From: Andrew Morton <akpm@linux-foundation.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>, Joonsoo Kim <js1304@gmail.com>,
Yang Shi <yang.shi@linaro.org>, Mel Gorman <mgorman@suse.de>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH] mm: disallow early_pfn_to_nid on configurations which do not implement it
Date: Wed, 5 Jul 2017 16:00:55 -0700 [thread overview]
Message-ID: <20170705160055.013fa5ff34bdf1f6efa4e6ce@linux-foundation.org> (raw)
In-Reply-To: <20170704075803.15979-1-mhocko@kernel.org>
On Tue, 4 Jul 2017 09:58:03 +0200 Michal Hocko <mhocko@kernel.org> wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> early_pfn_to_nid will return node 0 if both HAVE_ARCH_EARLY_PFN_TO_NID
> and HAVE_MEMBLOCK_NODE_MAP are disabled. It seems we are safe now
> because all architectures which support NUMA define one of them (with an
> exception of alpha which however has CONFIG_NUMA marked as broken) so
> this works as expected. It can get silently and subtly broken too
> easily, though. Make sure we fail the compilation if NUMA is enabled and
> there is no proper implementation for this function. If that ever
> happens we know that either the specific configuration is invalid
> and the fix should either disable NUMA or enable one of the above
> configs.
>
> ...
>
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -1055,6 +1055,7 @@ static inline struct zoneref *first_zones_zonelist(struct zonelist *zonelist,
> !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
> static inline unsigned long early_pfn_to_nid(unsigned long pfn)
> {
> + BUILD_BUG_ON(IS_ENABLED(CONFIG_NUMA));
> return 0;
> }
> #endif
Wouldn't this be more conventional?
--- a/include/linux/mmzone.h~a
+++ a/include/linux/mmzone.h
@@ -1052,7 +1052,8 @@ static inline struct zoneref *first_zone
#endif
#if !defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID) && \
- !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
+ !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP) && \
+ !defined(CONFIG_NUMA)
static inline unsigned long early_pfn_to_nid(unsigned long pfn)
{
return 0;
_
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next prev parent reply other threads:[~2017-07-05 23:00 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-04 7:58 [PATCH] mm: disallow early_pfn_to_nid on configurations which do not implement it Michal Hocko
2017-07-04 9:28 ` Vlastimil Babka
2017-07-05 23:00 ` Andrew Morton [this message]
2017-07-06 6:50 ` Michal Hocko
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