On 25.07.23 12:02, Aneesh Kumar K.V wrote:
With memmap on memory, some architecture needs more details w.r.t altmap
such as base_pfn, end_pfn, etc to unmap vmemmap memory. Instead of
computing them again when we remove a memory block, embed vmem_altmap
details in struct memory_block if we are using memmap on memory block
feature.
No functional change in this patch
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
---
[...]
static int add_memory_block(unsigned long block_id, unsigned long state,
- unsigned long nr_vmemmap_pages,
+ struct vmem_altmap *altmap,
struct memory_group *group)
{
struct memory_block *mem;
@@ -744,7 +751,14 @@ static int add_memory_block(unsigned long block_id, unsigned long state,
mem->start_section_nr = block_id * sections_per_block;
mem->state = state;
mem->nid = NUMA_NO_NODE;
- mem->nr_vmemmap_pages = nr_vmemmap_pages;
+ if (altmap) {
+ mem->altmap = kmalloc(sizeof(struct vmem_altmap), GFP_KERNEL);
+ if (!mem->altmap) {
+ kfree(mem);
+ return -ENOMEM;
+ }
+ memcpy(mem->altmap, altmap, sizeof(*altmap));
+ }
I'm wondering if we should instead let the caller do the alloc/free. So we would alloc
int the caller and would only store the pointer.
Before removing the memory block, we would clear the pointer and free it in the caller.
IOW, when removing a memory block and we still have an altmap set, something would be wrong.
See below on try_remove_memory() handling.
[...]
-static int get_nr_vmemmap_pages_cb(struct memory_block *mem, void *arg)
+static int get_vmemmap_altmap_cb(struct memory_block *mem, void *arg)
{
+ struct vmem_altmap *altmap = (struct vmem_altmap *)arg;
/*
- * If not set, continue with the next block.
+ * If we have any pages allocated from altmap
+ * return the altmap details and break callback.
*/
- return mem->nr_vmemmap_pages;
+ if (mem->altmap) {
+ memcpy(altmap, mem->altmap, sizeof(struct vmem_altmap));
+ return 1;
+ }
+ return 0;
}
static int check_cpu_on_node(int nid)
@@ -2146,9 +2152,8 @@ EXPORT_SYMBOL(try_offline_node);
static int __ref try_remove_memory(u64 start, u64 size)
{
- struct vmem_altmap mhp_altmap = {};
- struct vmem_altmap *altmap = NULL;
- unsigned long nr_vmemmap_pages;
+ int ret;
+ struct vmem_altmap mhp_altmap, *altmap = NULL;
int rc = 0, nid = NUMA_NO_NODE;
BUG_ON(check_hotplug_memory_range(start, size));
@@ -2171,24 +2176,15 @@ static int __ref try_remove_memory(u64 start, u64 size)
* the same granularity it was added - a single memory block.
*/
if (mhp_memmap_on_memory()) {
- nr_vmemmap_pages = walk_memory_blocks(start, size, NULL,
- get_nr_vmemmap_pages_cb);
- if (nr_vmemmap_pages) {
+ ret = walk_memory_blocks(start, size, &mhp_altmap,
+ get_vmemmap_altmap_cb);
+ if (ret) {
if (size != memory_block_size_bytes()) {
pr_warn("Refuse to remove %#llx - %#llx,"
"wrong granularity\n",
start, start + size);
return -EINVAL;
}
-
- /*
- * Let remove_pmd_table->free_hugepage_table do the
- * right thing if we used vmem_altmap when hot-adding
- * the range.
- */
- mhp_altmap.base_pfn = PHYS_PFN(start);
- mhp_altmap.free = nr_vmemmap_pages;
- mhp_altmap.alloc = nr_vmemmap_pages;
altmap = &mhp_altmap;
}
Instead of that, I suggest (whitespace damage expected):
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 3f231cf1b410..f6860df64549 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1956,12 +1956,19 @@ static int check_memblock_offlined_cb(struct memory_block *mem, void *arg)
return 0;
}
-static int get_nr_vmemmap_pages_cb(struct memory_block *mem, void *arg)
+static int test_has_altmap_cb(struct memory_block *mem, void *arg)
{
- /*
- * If not set, continue with the next block.
- */
- return mem->nr_vmemmap_pages;
+ struct memory_block **mem_ptr = (struct memory_block **)arg;
+
+ if (mem->altmap) {
+ /*
+ * We're not taking a reference on the memory block; it
+ * it cannot vanish while we're about to that memory ourselves.
+ */
+ *mem_ptr = mem;
+ return 1;
+ }
+ return 0;
}
static int check_cpu_on_node(int nid)
@@ -2036,9 +2043,7 @@ EXPORT_SYMBOL(try_offline_node);
static int __ref try_remove_memory(u64 start, u64 size)
{
- 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));
@@ -2061,9 +2066,9 @@ static int __ref try_remove_memory(u64 start, u64 size)
* the same granularity it was added - a single memory block.
*/
if (mhp_memmap_on_memory()) {
- nr_vmemmap_pages = walk_memory_blocks(start, size, NULL,
- get_nr_vmemmap_pages_cb);
- if (nr_vmemmap_pages) {
+ struct memory_block *mem;
+
+ if (walk_memory_blocks(start, size, &mem, test_has_altmap_cb)) {
if (size != memory_block_size_bytes()) {
pr_warn("Refuse to remove %#llx - %#llx,"
"wrong granularity\n",
@@ -2072,12 +2077,11 @@ static int __ref try_remove_memory(u64 start, u64 size)
}
/*
- * Let remove_pmd_table->free_hugepage_table do the
- * right thing if we used vmem_altmap when hot-adding
- * the range.
+ * Clear the altmap from the memory block before we
+ * remove it; we'll take care of freeing the altmap.
*/
- mhp_altmap.alloc = nr_vmemmap_pages;
- altmap = &mhp_altmap;
+ altmap = mem->altmap;
+ mem->altmap = NULL;
}
}
@@ -2094,6 +2098,9 @@ static int __ref try_remove_memory(u64 start, u64 size)
arch_remove_memory(start, size, altmap);
+ if (altmap)
+ kfree(altmap);
+
if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {
memblock_phys_free(start, size);
memblock_remove(start, size);
