Re: [PATCH V2 1/3] x86/numa_emulation: fix potential memory leak

[Borislav Petkov]

On Tue, May 02, 2017 at 09:04:51PM +0800, Wei Yang wrote:
> numa_emulation() needs to allocate a space for phys_dist[] temporarily,

s/a //

> while current code may miss to release this when dfl_phys_nid ==
> NUMA_NO_NODE.

And when is "dfl_phys_nid == NUMA_NO_NODE"? What does it mean actually?

> It is observed in code review instead of in a real case.
> This patch fixes this by re-order the code path.
> 
> Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
> Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
> ---
>  arch/x86/mm/numa_emulation.c | 36 ++++++++++++++++++------------------
>  1 file changed, 18 insertions(+), 18 deletions(-)
> 
> diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
> index a8f90ce3dedf..eb017c816de6 100644
> --- a/arch/x86/mm/numa_emulation.c
> +++ b/arch/x86/mm/numa_emulation.c
> @@ -353,6 +353,24 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
>  		goto no_emu;
>  	}
>  
> +	/*
> +	 * Determine the max emulated nid and the default phys nid to use
> +	 * for unmapped nodes.
> +	 */
> +	max_emu_nid = 0;
> +	dfl_phys_nid = NUMA_NO_NODE;
> +	for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++) {
> +		if (emu_nid_to_phys[i] != NUMA_NO_NODE) {
> +			max_emu_nid = i;
> +			if (dfl_phys_nid == NUMA_NO_NODE)
> +				dfl_phys_nid = emu_nid_to_phys[i];
> +		}
> +	}
> +	if (dfl_phys_nid == NUMA_NO_NODE) {
> +		pr_warn("NUMA: Warning: can't determine default physical node, disabling emulation\n");
> +		goto no_emu;
> +	}
> +

Well, that function numa_emulation() does a looot of things and could
very well be split into subfunctions, which should make the whole path
more readable.

And this chunk you're moving is kinda begging to be a separate
function...

-- 
Regards/Gruss,
    Boris.

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