linux-kernel - Re: [PATCH] memblock: check memory total

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Date:   Tue, 28 Sep 2021 09:37:55 -0700
From:   Mike Rapoport <rppt@...nel.org>
To:     "Peng Fan (OSS)" <peng.fan@....nxp.com>
Cc:     akpm@...ux-foundation.org, david@...hat.com,
        geert+renesas@...der.be, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Peng Fan <peng.fan@....com>
Subject: Re: [PATCH] memblock: check memory total_size

Hi,

On Tue, Sep 28, 2021 at 06:50:57PM +0800, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@....com>
> 
> mem=[X][G|M] is broken on NXP i.MX ARM64 platform, there is cases that
> even type.cnt is 1, but total_size is not 0 because regions are merged
> into 1. So only check 'cnt' is not enough, total_size also needs to be
> taked into consideration, othersize bootargs 'mem=[X][G|B]' not work
> anymore.

I believe this is issue is not specific to i.MX but rather this could
happen on any arm64 platform. Can you please update the changelog?
 
> Fixes: e888fa7bb882 ("memblock: Check memory add/cap ordering")
> Cc: Mike Rapoport <rppt@...nel.org>
> Cc: Geert Uytterhoeven <geert+renesas@...der.be>
> Cc: David Hildenbrand <david@...hat.com>
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
>  mm/memblock.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 184dcd2e5d99..ab67b82a9cce 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -1687,7 +1687,7 @@ void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size)
>  	if (!size)
>  		return;
>  
> -	if (memblock.memory.cnt <= 1) {
> +	if (memblock_memory->cnt <= 1 && !memblock_memory->total_size) {

The test for non-zero total size shold be sufficient here.

>  		pr_warn("%s: No memory registered yet\n", __func__);
>  		return;
>  	}
> -- 
> 2.30.0
> 

-- 
Sincerely yours,
Mike.