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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1690988333; bh=B7PJRVoGZn23p+r9ALJfQkaFSMSdvGQQe71SQW5MouE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mFSg7MtuMOK79DRkwdkU1CdTUuLXgUd5UXk21tLHtAp2+//+xfRPaGBeq6q+c+8V5 PchdJkSbL89oPhlZ1LqTQ0RluHHPPJ4dmC7ExFVW4BjAtW59549gjAO8Liq+A2AFzr KBqjk3Y/yN2afvObEQkvHOn45mc2ClgEoM++82Q/FFKOXS4pKl7dhMtfgUPhTBG1NX 5U2Ko34ctP+R5STcvGTLg/ndWCFbaanRDFCx6/PP8XT+xpIwuD7aFB499wHKo41APy zmvXRuBkfcxK2E3CnSySGbgYgjB5ml5HhmYZtRiZLlst16MDSNVNyXN563YsQfy9B1 kJ6istljo0Njw== Date: Wed, 2 Aug 2023 17:58:09 +0300 From: Mike Rapoport To: Peter Zijlstra Cc: yury.norov@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk, Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, tglx@linutronix.de Subject: Re: [PATCH 1/2] mm: Mark nr_node_ids __ro_after_init Message-ID: <20230802145809.GE2607694@kernel.org> References: <20230802112458.230221601@infradead.org> <20230802112525.564928240@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230802112525.564928240@infradead.org> X-Rspamd-Queue-Id: C20514000C X-Rspam-User: X-Stat-Signature: d9rntu7o44r3paifqqy5jwgbcjobhhny X-Rspamd-Server: rspam03 X-HE-Tag: 1690988335-130362 X-HE-Meta: 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 bQFf0hon 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 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: On Wed, Aug 02, 2023 at 01:24:59PM +0200, Peter Zijlstra wrote: > 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); > > -- Sincerely yours, Mike.