[PATCH v2] of/fdt: memblock_reserve /memreserve/ regions in the case of partial overlap

[PATCH v2] of/fdt: memblock_reserve /memreserve/ regions in the case of partial overlap

[Ian Campbell]

memblock_is_region_reserved() returns true in the case of a partial
overlap, meaning that the current code fails to reserve the
non-overlapping portion.

This call was introduced as part of d1552ce449eb "of/fdt: move
memreserve and dtb memory reservations into core" which went into
v3.16.

I observed this causing a Midway system with a buggy fdt (the header
declares itself to be larger than it really is) failing to boot
because the over-inflated size of the fdt was causing it to seem to
run into the swapper_pg_dir region, meaning the DT wasn't reserved.
The symptoms were failing to find an disks or network and failing to
boot.

However given the ambiguity of whether things like the initrd are
covered by /memreserve/ and similar I think it is best to also
register the region rather than just ignoring it.

Since memblock_reserve() handles overlaps just fine lets just warn and
carry on.

Signed-off-by: Ian Campbell <ian.campbell-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org>
Cc: Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Cc: Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org # v3.16+
---
v2: Tag for stable v3.16+
    Just drop the test, no need to log.
---
 drivers/of/fdt.c |    2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 30e97bc..d134710 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -964,8 +964,6 @@ void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
 int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base,
 					phys_addr_t size, bool nomap)
 {
-	if (memblock_is_region_reserved(base, size))
-		return -EBUSY;
 	if (nomap)
 		return memblock_remove(base, size);
 	return memblock_reserve(base, size);
-- 
1.7.10.4

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Re: [PATCH v2] of/fdt: memblock_reserve /memreserve/ regions in the case of partial overlap

[Grant Likely]

On Tue, 25 Nov 2014 15:05:13 +0000
, Ian Campbell <ian.campbell-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org>
 wrote:
> memblock_is_region_reserved() returns true in the case of a partial
> overlap, meaning that the current code fails to reserve the
> non-overlapping portion.
> 
> This call was introduced as part of d1552ce449eb "of/fdt: move
> memreserve and dtb memory reservations into core" which went into
> v3.16.
> 
> I observed this causing a Midway system with a buggy fdt (the header
> declares itself to be larger than it really is) failing to boot
> because the over-inflated size of the fdt was causing it to seem to
> run into the swapper_pg_dir region, meaning the DT wasn't reserved.
> The symptoms were failing to find an disks or network and failing to
> boot.
> 
> However given the ambiguity of whether things like the initrd are
> covered by /memreserve/ and similar I think it is best to also
> register the region rather than just ignoring it.
> 
> Since memblock_reserve() handles overlaps just fine lets just warn and
> carry on.
> 
> Signed-off-by: Ian Campbell <ian.campbell-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org>
> Cc: Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> Cc: Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org # v3.16+

Applied, thanks.

g.

> ---
> v2: Tag for stable v3.16+
>     Just drop the test, no need to log.
> ---
>  drivers/of/fdt.c |    2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 30e97bc..d134710 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -964,8 +964,6 @@ void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
>  int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base,
>  					phys_addr_t size, bool nomap)
>  {
> -	if (memblock_is_region_reserved(base, size))
> -		return -EBUSY;
>  	if (nomap)
>  		return memblock_remove(base, size);
>  	return memblock_reserve(base, size);
> -- 
> 1.7.10.4
> 

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