linux-kernel - [RFC PATCH v3 3/4] mm,memory_hotplug: Enable MHP_MEMMAP_ON

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Date:   Tue,  1 Dec 2020 12:51:57 +0100
From:   Oscar Salvador <osalvador@...e.de>
To:     david@...hat.com
Cc:     mhocko@...nel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, vbabka@...e.cz, pasha.tatashin@...een.com,
        Oscar Salvador <osalvador@...e.de>
Subject: [RFC PATCH v3 3/4] mm,memory_hotplug: Enable MHP_MEMMAP_ON_MEMORY when supported

Let the callers check whether they can use MHP_MEMMAP_ON_MEMORY by
checking mhp_supports_memmap_on_memory().
Currently, we only support MHP_MEMMAP_ON_MEMORY in case
CONFIG_SPARSEMEM_VMEMMAP is enabled, the architecture supports altmap,
and the range to be added spans a single memory block.

Signed-off-by: Oscar Salvador <osalvador@...e.de>
---
 arch/powerpc/platforms/pseries/hotplug-memory.c | 5 ++++-
 drivers/acpi/acpi_memhotplug.c                  | 5 ++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index 7efe6ec5d14a..3aba817e729e 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -612,6 +612,7 @@ static int dlpar_add_lmb(struct drmem_lmb *lmb)
 {
 	unsigned long block_sz;
 	int nid, rc;
+	mhp_t mhp_flags = MHP_NONE;
 
 	if (lmb->flags & DRCONF_MEM_ASSIGNED)
 		return -EINVAL;
@@ -629,8 +630,10 @@ static int dlpar_add_lmb(struct drmem_lmb *lmb)
 	if (nid < 0 || !node_possible(nid))
 		nid = first_online_node;
 
+	if (mhp_supports_memmap_on_memory(block_sz))
+		mhp_flags |= MHP_MEMMAP_ON_MEMORY;
 	/* Add the memory */
-	rc = __add_memory(nid, lmb->base_addr, block_sz, MHP_NONE);
+	rc = __add_memory(nid, lmb->base_addr, block_sz, mhp_flags);
 	if (rc) {
 		invalidate_lmb_associativity_index(lmb);
 		return rc;
diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index b02fd51e5589..1fe645ef0b6c 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -172,6 +172,7 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
 	int result, num_enabled = 0;
 	struct acpi_memory_info *info;
 	int node;
+	mhp_t mhp_flags = MHP_NONE;
 
 	node = acpi_get_node(handle);
 	/*
@@ -194,8 +195,10 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
 		if (node < 0)
 			node = memory_add_physaddr_to_nid(info->start_addr);
 
+		if (mhp_supports_memmap_on_memory(info->length))
+			mhp_flags |= MHP_MEMMAP_ON_MEMORY;
 		result = __add_memory(node, info->start_addr, info->length,
-				      MHP_NONE);
+				      mhp_flags);
 
 		/*
 		 * If the memory block has been used by the kernel, add_memory()
-- 
2.26.2