[PATCH] [v4] ppc: force memory size to be a multiple of PAGE_SIZE

[PATCH] [v4] ppc: force memory size to be a multiple of PAGE_SIZE

[Hollis Blanchard]

Ensure that total memory size is page-aligned, because otherwise
mark_bootmem() gets upset.

This error case was triggered by using 64 KiB pages in the kernel while
arch/powerpc/boot/4xx.c arbitrarily reduced the amount of memory by 4096 (to
work around a chip bug that affects the last 256 bytes of physical memory).

Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
---
Changes from v3:
- No need to call lmb_enforce_memory_limit() with limit=lmb_phys_mem_size().

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -1160,6 +1160,8 @@ static inline void __init phyp_dump_rese
 
 void __init early_init_devtree(void *params)
 {
+	unsigned long limit;
+
 	DBG(" -> early_init_devtree(%p)\n", params);
 
 	/* Setup flat device-tree pointer */
@@ -1200,7 +1202,19 @@ void __init early_init_devtree(void *par
 	early_reserve_mem();
 	phyp_dump_reserve_mem();
 
-	lmb_enforce_memory_limit(memory_limit);
+	limit = memory_limit;
+	if (! limit) {
+		unsigned long memsize;
+
+		/* Ensure that total memory size is page-aligned, because
+		 * otherwise mark_bootmem() gets upset. */
+		lmb_analyze();
+		memsize = lmb_phys_mem_size();
+		if ((memsize & PAGE_MASK) != memsize)
+			limit = memsize & PAGE_MASK;
+	}
+	lmb_enforce_memory_limit(limit);
+
 	lmb_analyze();
 
 	DBG("Phys. mem: %lx\n", lmb_phys_mem_size());

Re: [PATCH] [v4] ppc: force memory size to be a multiple of PAGE_SIZE

[Hollis Blanchard]

On Wed, Nov 26, 2008 at 10:19 AM, Hollis Blanchard <hollisb@us.ibm.com> wrote:
> Ensure that total memory size is page-aligned, because otherwise
> mark_bootmem() gets upset.
>
> This error case was triggered by using 64 KiB pages in the kernel while
> arch/powerpc/boot/4xx.c arbitrarily reduced the amount of memory by 4096 (to
> work around a chip bug that affects the last 256 bytes of physical memory).
>
> Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
> ---
> Changes from v3:
> - No need to call lmb_enforce_memory_limit() with limit=lmb_phys_mem_size().
>
> diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
> --- a/arch/powerpc/kernel/prom.c
> +++ b/arch/powerpc/kernel/prom.c
> @@ -1160,6 +1160,8 @@ static inline void __init phyp_dump_rese
>
>  void __init early_init_devtree(void *params)
>  {
> +       unsigned long limit;
> +
>        DBG(" -> early_init_devtree(%p)\n", params);
>
>        /* Setup flat device-tree pointer */
> @@ -1200,7 +1202,19 @@ void __init early_init_devtree(void *par
>        early_reserve_mem();
>        phyp_dump_reserve_mem();
>
> -       lmb_enforce_memory_limit(memory_limit);
> +       limit = memory_limit;
> +       if (! limit) {
> +               unsigned long memsize;
> +
> +               /* Ensure that total memory size is page-aligned, because
> +                * otherwise mark_bootmem() gets upset. */
> +               lmb_analyze();
> +               memsize = lmb_phys_mem_size();
> +               if ((memsize & PAGE_MASK) != memsize)
> +                       limit = memsize & PAGE_MASK;
> +       }
> +       lmb_enforce_memory_limit(limit);
> +
>        lmb_analyze();
>
>        DBG("Phys. mem: %lx\n", lmb_phys_mem_size());

Paul or Ben: since there have been no further comments on this, would
you queue it up for 2.6.29? Thanks.

-Hollis