Re: [PATCH v7 3/5] mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY

On Mon 09-08-21 20:37:47, Feng Tang wrote:

On Mon, Aug 09, 2021 at 10:41:40AM +0200, Michal Hocko wrote:
[snip]

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From fc30718c40f02ba5ea73456af49173e66b5032c1 Mon Sep 17 00:00:00 2001

From: Ben Widawsky <redacted>
Date: Thu, 5 Aug 2021 23:01:11 -0400
Subject: [PATCH] mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY

Implement the missing huge page allocation functionality while obeying the
preferred node semantics.  This is similar to the implementation for
general page allocation, as it uses a fallback mechanism to try multiple
preferred nodes first, and then all other nodes. 

To avoid adding too many "#ifdef CONFIG_NUMA" check, add a helper function
in mempolicy.h to check whether a mempolicy is MPOL_PREFERRED_MANY.

[akpm: fix compling issue when merging with other hugetlb patch]
[Thanks to 0day bot for catching the !CONFIG_NUMA compiling issue]
[Michal Hocko: suggest to remove the #ifdef CONFIG_NUMA check]
Link: https://lore.kernel.org/r/20200630212517.308045-12-ben.widawsky@intel.com (local)
Link: https://lkml.kernel.org/r/1627970362-61305-4-git-send-email-feng.tang@intel.com
Suggested-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Ben Widawsky <redacted>
Co-developed-by: Feng Tang <redacted>
Signed-off-by: Feng Tang <redacted>

Yeah. This looks much better. Thanks!
Acked-by: Michal Hocko <mhocko@suse.com>

Thank you!

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Do you think you can provide same helpers for other policies as well?
Maybe we can get rid of some other ifdefery as well.

Sure. I can make separate patch(es) for that.

And you mean helper like mpol_is_bind/default/local/preferred? 

I just run 'git-grep MPOL', and for places using "mode == MPOL_XXX",
mostly they are in mempolicy.[ch], the only another place is in
shmem.c, do we need to create all the helpers for it and the
potential future users? 

I would just go with those instances which need to ifdef for NUMA.
Thanks!
-- 
Michal Hocko
SUSE Labs