 89bbf000 000003ff 89bc16e8 000003ff eb753490 000003ff
 3fc0: 89b91f9c 000003ff eb753490 000003ff 89b91fac 000003ff 20000000 00000000
 3fe0: 00000000 00000000 ffffffff ffffffff aaaaaaaa aaaaaaaa aaaaaaaa aaaaaaaa
 Call trace:
 [<fffffe00001ec34c>] mem_cgroup_begin_page_stat+0x40/0x110
 [<fffffe00001c3e1c>] page_add_file_rmap+0x24/0x80
 [<fffffe00001b9980>] do_set_pte+0x108/0x19c
 [<fffffe00001b9c48>] do_read_fault.isra.93+0x234/0x28c
 [<fffffe00001ba57c>] handle_mm_fault+0x488/0xd64
 [<fffffe00000a0ea0>] do_page_fault+0x224/0x358
 [<fffffe0000090128>] do_mem_abort+0x4c/0xb0
 Exception stack(0xfffffe03dd303e30 to 0xfffffe03dd303f50)
 3e20:                                     00000000 00000000 89bbf000 000003ff
 3e40: ffffffff ffffffff 89b91fac 000003ff 01043280 fffffe00 00000002 00000000
 3e60: dd303e70 fffffe03 008ce3a0 fffffe00 dd303e90 fffffe03 001c0400 fffffe00
 3e80: d5880000 fffffe03 000cbc60 fffffe00 eb753610 000003ff 00092fdc fffffe00
 3ea0: 00000000 00000000 89bbf000 000003ff ffffffff ffffffff 89ba4654 000003ff
 3ec0: 80000000 00000000 d5521480 fffffe03 89bc16e8 000003ff 89bc1a40 000003ff
 3ee0: 00000004 00000000 89b80000 000003ff fefefeff fefefefe 00000000 00000000
 3f00: 0000000f 00000000 89bc1028 000003ff 89ba7000 000003ff 0000079c 00000000
 3f20: 00400000 00000000 ffff0000 ffffffff 004038a0 00000000 00010000 00000000
 3f40: 89ba3c1c 000003ff 89ba3b44 000003ff
 Code: b9405835 35000275 aa1303e0 9400065c (f9400413)