2023-09-26 12:12:28

by Huacai Chen

Subject: [PATCH] LoongArch: numa: Fix high_memory calculation

high_memory is the virtual address of the 'highest physical address' in
the system. But __va(get_num_physpages() << PAGE_SHIFT) is not what we
want because there may be holes in the physical address space. On the
other hand, max_low_pfn is calculated from memblock_end_of_DRAM(), which
is exactly corresponding to the highest physical address, so use it for
high_memory calculation.

Cc: <[email protected]>
Signed-off-by: Chong Qiao <[email protected]>
Signed-off-by: Huacai Chen <[email protected]>
---
arch/loongarch/kernel/numa.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/loongarch/kernel/numa.c b/arch/loongarch/kernel/numa.c
index c7d33c489e04..6e65ff12d5c7 100644
--- a/arch/loongarch/kernel/numa.c
+++ b/arch/loongarch/kernel/numa.c
@@ -436,7 +436,7 @@ void __init paging_init(void)

void __init mem_init(void)
{
- high_memory = (void *) __va(get_num_physpages() << PAGE_SHIFT);
+ high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
memblock_free_all();
}

--
2.39.3

2023-09-27 00:26:39

by WANG Xuerui

Subject: Re: [PATCH] LoongArch: numa: Fix high_memory calculation

On 9/26/23 20:10, Huacai Chen wrote:
> high_memory is the virtual address of the 'highest physical address' in
> the system. But __va(get_num_physpages() << PAGE_SHIFT) is not what we
> want because there may be holes in the physical address space. On the
> other hand, max_low_pfn is calculated from memblock_end_of_DRAM(), which
> is exactly corresponding to the highest physical address, so use it for
> high_memory calculation.
>
> Cc: <[email protected]>
Which commit is this patch intended to amend? A "Fixes:" tag may be
helpful for stable backporting.
> Signed-off-by: Chong Qiao <[email protected]>
> Signed-off-by: Huacai Chen <[email protected]>
> ---
> arch/loongarch/kernel/numa.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/loongarch/kernel/numa.c b/arch/loongarch/kernel/numa.c
> index c7d33c489e04..6e65ff12d5c7 100644
> --- a/arch/loongarch/kernel/numa.c
> +++ b/arch/loongarch/kernel/numa.c
> @@ -436,7 +436,7 @@ void __init paging_init(void)
>
> void __init mem_init(void)
> {
> - high_memory = (void *) __va(get_num_physpages() << PAGE_SHIFT);
> + high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
> memblock_free_all();
> }
>

--
WANG "xen0n" Xuerui

Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/

2023-09-27 03:09:03

by Huacai Chen

Subject: Re: [PATCH] LoongArch: numa: Fix high_memory calculation

On Tue, Sep 26, 2023 at 11:26 PM WANG Xuerui <[email protected]> wrote:
>
> On 9/26/23 20:10, Huacai Chen wrote:
> > high_memory is the virtual address of the 'highest physical address' in
> > the system. But __va(get_num_physpages() << PAGE_SHIFT) is not what we
> > want because there may be holes in the physical address space. On the
> > other hand, max_low_pfn is calculated from memblock_end_of_DRAM(), which
> > is exactly corresponding to the highest physical address, so use it for
> > high_memory calculation.
> >
> > Cc: <[email protected]>
> Which commit is this patch intended to amend? A "Fixes:" tag may be
> helpful for stable backporting.
OK, I will add a Fixes: tag.

Huacai

> > Signed-off-by: Chong Qiao <[email protected]>
> > Signed-off-by: Huacai Chen <[email protected]>
> > ---
> > arch/loongarch/kernel/numa.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/loongarch/kernel/numa.c b/arch/loongarch/kernel/numa.c
> > index c7d33c489e04..6e65ff12d5c7 100644
> > --- a/arch/loongarch/kernel/numa.c
> > +++ b/arch/loongarch/kernel/numa.c
> > @@ -436,7 +436,7 @@ void __init paging_init(void)
> >
> > void __init mem_init(void)
> > {
> > - high_memory = (void *) __va(get_num_physpages() << PAGE_SHIFT);
> > + high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
> > memblock_free_all();
> > }
> >
>
> --
> WANG "xen0n" Xuerui
>
> Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/
>