Re: [PATCH RFC v2 4/4] mm/mempolicy: add nodes_empty check in SYSC_migrate_pages

On Tue, 7 Nov 2017, Yisheng Xie wrote:

On 2017/11/6 23:29, Christopher Lameter wrote:

quoted

On Mon, 6 Nov 2017, Vlastimil Babka wrote:

quoted

I'm not sure what exactly is the EPERM intention. Should really the
capability of THIS process override the cpuset restriction of the TARGET
process? Maybe yes. Then, does "insufficient privilege (CAP_SYS_NICE) to

CAP_SYS_NICE never overrides cpuset restrictions. The cap can be used to
migrate pages that are *also* mapped by other processes (and thus move
pages of another process which may have different cpu set restrictions!).

So you means the specified nodes should be a subset of target cpu set, right?

The specified nodes need to be part of the *current* cpu set.

Migrate pages moves the pages of a single process there is no TARGET
process.

Thus thehe *target* nodes need to be a subset of the current cpu set.