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

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Message-Id: <1562063693-1541-1-git-send-email-wang.yi59@zte.com.cn>
Date:   Tue, 2 Jul 2019 18:34:53 +0800
From:   Yi Wang <wang.yi59@....com.cn>
To:     catalin.marinas@....com
Cc:     will.deacon@....com, akpm@...ux-foundation.org,
        rppt@...ux.vnet.ibm.com, f.fainelli@...il.com, logang@...tatee.com,
        robin.murphy@....com, ghackmann@...roid.com, hannes@...xchg.org,
        david@...hat.com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, xue.zhihong@....com.cn,
        wang.yi59@....com.cn, jiang.xuexin@....com.cn,
        Junhua Huang <huang.junhua@....com.cn>
Subject: [PATCH] remove the initrd resource in /proc/iomem  as the initrd has freed the reserved memblock.

From: Junhua Huang <huang.junhua@....com.cn>

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@....com.cn>
---
 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)
 #ifdef CONFIG_BLK_DEV_INITRD
 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);
+
 }
 #endif

-- 
2.15.2