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* [PATCH v3] RISC-V: Remove any memblock representing unusable memory area
@ 2020-10-01 19:05 Atish Patra
  2020-10-02 10:12 ` Anup Patel
  2020-10-04 23:22 ` Palmer Dabbelt
  0 siblings, 2 replies; 3+ messages in thread
From: Atish Patra @ 2020-10-01 19:05 UTC (permalink / raw)
  To: linux-kernel
  Cc: Albert Ou, Anup Patel, Mike Rapoport, Atish Patra,
	Palmer Dabbelt, Zong Li, Paul Walmsley, linux-riscv

RISC-V limits the physical memory size by -PAGE_OFFSET. Any memory beyond
that size from DRAM start is unusable. Just remove any memblock pointing
to those memory region without worrying about computing the maximum size.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>

---
Changes from v2->v3
Updated comment as per Mike's suggestion.
---
 arch/riscv/mm/init.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index ca03762a3733..564e0be677b7 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -146,8 +146,6 @@ static phys_addr_t dtb_early_pa __initdata;
 void __init setup_bootmem(void)
 {
 	struct memblock_region *reg;
-	phys_addr_t mem_size = 0;
-	phys_addr_t total_mem = 0;
 	phys_addr_t mem_start, end = 0;
 	phys_addr_t vmlinux_end = __pa_symbol(&_end);
 	phys_addr_t vmlinux_start = __pa_symbol(&_start);
@@ -155,21 +153,18 @@ void __init setup_bootmem(void)
 	/* Find the memory region containing the kernel */
 	for_each_memblock(memory, reg) {
 		end = reg->base + reg->size;
-		if (!total_mem)
+		if (!mem_start)
 			mem_start = reg->base;
 		if (reg->base <= vmlinux_start && vmlinux_end <= end)
 			BUG_ON(reg->size == 0);
-		total_mem = total_mem + reg->size;
 	}
 
 	/*
-	 * Remove memblock from the end of usable area to the
-	 * end of region
+	 * The maximal physical memory size is -PAGE_OFFSET.
+	 * Make sure that any memory beyond mem_start + (-PAGE_OFFSET) is removed
+	 * as it is unusable by kernel.
 	 */
-	mem_size = min(total_mem, (phys_addr_t)-PAGE_OFFSET);
-	if (mem_start + mem_size < end)
-		memblock_remove(mem_start + mem_size,
-				end - mem_start - mem_size);
+	memblock_enforce_memory_limit(mem_start - PAGE_OFFSET);
 
 	/* Reserve from the start of the kernel to the end of the kernel */
 	memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);
-- 
2.25.1


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^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH v3] RISC-V: Remove any memblock representing unusable memory area
  2020-10-01 19:05 [PATCH v3] RISC-V: Remove any memblock representing unusable memory area Atish Patra
@ 2020-10-02 10:12 ` Anup Patel
  2020-10-04 23:22 ` Palmer Dabbelt
  1 sibling, 0 replies; 3+ messages in thread
From: Anup Patel @ 2020-10-02 10:12 UTC (permalink / raw)
  To: Atish Patra
  Cc: Albert Ou, Anup Patel, linux-kernel@vger.kernel.org List,
	Mike Rapoport, Palmer Dabbelt, Zong Li, Paul Walmsley,
	linux-riscv

On Fri, Oct 2, 2020 at 12:36 AM Atish Patra <atish.patra@wdc.com> wrote:
>
> RISC-V limits the physical memory size by -PAGE_OFFSET. Any memory beyond
> that size from DRAM start is unusable. Just remove any memblock pointing
> to those memory region without worrying about computing the maximum size.
>
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
>
> ---
> Changes from v2->v3
> Updated comment as per Mike's suggestion.
> ---
>  arch/riscv/mm/init.c | 15 +++++----------
>  1 file changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index ca03762a3733..564e0be677b7 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -146,8 +146,6 @@ static phys_addr_t dtb_early_pa __initdata;
>  void __init setup_bootmem(void)
>  {
>         struct memblock_region *reg;
> -       phys_addr_t mem_size = 0;
> -       phys_addr_t total_mem = 0;
>         phys_addr_t mem_start, end = 0;
>         phys_addr_t vmlinux_end = __pa_symbol(&_end);
>         phys_addr_t vmlinux_start = __pa_symbol(&_start);
> @@ -155,21 +153,18 @@ void __init setup_bootmem(void)
>         /* Find the memory region containing the kernel */
>         for_each_memblock(memory, reg) {
>                 end = reg->base + reg->size;
> -               if (!total_mem)
> +               if (!mem_start)
>                         mem_start = reg->base;
>                 if (reg->base <= vmlinux_start && vmlinux_end <= end)
>                         BUG_ON(reg->size == 0);
> -               total_mem = total_mem + reg->size;
>         }
>
>         /*
> -        * Remove memblock from the end of usable area to the
> -        * end of region
> +        * The maximal physical memory size is -PAGE_OFFSET.
> +        * Make sure that any memory beyond mem_start + (-PAGE_OFFSET) is removed
> +        * as it is unusable by kernel.
>          */
> -       mem_size = min(total_mem, (phys_addr_t)-PAGE_OFFSET);
> -       if (mem_start + mem_size < end)
> -               memblock_remove(mem_start + mem_size,
> -                               end - mem_start - mem_size);
> +       memblock_enforce_memory_limit(mem_start - PAGE_OFFSET);
>
>         /* Reserve from the start of the kernel to the end of the kernel */
>         memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);
> --
> 2.25.1
>

