[PATCH v1 3/4] mm/memory_hotplug: remove nid parameter from remove_memory() and friends

[David Hildenbrand <david@redhat.com>]

There is only a single user remaining. We can simply lookup the nid only
used for node offlining purposes when walking our memory blocks. We
don't expect to remove multi-nid ranges; and if we'd ever do, we most
probably don't care about removing multi-nid ranges that actually result
in empty nodes.

If ever required, we can detect the "multi-nid" scenario and simply try
offlining all online nodes.

Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-acpi@vger.kernel.org
Cc: nvdimm@lists.linux.dev
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 .../platforms/pseries/hotplug-memory.c        |  9 +++---
 drivers/acpi/acpi_memhotplug.c                |  7 +----
 drivers/dax/kmem.c                            |  3 +-
 drivers/virtio/virtio_mem.c                   |  4 +--
 include/linux/memory_hotplug.h                | 10 +++----
 mm/memory_hotplug.c                           | 28 +++++++++++--------
 6 files changed, 30 insertions(+), 31 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index 377d852f5a9a..ef5c24b42cf1 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -286,7 +286,7 @@ static int pseries_remove_memblock(unsigned long base, unsigned long memblock_si
 {
 	unsigned long block_sz, start_pfn;
 	int sections_per_block;
-	int i, nid;
+	int i;
 
 	start_pfn = base >> PAGE_SHIFT;
 
@@ -297,10 +297,9 @@ static int pseries_remove_memblock(unsigned long base, unsigned long memblock_si
 
 	block_sz = pseries_memory_block_size();
 	sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
-	nid = memory_add_physaddr_to_nid(base);
 
 	for (i = 0; i < sections_per_block; i++) {
-		__remove_memory(nid, base, MIN_MEMORY_BLOCK_SIZE);
+		__remove_memory(base, MIN_MEMORY_BLOCK_SIZE);
 		base += MIN_MEMORY_BLOCK_SIZE;
 	}
 
@@ -387,7 +386,7 @@ static int dlpar_remove_lmb(struct drmem_lmb *lmb)
 
 	block_sz = pseries_memory_block_size();
 
-	__remove_memory(mem_block->nid, lmb->base_addr, block_sz);
+	__remove_memory(lmb->base_addr, block_sz);
 	put_device(&mem_block->dev);
 
 	/* Update memory regions for memory remove */
@@ -660,7 +659,7 @@ static int dlpar_add_lmb(struct drmem_lmb *lmb)
 
 	rc = dlpar_online_lmb(lmb);
 	if (rc) {
-		__remove_memory(nid, lmb->base_addr, block_sz);
+		__remove_memory(lmb->base_addr, block_sz);
 		invalidate_lmb_associativity_index(lmb);
 	} else {
 		lmb->flags |= DRCONF_MEM_ASSIGNED;
diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index 8cc195c4c861..1d01d9414c40 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -239,19 +239,14 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
 
 static void acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
 {
-	acpi_handle handle = mem_device->device->handle;
 	struct acpi_memory_info *info, *n;
-	int nid = acpi_get_node(handle);
 
 	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
 		if (!info->enabled)
 			continue;
 
-		if (nid == NUMA_NO_NODE)
-			nid = memory_add_physaddr_to_nid(info->start_addr);
-
 		acpi_unbind_memory_blocks(info);
-		__remove_memory(nid, info->start_addr, info->length);
+		__remove_memory(info->start_addr, info->length);
 		list_del(&info->list);
 		kfree(info);
 	}
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index ac231cc36359..99e0f60c4c26 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -156,8 +156,7 @@ static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
 		if (rc)
 			continue;
 
-		rc = remove_memory(dev_dax->target_node, range.start,
-				range_len(&range));
+		rc = remove_memory(range.start, range_len(&range));
 		if (rc == 0) {
 			release_resource(data->res[i]);
 			kfree(data->res[i]);
diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 09ed55de07d7..774986695dc4 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -677,7 +677,7 @@ static int virtio_mem_remove_memory(struct virtio_mem *vm, uint64_t addr,
 
 	dev_dbg(&vm->vdev->dev, "removing memory: 0x%llx - 0x%llx\n", addr,
 		addr + size - 1);
-	rc = remove_memory(vm->nid, addr, size);
+	rc = remove_memory(addr, size);
 	if (!rc) {
 		atomic64_sub(size, &vm->offline_size);
 		/*
@@ -720,7 +720,7 @@ static int virtio_mem_offline_and_remove_memory(struct virtio_mem *vm,
 		"offlining and removing memory: 0x%llx - 0x%llx\n", addr,
 		addr + size - 1);
 
