linux-kernel - [PATCH V5 1/3] arm64/mm/hotplug: Register boot memory hot remove notifier earlier

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Message-Id: <1604896137-16644-2-git-send-email-anshuman.khandual@arm.com>
Date:   Mon,  9 Nov 2020 09:58:55 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     gshan@...hat.com, Anshuman Khandual <anshuman.khandual@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Marc Zyngier <maz@...nel.org>,
        Steve Capper <steve.capper@....com>,
        Mark Brown <broonie@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH V5 1/3] arm64/mm/hotplug: Register boot memory hot remove notifier earlier

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@....com>
Cc: Will Deacon <will@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Marc Zyngier <maz@...nel.org>
Cc: Steve Capper <steve.capper@....com>
Cc: Mark Brown <broonie@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org
Reviewed-by: Gavin Shan <gshan@...hat.com>
Reviewed-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@....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 1c0f3e02f731..71dd9d753b8b 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1510,7 +1510,16 @@ 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