linux-kernel - [PATCH 2/2] arm64: allow hotpluggable sections to be offlined

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Message-Id: <c5f96b483158871ff65377884955fb0106e43951.1602899443.git.sudaraja@codeaurora.org>
Date:   Fri, 16 Oct 2020 19:02:24 -0700
From:   Sudarshan Rajagopalan <sudaraja@...eaurora.org>
To:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Sudarshan Rajagopalan <sudaraja@...eaurora.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Mark Rutland <mark.rutland@....com>,
        Gavin Shan <gshan@...hat.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        David Hildenbrand <david@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Steven Price <steven.price@....com>,
        Suren Baghdasaryan <surenb@...gle.com>
Subject: [PATCH 2/2] arm64: allow hotpluggable sections to be offlined

On receiving the MEM_GOING_OFFLINE notification, we disallow offlining of
any boot memory by checking if section_early or not. With the introduction
of SECTION_MARK_HOTPLUGGABLE, allow boot mem sections that are marked as
hotpluggable with this bit set to be offlined and removed. This now allows
certain boot mem sections to be offlined.

Signed-off-by: Sudarshan Rajagopalan <sudaraja@...eaurora.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will@...nel.org>
Cc: Anshuman Khandual <anshuman.khandual@....com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Gavin Shan <gshan@...hat.com>
Cc: Logan Gunthorpe <logang@...tatee.com>
Cc: David Hildenbrand <david@...hat.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Steven Price <steven.price@....com>
Cc: Suren Baghdasaryan <surenb@...gle.com>
---
 arch/arm64/mm/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 75df62fea1b6..fb8878698672 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1487,7 +1487,7 @@ static int prevent_bootmem_remove_notifier(struct notifier_block *nb,
 
 	for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 		ms = __pfn_to_section(pfn);
-		if (early_section(ms))
+		if (early_section(ms) && !removable_section(ms))
 			return NOTIFY_BAD;
 	}
 	return NOTIFY_OK;
-- 
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