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authorVishal Verma <vishal.l.verma@intel.com>2024-01-24 12:03:49 -0800
committerAndrew Morton <akpm@linux-foundation.org>2024-02-22 10:24:40 -0800
commit42d9358252e5d055223487d9f653c2a2ac859a2a (patch)
tree8241baa583063c3996f0e8b0ff56a294506853d7 /mm/memory_hotplug.c
parent51e7849cd6e4050599ef4e255e85195788841bb4 (diff)
downloadlwn-42d9358252e5d055223487d9f653c2a2ac859a2a.tar.gz
lwn-42d9358252e5d055223487d9f653c2a2ac859a2a.zip
mm/memory_hotplug: export mhp_supports_memmap_on_memory()
In preparation for adding sysfs ABI to toggle memmap_on_memory semantics for drivers adding memory, export the mhp_supports_memmap_on_memory() helper. This allows drivers to check if memmap_on_memory support is available before trying to request it, and display an appropriate message if it isn't available. As part of this, remove the size argument to this - with recent updates to allow memmap_on_memory for larger ranges, and the internal splitting of altmaps into respective memory blocks, the size argument is meaningless. [akpm@linux-foundation.org: fix build] Link: https://lkml.kernel.org/r/20240124-vv-dax_abi-v7-4-20d16cb8d23d@intel.com Signed-off-by: Vishal Verma <vishal.l.verma@intel.com> Acked-by: David Hildenbrand <david@redhat.com> Suggested-by: David Hildenbrand <david@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Li Zhijian <lizhijian@fujitsu.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Jiang <dave.jiang@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Huang Ying <ying.huang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/memory_hotplug.c')
-rw-r--r--mm/memory_hotplug.c17
1 files changed, 6 insertions, 11 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 707027f69150..a444e2d7dd2b 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1337,7 +1337,7 @@ static inline bool arch_supports_memmap_on_memory(unsigned long vmemmap_size)
}
#endif
-static bool mhp_supports_memmap_on_memory(unsigned long size)
+bool mhp_supports_memmap_on_memory(void)
{
unsigned long vmemmap_size = memory_block_memmap_size();
unsigned long memmap_pages = memory_block_memmap_on_memory_pages();
@@ -1346,17 +1346,11 @@ static bool mhp_supports_memmap_on_memory(unsigned long size)
* Besides having arch support and the feature enabled at runtime, we
* need a few more assumptions to hold true:
*
- * a) We span a single memory block: memory onlining/offlinin;g happens
- * in memory block granularity. We don't want the vmemmap of online
- * memory blocks to reside on offline memory blocks. In the future,
- * we might want to support variable-sized memory blocks to make the
- * feature more versatile.
- *
- * b) The vmemmap pages span complete PMDs: We don't want vmemmap code
+ * a) The vmemmap pages span complete PMDs: We don't want vmemmap code
* to populate memory from the altmap for unrelated parts (i.e.,
* other memory blocks)
*
- * c) The vmemmap pages (and thereby the pages that will be exposed to
+ * b) The vmemmap pages (and thereby the pages that will be exposed to
* the buddy) have to cover full pageblocks: memory onlining/offlining
* code requires applicable ranges to be page-aligned, for example, to
* set the migratetypes properly.
@@ -1368,7 +1362,7 @@ static bool mhp_supports_memmap_on_memory(unsigned long size)
* altmap as an alternative source of memory, and we do not exactly
* populate a single PMD.
*/
- if (!mhp_memmap_on_memory() || size != memory_block_size_bytes())
+ if (!mhp_memmap_on_memory())
return false;
/*
@@ -1391,6 +1385,7 @@ static bool mhp_supports_memmap_on_memory(unsigned long size)
return arch_supports_memmap_on_memory(vmemmap_size);
}
+EXPORT_SYMBOL_GPL(mhp_supports_memmap_on_memory);
static void __ref remove_memory_blocks_and_altmaps(u64 start, u64 size)
{
@@ -1526,7 +1521,7 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
* Self hosted memmap array
*/
if ((mhp_flags & MHP_MEMMAP_ON_MEMORY) &&
- mhp_supports_memmap_on_memory(memory_block_size_bytes())) {
+ mhp_supports_memmap_on_memory()) {
ret = create_altmaps_and_memory_blocks(nid, group, start, size, mhp_flags);
if (ret)
goto error;