[PATCH v1 05/12] mm/memory_hotplug: remove nid parameter from remove_memory() and friends

[PATCH v1 05/12] mm/memory_hotplug: remove nid parameter from remove_memory() and friends

[David Hildenbrand]

There is only a single user remaining. We can simply try to offline all
online nodes - which is fast, because we usually span pages and can skip
such nodes right away.

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                           | 20 +++++++++----------
 6 files changed, 23 insertions(+), 30 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index 8377f1f7c78e..4a9232ddbefe 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;
 	}
 
@@ -386,7 +385,7 @@ 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 */
@@ -638,7 +637,7 @@ 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 10ec60d81e84..e327fb878143 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -673,7 +673,7 @@ 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);
 		/*
@@ -728,7 +728,7 @@ 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 1d8d09c029c9..84f05435e2ae 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -319,9 +319,9 @@ 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) {}
@@ -331,12 +331,12 @@ 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 f9be66bbd847..9cae42636f3e 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -2157,9 +2157,9 @@ 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;
+	int rc = 0, nid;
 	struct vmem_altmap mhp_altmap = {};
 	struct vmem_altmap *altmap = NULL;
 	unsigned long nr_vmemmap_pages;
@@ -2220,7 +2220,8 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
 
 	release_mem_region_adjustable(start, size);
 
-	try_offline_node(nid);
+	for_each_online_node(nid)
+		try_offline_node(nid);
 
 	mem_hotplug_done();
 	return 0;
@@ -2228,7 +2229,6 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
 
 /**
  * remove_memory
- * @nid: the node ID
  * @start: physical address of the region to remove
  * @size: size of the region to remove
  *
@@ -2236,14 +2236,14 @@ 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();
 }
 
@@ -2251,12 +2251,12 @@ 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;
@@ -2316,7 +2316,7 @@ 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;
@@ -2352,7 +2352,7 @@ 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

Re: [PATCH v1 05/12] mm/memory_hotplug: remove nid parameter from remove_memory() and friends

[Michael Ellerman]

David Hildenbrand <david@redhat.com> writes:
> There is only a single user remaining. We can simply try to offline all
> online nodes - which is fast, because we usually span pages and can skip
> such nodes right away.

That makes me slightly nervous, because our big powerpc boxes tend to
trip on these scaling issues before others.

But the spanned pages check is just:

void try_offline_node(int nid)
{
	pg_data_t *pgdat = NODE_DATA(nid);
        ...
	if (pgdat->node_spanned_pages)
		return;

So I guess that's pretty cheap, and it's only O(nodes), which should
never get that big.

> 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                           | 20 +++++++++----------
>  6 files changed, 23 insertions(+), 30 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
> index 8377f1f7c78e..4a9232ddbefe 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;
>  	}
>  
> @@ -386,7 +385,7 @@ 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 */
> @@ -638,7 +637,7 @@ 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;


Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

cheers

Re: [PATCH v1 05/12] mm/memory_hotplug: remove nid parameter from remove_memory() and friends

[David Hildenbrand]

On 08.06.21 13:11, Michael Ellerman wrote:
> David Hildenbrand <david@redhat.com> writes:
>> There is only a single user remaining. We can simply try to offline all
>> online nodes - which is fast, because we usually span pages and can skip
>> such nodes right away.
> 
> That makes me slightly nervous, because our big powerpc boxes tend to
> trip on these scaling issues before others.
> 
> But the spanned pages check is just:
> 
> void try_offline_node(int nid)
> {
> 	pg_data_t *pgdat = NODE_DATA(nid);
>          ...
> 	if (pgdat->node_spanned_pages)
> 		return;
> 
> So I guess that's pretty cheap, and it's only O(nodes), which should
> never get that big.

Exactly. And if it does turn out to be a problem, we can walk all memory 
blocks before removing them, collecting the nid(s).

-- 
Thanks,

David / dhildenb

Re: [PATCH v1 05/12] mm/memory_hotplug: remove nid parameter from remove_memory() and friends

[David Hildenbrand]

On 08.06.21 13:18, David Hildenbrand wrote:
> On 08.06.21 13:11, Michael Ellerman wrote:
>> David Hildenbrand <david@redhat.com> writes:
>>> There is only a single user remaining. We can simply try to offline all
>>> online nodes - which is fast, because we usually span pages and can skip
>>> such nodes right away.
>>
>> That makes me slightly nervous, because our big powerpc boxes tend to
>> trip on these scaling issues before others.
>>
>> But the spanned pages check is just:
>>
>> void try_offline_node(int nid)
>> {
>> 	pg_data_t *pgdat = NODE_DATA(nid);
>>           ...
>> 	if (pgdat->node_spanned_pages)
>> 		return;
>>
>> So I guess that's pretty cheap, and it's only O(nodes), which should
>> never get that big.
> 
> Exactly. And if it does turn out to be a problem, we can walk all memory
> blocks before removing them, collecting the nid(s).
> 

I might just do the following on top:

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 61bff8f3bfb1..bbc26fdac364 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -2176,7 +2176,9 @@ 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;
  
@@ -2271,10 +2273,10 @@ EXPORT_SYMBOL(try_offline_node);
  
  static int __ref try_remove_memory(u64 start, u64 size)
  {
-       int rc = 0, nid;
         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));
  
@@ -2282,8 +2284,12 @@ static int __ref try_remove_memory(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;
  
@@ -2332,7 +2338,7 @@ static int __ref try_remove_memory(u64 start, u64 size)
  
         release_mem_region_adjustable(start, size);
  
-       for_each_online_node(nid)
+       if (nid != NUMA_NO_NODE)
                 try_offline_node(nid);
  
         mem_hotplug_done();



-- 
Thanks,

David / dhildenb