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

From: Borislav Petkov
Date: Mon Jun 26 2017 - 11:32:19 EST


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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