Re: [PATCH] [mempolicy] remove unnecessary is_valid_nodemask()

[Zhihui Zhang]

The filtering occurs in mpol_set_nodemask(), it reads like this:

                if (pol->flags & MPOL_F_RELATIVE_NODES)
                        mpol_relative_nodemask(&nsc->mask2, nodes,&nsc->mask1);
                else
                        nodes_and(nsc->mask2, *nodes, nsc->mask1);

so mask2 is based on mask1. mask2 is only used when nodes is not NULL
later. so we don't care the
case of (pol->mode == MPOL_PREFERRED && nodes_empty(*nodes)).

-Zhihui

On Mon, Nov 17, 2014 at 6:08 PM, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Sat, 15 Nov 2014 21:49:57 -0500 Zhihui Zhang <zzhsuny@xxxxxxxxx> wrote:
>
>> When nodes is true, nsc->mask2 has already been filtered by nsc->mask1, which has
>> already factored in node_states[N_MEMORY].
>>
>
> Please be more specific.  Where does that filtering occur?
>
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