Looks good to me.

Reviewed-by: Anup Patel <anup@brainfault.org>

Regards,
Anup

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^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH v3] RISC-V: Remove any memblock representing unusable memory area
  2020-10-01 19:05 [PATCH v3] RISC-V: Remove any memblock representing unusable memory area Atish Patra
  2020-10-02 10:12 ` Anup Patel
@ 2020-10-04 23:22 ` Palmer Dabbelt
  1 sibling, 0 replies; 3+ messages in thread
From: Palmer Dabbelt @ 2020-10-04 23:22 UTC (permalink / raw)
  To: Atish Patra
  Cc: aou, Anup Patel, linux-kernel, rppt, Atish Patra, zong.li,
	Paul Walmsley, linux-riscv

On Thu, 01 Oct 2020 12:05:57 PDT (-0700), Atish Patra wrote:
> RISC-V limits the physical memory size by -PAGE_OFFSET. Any memory beyond
> that size from DRAM start is unusable. Just remove any memblock pointing
> to those memory region without worrying about computing the maximum size.
>
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
>
> ---
> Changes from v2->v3
> Updated comment as per Mike's suggestion.
> ---
>  arch/riscv/mm/init.c | 15 +++++----------
>  1 file changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index ca03762a3733..564e0be677b7 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -146,8 +146,6 @@ static phys_addr_t dtb_early_pa __initdata;
>  void __init setup_bootmem(void)
>  {
>  	struct memblock_region *reg;
> -	phys_addr_t mem_size = 0;
> -	phys_addr_t total_mem = 0;
>  	phys_addr_t mem_start, end = 0;
>  	phys_addr_t vmlinux_end = __pa_symbol(&_end);
>  	phys_addr_t vmlinux_start = __pa_symbol(&_start);
> @@ -155,21 +153,18 @@ void __init setup_bootmem(void)
>  	/* Find the memory region containing the kernel */
>  	for_each_memblock(memory, reg) {
>  		end = reg->base + reg->size;
> -		if (!total_mem)
> +		if (!mem_start)
>  			mem_start = reg->base;
>  		if (reg->base <= vmlinux_start && vmlinux_end <= end)
>  			BUG_ON(reg->size == 0);
> -		total_mem = total_mem + reg->size;
>  	}
>
>  	/*
> -	 * Remove memblock from the end of usable area to the
> -	 * end of region
> +	 * The maximal physical memory size is -PAGE_OFFSET.
> +	 * Make sure that any memory beyond mem_start + (-PAGE_OFFSET) is removed
> +	 * as it is unusable by kernel.
>  	 */
> -	mem_size = min(total_mem, (phys_addr_t)-PAGE_OFFSET);
> -	if (mem_start + mem_size < end)
> -		memblock_remove(mem_start + mem_size,
> -				end - mem_start - mem_size);
> +	memblock_enforce_memory_limit(mem_start - PAGE_OFFSET);
>
>  	/* Reserve from the start of the kernel to the end of the kernel */
>  	memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);

Thanks, this is on for-next.

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^ permalink raw reply	[flat|nested] 3+ messages in thread

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2020-10-01 19:05 [PATCH v3] RISC-V: Remove any memblock representing unusable memory area Atish Patra
2020-10-02 10:12 ` Anup Patel
2020-10-04 23:22 ` Palmer Dabbelt

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