Re: [External] Re: [RFC] mm: add new syscall pidfd_set_mempolicy()

Zhongkun He
2022-10-13T12:51:13Z

>> Hi Michal
>>
>> Could we try to change the MPOL_F_SHARED flag to MPOL_F_STATIC to
>> mark static mempolicy which cannot be freed, and mpol_needs_cond_ref
>> can use MPOL_F_STATIC to avoid freeing the static mempolicy.
>
> Wouldn't it make more sense to get rid of a different treatment and
> treat all memory policies the same way?

I found a case, not sure if it makes sense. If there is no policy
in task->mempolicy, the use of atomic_{inc,dec} can be skiped
according to MPOL_F_STATIC. Atomic_{inc,dec} in hot path may reduces
performance.

Thanks.