Re: [PATCH 05/10] mm, page_alloc: Remove unnecessary updating of GFP flags during normal operation

[Mel Gorman <mgorman@techsingularity.net>]

On Tue, Jul 28, 2015 at 03:36:05PM +0200, Vlastimil Babka wrote:
> >--- a/mm/page_alloc.c
> >+++ b/mm/page_alloc.c
> >@@ -124,7 +124,9 @@ unsigned long totalcma_pages __read_mostly;
> >  unsigned long dirty_balance_reserve __read_mostly;
> >
> >  int percpu_pagelist_fraction;
> >-gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
> >+
> >+gfp_t __gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
> >+struct static_key gfp_restricted_key __read_mostly = STATIC_KEY_INIT_TRUE;
> 
> ... and here it's combined with STATIC_KEY_INIT_TRUE. I've suspected
> that this is not allowed, which Peter confirmed on IRC.
> 

Thanks because I was not aware of hazards of that nature. I'll drop the
jump-label related patches from the series until the patches related to
the correct idiom are finalised. The micro-optimisations are not the
main point of this series and the savings are tiny.

-- 
Mel Gorman
SUSE Labs

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