Re: [v3 PATCH 1/3] mm/mempolicy: cleanup nodemask intersection check for oom

[Feng Tang]

On Tue, Jun 01, 2021 at 10:19:25AM +0200, Michal Hocko wrote:
> On Mon 31-05-21 22:05:54, Feng Tang wrote:
> > mempolicy_nodemask_intersects() is used in oom case to check if a
> > task may have memory allocated on some memory nodes.
> > 
> > As it's only used by OOM check, rename it to mempolicy_in_oom_domain()
> > to reduce confusion.
> > 
> > As only for 'bind' policy, the nodemask is a force requirement for
> > from where to allocate memory, only do the intesection check for it,
> > and return true for all other policies.
> 
> I would slightly rephrase the above to
> "
> mempolicy_nodemask_intersects seem to be a general purpose mempolicy
> function. In fact it is partially tailored for the OOM purpose instead.
> The oom proper is the only existing user so rename the function to make
> that purpose explicit.
> 
> While at it drop the MPOL_INTERLEAVE as those allocations never has a
> nodemask defined (see alloc_page_interleave) so this is a dead code
> and a confusing one because MPOL_INTERLEAVE is a hint rather than a hard
> requirement so it shouldn't be considered during the OOM.
> 
> The final code can be reduced to a check for MPOL_BIND which is the only
> memory policy that is a hard requirement and thus relevant to a
> constrained OOM logic.
> "

This is much clearer, thanks!

Will change this and the descrition in over-letter.

> > Suggested-by: Michal Hocko <mhocko@xxxxxxxx>
> > Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx>
> 
> To the change itself
> Acked-by: Michal Hocko <mhocko@xxxxxxxx>

Thanks!

- Feng