[PATCH] arm64:free_initrd_mem should also free the memblock

Hi

The reason that a want merge this patch is that
It confuse me when I debug memory issue by 
/sys/kernel/debug/memblock/reserved  debug file,
It show lots of un-correct reserved memory.
In fact, I also send a patch to cma driver part
For this issue too:
http://ozlabs.org/~akpm/mmots/broken-out/free-the-reserved-memblock-when-free-cma-pages.patch

I want to remove these un-correct memblock parts as much as possible,
so that I can see more correct info from /sys/kernel/debug/memblock/reserved
debug file .

Thanks



-----Original Message-----

On Mon, Sep 15, 2014 at 07:40:23PM +0100, Russell King - ARM Linux wrote:

On Mon, Sep 15, 2014 at 07:33:34PM +0100, Will Deacon wrote:

quoted

On Fri, Sep 12, 2014 at 11:17:18AM +0100, Wang, Yalin wrote:

quoted

this patch fix the memblock statics for memblock in file 
/sys/kernel/debug/memblock/reserved
if we don't call memblock_free the initrd will still be marked as 
reserved, even they are freed.

Signed-off-by: Yalin Wang <redacted>
---
 arch/arm64/mm/init.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 

5472c24..34605c8 100644

--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -334,8 +334,10 @@ static int keep_initrd;
 
 void free_initrd_mem(unsigned long start, unsigned long end)  {
-	if (!keep_initrd)
+	if (!keep_initrd) {
 		free_reserved_area((void *)start, (void *)end, 0, "initrd");
+		memblock_free(__pa(start), end - start);
+	}

I don't think it makes any technical difference, but doing the 
memblock_free before the free_reserved_area makes more sense to me.

A better question is... should we even be doing this.  The memblock 
information is used as a method to bring up the kernel and provide 
early allocation.  Once the memory is handed over from memblock to the 
normal kernel page allocators, we no longer care what happens to 
memblock.

There is no need to free the initrd memory back into memblock.  In 
fact, seeing the initrd location in 
/sys/kernel/debug/memblock/reserved
can be useful debug information in itself.

That's a fair point. Yang: do you have a specific use-case in mind for this?

I wondered if it might interact with our pfn_valid implementation, which uses memblock_is_memory, however memblock_free only deals with the reserved regions, so I now I can't see why this change is required either.

Will