-	rc = offline_and_remove_memory(vm->nid, addr, size);
+	rc = offline_and_remove_memory(addr, size);
 	if (!rc) {
 		atomic64_sub(size, &vm->offline_size);
 		/*
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 010a192298b5..068e3dcf4690 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -292,9 +292,9 @@ static inline void pgdat_resize_init(struct pglist_data *pgdat) {}
 
 extern void try_offline_node(int nid);
 extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
-extern int remove_memory(int nid, u64 start, u64 size);
-extern void __remove_memory(int nid, u64 start, u64 size);
-extern int offline_and_remove_memory(int nid, u64 start, u64 size);
+extern int remove_memory(u64 start, u64 size);
+extern void __remove_memory(u64 start, u64 size);
+extern int offline_and_remove_memory(u64 start, u64 size);
 
 #else
 static inline void try_offline_node(int nid) {}
@@ -304,12 +304,12 @@ static inline int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 	return -EINVAL;
 }
 
-static inline int remove_memory(int nid, u64 start, u64 size)
+static inline int remove_memory(u64 start, u64 size)
 {
 	return -EBUSY;
 }
 
-static inline void __remove_memory(int nid, u64 start, u64 size) {}
+static inline void __remove_memory(u64 start, u64 size) {}
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
 extern void set_zone_contiguous(struct zone *zone);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index f2a9af3af184..388c8627f17f 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1745,7 +1745,9 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 static int check_memblock_offlined_cb(struct memory_block *mem, void *arg)
 {
 	int ret = !is_memblock_offlined(mem);
+	int *nid = arg;
 
+	*nid = mem->nid;
 	if (unlikely(ret)) {
 		phys_addr_t beginpa, endpa;
 
@@ -1838,12 +1840,12 @@ void try_offline_node(int nid)
 }
 EXPORT_SYMBOL(try_offline_node);
 
-static int __ref try_remove_memory(int nid, u64 start, u64 size)
+static int __ref try_remove_memory(u64 start, u64 size)
 {
-	int rc = 0;
 	struct vmem_altmap mhp_altmap = {};
 	struct vmem_altmap *altmap = NULL;
 	unsigned long nr_vmemmap_pages;
+	int rc = 0, nid = NUMA_NO_NODE;
 
 	BUG_ON(check_hotplug_memory_range(start, size));
 
@@ -1851,8 +1853,12 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
 	 * All memory blocks must be offlined before removing memory.  Check
 	 * whether all memory blocks in question are offline and return error
 	 * if this is not the case.
+	 *
+	 * While at it, determine the nid. Note that if we'd have mixed nodes,
+	 * we'd only try to offline the last determined one -- which is good
+	 * enough for the cases we care about.
 	 */
-	rc = walk_memory_blocks(start, size, NULL, check_memblock_offlined_cb);
+	rc = walk_memory_blocks(start, size, &nid, check_memblock_offlined_cb);
 	if (rc)
 		return rc;
 
@@ -1901,7 +1907,8 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
 
 	release_mem_region_adjustable(start, size);
 
-	try_offline_node(nid);
+	if (nid != NUMA_NO_NODE)
+		try_offline_node(nid);
 
 	mem_hotplug_done();
 	return 0;
@@ -1909,7 +1916,6 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
 
 /**
  * __remove_memory - Remove memory if every memory block is offline
- * @nid: the node ID
  * @start: physical address of the region to remove
  * @size: size of the region to remove
  *
@@ -1917,14 +1923,14 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
  * and online/offline operations before this call, as required by
  * try_offline_node().
  */
-void __remove_memory(int nid, u64 start, u64 size)
+void __remove_memory(u64 start, u64 size)
 {
 
 	/*
 	 * trigger BUG() if some memory is not offlined prior to calling this
 	 * function
 	 */
-	if (try_remove_memory(nid, start, size))
+	if (try_remove_memory(start, size))
 		BUG();
 }
 
@@ -1932,12 +1938,12 @@ void __remove_memory(int nid, u64 start, u64 size)
  * Remove memory if every memory block is offline, otherwise return -EBUSY is
  * some memory is not offline
  */
-int remove_memory(int nid, u64 start, u64 size)
+int remove_memory(u64 start, u64 size)
 {
 	int rc;
 
 	lock_device_hotplug();
-	rc  = try_remove_memory(nid, start, size);
+	rc = try_remove_memory(start, size);
 	unlock_device_hotplug();
 
 	return rc;
@@ -1997,7 +2003,7 @@ static int try_reonline_memory_block(struct memory_block *mem, void *arg)
  * unplugged all memory (so it's no longer in use) and want to offline + remove
  * that memory.
  */
-int offline_and_remove_memory(int nid, u64 start, u64 size)
+int offline_and_remove_memory(u64 start, u64 size)
 {
 	const unsigned long mb_count = size / memory_block_size_bytes();
 	uint8_t *online_types, *tmp;
@@ -2033,7 +2039,7 @@ int offline_and_remove_memory(int nid, u64 start, u64 size)
 	 * This cannot fail as it cannot get onlined in the meantime.
 	 */
 	if (!rc) {
-		rc = try_remove_memory(nid, start, size);
+		rc = try_remove_memory(start, size);
 		if (rc)
 			pr_err("%s: Failed to remove memory: %d", __func__, rc);
 	}
-- 
2.31.1