@@ -137,6 +137,7 @@ struct mhp_params {
bool mhp_range_allowed(u64 start, u64 size, bool need_mapping);
struct range mhp_get_pluggable_range(bool need_mapping);
+bool mhp_supports_memmap_on_memory(void);
/*
* Zone resizing functions
@@ -277,6 +278,11 @@ static inline bool movable_node_is_enabl
{
return false;
}
+
+static bool mhp_supports_memmap_on_memory(void)
+{
+ return false;
+}
static inline void pgdat_kswapd_lock(pg_data_t *pgdat) {}
static inline void pgdat_kswapd_unlock(pg_data_t *pgdat) {}
@@ -1337,7 +1337,7 @@ static inline bool arch_supports_memmap_
}
#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_memor
* 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_memor
* 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_memor
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, s
* 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;
The patch titled Subject: mm/memory_hotplug: export mhp_supports_memmap_on_memory() has been added to the -mm mm-unstable branch. Its filename is mm-memory_hotplug-export-mhp_supports_memmap_on_memory.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memory_hotplug-export-mhp_supports_memmap_on_memory.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Vishal Verma <vishal.l.verma@intel.com> Subject: mm/memory_hotplug: export mhp_supports_memmap_on_memory() Date: Wed, 24 Jan 2024 12:03:49 -0800 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. Link: https://lkml.kernel.org/r/20240124-vv-dax_abi-v7-4-20d16cb8d23d@intel.com Cc: Andrew Morton <akpm@linux-foundation.org> Cc: David Hildenbrand <david@redhat.com> 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> Suggested-by: David Hildenbrand <david@redhat.com> Acked-by: David Hildenbrand <david@redhat.com> Signed-off-by: Vishal Verma <vishal.l.verma@intel.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: <nvdimm@lists.linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> --- include/linux/memory_hotplug.h | 6 ++++++ mm/memory_hotplug.c | 17 ++++++----------- 2 files changed, 12 insertions(+), 11 deletions(-)