On 06.07.23 12:04, Aneesh Kumar K V wrote:
On 7/6/23 2:54 PM, David Hildenbrand wrote:
On 06.07.23 10:50, Aneesh Kumar K.V wrote:
Instead of checking for memmap on memory feature enablement within the
functions checking for alignment, use the kernel parameter to control the
memory hotplug flags. The generic kernel now enables memmap on memory
feature if the hotplug flag request for the same.
The ACPI code now can pass the flag unconditionally because the kernel will
fallback to not using the feature if the alignment rules are not met.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
---
drivers/acpi/acpi_memhotplug.c | 3 +--
include/linux/memory_hotplug.h | 14 ++++++++++++++
mm/memory_hotplug.c | 35 +++++++++++-----------------------
3 files changed, 26 insertions(+), 26 deletions(-)
diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index 24f662d8bd39..4d0096fc4cc2 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -211,8 +211,7 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
if (!info->length)
continue;
- if (mhp_supports_memmap_on_memory(info->length))
- mhp_flags |= MHP_MEMMAP_ON_MEMORY;
+ mhp_flags |= get_memmap_on_memory_flags();
result = __add_memory(mgid, info->start_addr, info->length,
mhp_flags);
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index a769f44b8368..af7017122506 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -358,4 +358,18 @@ bool mhp_supports_memmap_on_memory(unsigned long size);
bool __mhp_supports_memmap_on_memory(unsigned long size);
#endif /* CONFIG_MEMORY_HOTPLUG */
+#ifdef CONFIG_MHP_MEMMAP_ON_MEMORY
+extern bool memmap_on_memory;
+static inline unsigned long get_memmap_on_memory_flags(void)
+{
+ if (memmap_on_memory)
+ return MHP_MEMMAP_ON_MEMORY;
+ return 0;
+}
+#else
+static inline unsigned long get_memmap_on_memory_flags(void)
+{
+ return 0;
+}
+#endif
That's kind-of ugly TBH.
Why do we need this change?
I was trying to avoid rest of the kernel doing
if (mhp_supports_memmap_on_memory(info->length))
mhp_flags |= MHP_MEMMAP_ON_MEMORY;
It would look much cleaner if you would simply have:
mhp_flags |= MHP_MEMMAP_ON_MEMORY;
result = __add_memory(mgid, info->start_addr, info->length, mhp_flags);
And modify the semantics of MHP_MEMMAP_ON_MEMORY to mean "allocate the
memmap from hotplugged memory if supported and enabled globally".
Then, we can simply ignore the flag in __add_memory() if either the
global toggle is off or if it's not supported for the range / by the arch.
Maybe, in the future we want more fine-grained control (as asked by
dax/kmem) and maybe not have the global toggle. But for now, that should
be good enough I guess.
--
Cheers,
David / dhildenb
