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Message-ID: <20230802112525.564928240@infradead.org>
Date: Wed, 02 Aug 2023 13:24:59 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: yury.norov@...il.com, andriy.shevchenko@...ux.intel.com,
linux@...musvillemoes.dk
Cc: peterz@...radead.org, Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
tglx@...utronix.de, rppt@...nel.org
Subject: [PATCH 1/2] mm: Mark nr_node_ids __ro_after_init
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) <peterz@...radead.org>
---
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);
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