linux-kernel - [PATCH v2 04/27] mm/memory_hotplug: Allow check_hotplug_memory

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Date:   Tue,  3 Dec 2019 14:46:32 +1100
From:   "Alastair D'Silva" <alastair@....ibm.com>
To:     alastair@...ilva.org
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Frederic Barrat <fbarrat@...ux.ibm.com>,
        Andrew Donnellan <ajd@...ux.ibm.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Keith Busch <keith.busch@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Rob Herring <robh@...nel.org>,
        Anton Blanchard <anton@...abs.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
        Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>,
        Cédric Le Goater <clg@...d.org>,
        Anju T Sudhakar <anju@...ux.vnet.ibm.com>,
        Hari Bathini <hbathini@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg Kurz <groug@...d.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Alexey Kardashevskiy <aik@...abs.ru>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-nvdimm@...ts.01.org, linux-mm@...ck.org
Subject: [PATCH v2 04/27] mm/memory_hotplug: Allow check_hotplug_memory_addressable to be called from drivers

From: Alastair D'Silva <alastair@...ilva.org>

When setting up OpenCAPI connected persistent memory, the range check may
not be performed until quite late (or perhaps not at all, if the user does
not establish a DAX device).

This patch makes the range check callable so we can perform the check while
probing the OpenCAPI SCM device.

Signed-off-by: Alastair D'Silva <alastair@...ilva.org>
---
 include/linux/memory_hotplug.h | 5 +++++
 mm/memory_hotplug.c            | 4 ++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index f46ea71b4ffd..3f3a010b60d2 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -339,6 +339,11 @@ static inline int remove_memory(int nid, u64 start, u64 size)
 static inline void __remove_memory(int nid, u64 start, u64 size) {}
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
+#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
+int check_hotplug_memory_addressable(unsigned long pfn,
+		unsigned long nr_pages);
+#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
+
 extern void __ref free_area_init_core_hotplug(int nid);
 extern int __add_memory(int nid, u64 start, u64 size);
 extern int add_memory(int nid, u64 start, u64 size);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index b5be827ecda5..abd9624bd0c1 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -278,8 +278,8 @@ static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
 	return 0;
 }
 
-static int check_hotplug_memory_addressable(unsigned long pfn,
-					    unsigned long nr_pages)
+int check_hotplug_memory_addressable(unsigned long pfn,
+				     unsigned long nr_pages)
 {
 	const u64 max_addr = PFN_PHYS(pfn + nr_pages) - 1;
 
-- 
2.23.0