linux-kernel - Re: [PATCH AUTOSEL 4.4 4/8] sparc32: Limit memblock allocation to low memory

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Date:   Wed, 3 Mar 2021 09:21:28 +0100
From:   Andreas Larsson <andreas@...sler.com>
To:     Sasha Levin <sashal@...nel.org>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Cc:     Mike Rapoport <rppt@...ux.ibm.com>,
        "David S . Miller" <davem@...emloft.net>,
        sparclinux@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 4.4 4/8] sparc32: Limit memblock allocation to low
 memory

On 2021-03-02 12:59, Sasha Levin wrote:
> From: Andreas Larsson <andreas@...sler.com>
> 
> [ 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@...sler.com>
> Acked-by: Mike Rapoport <rppt@...ux.ibm.com>
> Signed-off-by: David S. Miller <davem@...emloft.net>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>   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 3b7092d9ea8f..4abe4bf08377 100644
> --- a/arch/sparc/mm/init_32.c
> +++ b/arch/sparc/mm/init_32.c
> @@ -240,6 +240,9 @@ 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 4.4, and will not compile, as the problem it
fixes was introduced in 4.19.

-- 
Andreas Larsson