[PATCH V4 1/3] arm64/mm/hotplug: Register boot memory hot remove notifier earlier

From: Anshuman Khandual <anshuman.khandual@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: catalin.marinas@arm.com, will@kernel.org, gshan@redhat.com,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Steve Capper <steve.capper@arm.com>,
	Mark Brown <broonie@kernel.org>,
	linux-kernel@vger.kernel.org
Subject: [PATCH V4 1/3] arm64/mm/hotplug: Register boot memory hot remove notifier earlier
Date: Tue, 29 Sep 2020 19:24:45 +0530	[thread overview]
Message-ID: <1601387687-6077-2-git-send-email-anshuman.khandual@arm.com> (raw)
In-Reply-To: <1601387687-6077-1-git-send-email-anshuman.khandual@arm.com>

This moves memory notifier registration earlier in the boot process from
device_initcall() to early_initcall() which will help in guarding against
potential early boot memory offline requests. Even though there should not
be any actual offlinig requests till memory block devices are initialized
with memory_dev_init() but then generic init sequence might just change in
future. Hence an early registration for the memory event notifier would be
helpful. While here, just skip the registration if CONFIG_MEMORY_HOTREMOVE
is not enabled and also call out when memory notifier registration fails.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
 arch/arm64/mm/mmu.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 75df62fea1b6..4e70f4fea06c 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1499,7 +1499,16 @@ static struct notifier_block prevent_bootmem_remove_nb = {
 
 static int __init prevent_bootmem_remove_init(void)
 {
-	return register_memory_notifier(&prevent_bootmem_remove_nb);
+	int ret = 0;
+
+	if (!IS_ENABLED(CONFIG_MEMORY_HOTREMOVE))
+		return ret;
+
+	ret = register_memory_notifier(&prevent_bootmem_remove_nb);
+	if (ret)
+		pr_err("%s: Notifier registration failed %d\n", __func__, ret);
+
+	return ret;
 }
-device_initcall(prevent_bootmem_remove_init);
+early_initcall(prevent_bootmem_remove_init);
 #endif
-- 
2.20.1

