From: Michal Hocko <mhocko@kernel.org>
To: Andrew Morton <akpm@linux-foundation.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: [PATCH] mm: disallow early_pfn_to_nid on configurations which do not implement it
Date: Tue, 4 Jul 2017 09:58:03 +0200 [thread overview]
Message-ID: <20170704075803.15979-1-mhocko@kernel.org> (raw)
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.
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
Hi,
I have brought this up earlier [1] because I thought the deferred
initialization might be broken but then found out that this is not the
case right now. This is an attempt to prevent any subtly broken users in
future.
[1] http://lkml.kernel.org/r/20170630141847.GN22917@dhcp22.suse.cz
include/linux/mmzone.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 16532fa0bb64..fc14b8b3f6ce 100644
--- 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
--
2.11.0
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next reply other threads:[~2017-07-04 7:58 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-04 7:58 Michal Hocko [this message]
2017-07-04 9:28 ` [PATCH] mm: disallow early_pfn_to_nid on configurations which do not implement it Vlastimil Babka
2017-07-05 23:00 ` Andrew Morton
2017-07-06 6:50 ` Michal Hocko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170704075803.15979-1-mhocko@kernel.org \
--to=mhocko@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=js1304@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=mhocko@suse.com \
--cc=vbabka@suse.cz \
--cc=yang.shi@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).