Re: [PATCH] mm/hugetlb: Get rid of NODEMASK_ALLOC

From: Andrew Morton
Date: Tue Apr 02 2019 - 16:01:58 EST

On Tue, 2 Apr 2019 15:34:15 +0200 Oscar Salvador <osalvador@xxxxxxx> wrote:

> NODEMASK_ALLOC is used to allocate a nodemask bitmap, ant it does it by
> first determining whether it should be allocated in the stack or dinamically
> depending on NODES_SHIFT.
> Right now, it goes the dynamic path whenever the nodemask_t is above 32
> bytes.
> Although we could bump it to a reasonable value, the largest a nodemask_t
> can get is 128 bytes, so since __nr_hugepages_store_common is called from
> a rather shore stack we can just get rid of the NODEMASK_ALLOC call here.
> This reduces some code churn and complexity.

It took a bit of sleuthing to figure out that this patch applies to
Mike's "hugetlbfs: fix potential over/underflow setting node specific
nr_hugepages". Should they be folded together? I'm thinking not.

(Also, should "hugetlbfs: fix potential over/underflow setting node
specific nr_hugepages" have been -stableified? I also think not, but I
bet it happens anyway).