Re: [PATCH AUTOSEL 4.14 06/13] sparc32: Limit memblock allocation to low memory

[Andreas Larsson]

On 2021-03-02 12:58, Sasha Levin wrote:
> From: Andreas Larsson <andreas@xxxxxxxxxxx>
>
> [ Upstream commit bda166930c37604ffa93f2425426af6921ec575a ]
>
> Commit cca079ef8ac29a7c02192d2bad2ffe4c0c5ffdd0 changed sparc32 to use
> memblocks instead of bootmem, but also made high memory available via
> memblock allocation which does not work together with e.g. phys_to_virt
> and can lead to kernel panic.
>
> This changes back to only low memory being allocatable in the early
> stages, now using memblock allocation.
>
> Signed-off-by: Andreas Larsson <andreas@xxxxxxxxxxx>
> Acked-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
>   arch/sparc/mm/init_32.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/arch/sparc/mm/init_32.c b/arch/sparc/mm/init_32.c
> index 95fe4f081ba3..372a4f08ddf8 100644
> --- a/arch/sparc/mm/init_32.c
> +++ b/arch/sparc/mm/init_32.c
> @@ -230,6 +230,9 @@ unsigned long __init bootmem_init(unsigned long *pages_avail)
>   	reserve_bootmem((bootmap_pfn << PAGE_SHIFT), size, BOOTMEM_DEFAULT);
>   	*pages_avail -= PAGE_ALIGN(size) >> PAGE_SHIFT;
>   
> +	/* Only allow low memory to be allocated via memblock allocation */
> +	memblock_set_current_limit(max_low_pfn << PAGE_SHIFT);
> +
>   	return max_pfn;
>   }
>   

This is not needed for 4.14, and will not compile, as the problem it
fixes was introduced in 4.19.

--
Andreas Larsson