[PATCH] remove the initrd resource in /proc/iomem as the initrd has freed the reserved memblock.

From: Yi Wang
Date: Tue Jul 02 2019 - 06:37:20 EST

From: Junhua Huang <huang.junhua@xxxxxxxxxx>

The 'commit 50d7ba36b916 ("arm64: export memblock_reserve()d regions via /proc/iomem")'
show the reserved memblock in /proc/iomem. But the initrd's reserved memblock
will be freed in free_initrd_mem(), which executes after the reserve_memblock_reserved_regions().
So there are some incorrect information shown in /proc/iomem. e.g.:
80000000-bbdfffff : System RAM
80080000-813effff : Kernel code
813f0000-8156ffff : reserved
81570000-817fcfff : Kernel data
83400000-83ffffff : reserved
90000000-90004fff : reserved
b0000000-b2618fff : reserved
b8c00000-bbbfffff : reserved
In this case, the range from b0000000 to b2618fff is reserved for initrd, which should be
clean from the resource tree after it was freed. As kexec-tool will collect the iomem reserved info
and use it in second kernel, which causes error message generated a second time.

At the same time, we should free the reserved memblock in an aligned manner because
the initrd reserves the memblock in an aligned manner in arm64_memblock_init().
Otherwise there are some fragments in memblock_reserved regions. e.g.:
/sys/kernel/debug/memblock # cat reserved
0: 0x0000000080080000..0x00000000817fafff
1: 0x0000000083400000..0x0000000083ffffff
2: 0x0000000090000000..0x000000009000407f
3: 0x00000000b0000000..0x00000000b000003f
4: 0x00000000b26184ea..0x00000000b2618fff
The fragments like the ranges from b0000000 to b000003f and from b26184ea to b2618fff
should be freed.

Signed-off-by: Junhua Huang <huang.junhua@xxxxxxxxxx>
arch/arm64/mm/init.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index d2adffb81b5d..14ba8113eab5 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -580,8 +580,16 @@ void free_initmem(void)
void __init free_initrd_mem(unsigned long start, unsigned long end)
+ struct resource *res = NULL;
free_reserved_area((void *)start, (void *)end, 0, "initrd");
- memblock_free(__virt_to_phys(start), end - start);
+ start = __virt_to_phys(start) & PAGE_MASK;
+ end = PAGE_ALIGN(__virt_to_phys(end));
+ memblock_free(start, end - start);
+ res = lookup_resource(&iomem_resource, memblock_start_of_DRAM());
+ if (res != NULL)
+ __release_region(res, start, end - start);