Re: [PATCH 2/3] mm,thp,shm: limit gfp mask to no more than specified

[Rik van Riel]

On Fri, 2020-11-27 at 08:52 +0100, Michal Hocko wrote:
> On Thu 26-11-20 13:04:14, Rik van Riel wrote:
> > 
> > I would be more than happy to implement things differently,
> > but I am not sure what alternative you are suggesting.
> 
> Simply do not alter gfp flags? Or warn in some cases of a serious
> mismatch.
> E.g. GFP_ZONEMASK mismatch because there are already GFP_KERNEL users
> of
> shmem.

Not altering the gfp flags is not really an option,
because that would leads to attempting to allocate THPs
with GFP_HIGHUSER, which is what is used to allocate
regular tmpfs pages.

If the THP configuration in sysfs says we should
not
be doing compaction/reclaim from THP allocations, we
should obey that configuration setting, and use a 
gfp_flags that results in no compaction/reclaim being done.

-- 
All Rights Reversed.

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