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Wed, 2 Aug 2023 13:25:34 +0200 (CEST) Message-ID: <20230802112525.564928240@infradead.org> User-Agent: quilt/0.66 Date: Wed, 02 Aug 2023 13:24:59 +0200 From: Peter Zijlstra To: yury.norov@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk Cc: peterz@infradead.org, Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, tglx@linutronix.de, rppt@kernel.org Subject: [PATCH 1/2] mm: Mark nr_node_ids __ro_after_init References: <20230802112458.230221601@infradead.org> MIME-Version: 1.0 X-Rspamd-Queue-Id: 1C750C000C X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: d3nndeos78rkcgfwha5ousonu6ahcuuu X-HE-Tag: 1690975540-262610 X-HE-Meta: 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 wYlD743/ imwGhHMWFC9kzwb1tu7Lih7ZHPkQ2KtyYMkrm7TOn1KQ9oTncLutN0K42Ylf7JYLZOT9DBafAyiEDkYWJx2aQrwePmOsv9SfFhtpXtmbflsEO5GQewI7LshPGyHTpJJn0ui+1tQsj1SY5ruA9MBKSuVcKMuB4a3FQye++m5PwI+hk/OTYxfLouIx86J32hKXH/+n7mBzwUVM34NmoBvgwtlTni4QcF7CCi94H8A60o1GHLnaHryozCkwJegsjacpY66ijTb61sMdtW4YGS9YFdGMhEL3bTBqSKJOYGLQhXPyMdQBClFDKisOSe3b852E1G8wxQyL+k497FTTsN9o42CJztyaycLX7A0P1DlZ61g+boSunV7mJ0Nfa6IsMLNMUJ0Mff6ZLAmSiE78UGYqddhC05wqEKDpbs5on X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Just like nr_cpu_ids, nr_node_ids covers the side of possible_map and is thus constant after init. Mark the variable __ro_after_init to both improve performance and enhance security, since the variable is exported. A module writing to it would be 'unfortunate'. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Mike Rapoport (IBM) --- mm/page_alloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -305,7 +305,7 @@ int movable_zone; EXPORT_SYMBOL(movable_zone); #if MAX_NUMNODES > 1 -unsigned int nr_node_ids __read_mostly = MAX_NUMNODES; +unsigned int nr_node_ids __ro_after_init = MAX_NUMNODES; unsigned int nr_online_nodes __read_mostly = 1; EXPORT_SYMBOL(nr_node_ids); EXPORT_SYMBOL(nr_online_nodes);