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From:   Chris Goldsworthy <quic_cgoldswo@quicinc.com>
To:     Andrew Morton <akpm@linux-foundation.org>
CC:     David Hildenbrand <david@redhat.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        "Sudarshan Rajagopalan" <quic_sudaraja@quicinc.com>,
        Georgi Djakov <quic_c_gdjako@quicinc.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
        Chris Goldsworthy <quic_cgoldswo@quicinc.com>,
        Florian Fainelli <f.fainelli@gmail.com>
Subject: [PATCH] arm64: mm: update max_pfn after memory hotplug
Date:   Tue, 28 Sep 2021 11:51:49 -0700
Message-ID: <a51a27ee7be66024b5ce626310d673f24107bcb8.1632853776.git.quic_cgoldswo@quicinc.com>
In-Reply-To: <cover.1632853776.git.quic_cgoldswo@quicinc.com>
References: <cover.1632853776.git.quic_cgoldswo@quicinc.com>
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From: Sudarshan Rajagopalan <quic_sudaraja@quicinc.com>

After new memory blocks have been hotplugged, max_pfn and max_low_pfn
needs updating to reflect on new PFNs being hot added to system.
Without this patch, debug-related functions that use max_pfn such as
get_max_dump_pfn() or read_page_owner() will not work with any page in
memory that is hot-added after boot. 

Fixes: 4ab215061554 ("arm64: Add memory hotplug support")
Signed-off-by: Sudarshan Rajagopalan <quic_sudaraja@quicinc.com>
Signed-off-by: Chris Goldsworthy <quic_cgoldswo@quicinc.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Georgi Djakov <quic_c_gdjako@quicinc.com>
---
 arch/arm64/mm/mmu.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index cfd9deb..fd85b51 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1499,6 +1499,11 @@ int arch_add_memory(int nid, u64 start, u64 size,
 	if (ret)
 		__remove_pgd_mapping(swapper_pg_dir,
 				     __phys_to_virt(start), size);
+	else {
+		max_pfn = PFN_UP(start + size);
+		max_low_pfn = max_pfn;
+	}
+
 	return ret;
 }
 
-- 
2.7.4