linux-kernel - Re: [PATCH V2 2/2] mm/memblock.c: check return value of memblock_reserve() in memblock_virt_alloc

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Date:   Mon, 19 Dec 2016 16:21:57 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Wei Yang <richard.weiyang@...il.com>
Cc:     trivial@...nel.org, akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 2/2] mm/memblock.c: check return value of
 memblock_reserve() in memblock_virt_alloc_internal()

On Sun 18-12-16 14:47:50, Wei Yang wrote:
> memblock_reserve() may fail in case there is not enough regions.

Have you seen this happenning in the real setups or this is a by-review
driven change?
[...]
>  again:
>  	alloc = memblock_find_in_range_node(size, align, min_addr, max_addr,
>  					    nid, flags);
> -	if (alloc)
> +	if (alloc && !memblock_reserve(alloc, size))
>  		goto done;
>  
>  	if (nid != NUMA_NO_NODE) {
>  		alloc = memblock_find_in_range_node(size, align, min_addr,
>  						    max_addr, NUMA_NO_NODE,
>  						    flags);
> -		if (alloc)
> +		if (alloc && !memblock_reserve(alloc, size))
>  			goto done;
>  	}

This doesn't look right. You can end up leaking the first allocated
range.

>  
> @@ -1303,7 +1302,6 @@ static void * __init memblock_virt_alloc_internal(
>  
>  	return NULL;
>  done:
> -	memblock_reserve(alloc, size);
>  	ptr = phys_to_virt(alloc);
>  	memset(ptr, 0, size);


>  
> -- 
> 2.5.0
> 
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-- 
Michal Hocko
SUSE Labs