The patch titled
Subject: mm,memory_hotplug: add kernel boot option to enable memmap_on_memory
has been removed from the -mm tree. Its filename was
mmmemory_hotplug-add-kernel-boot-option-to-enable-memmap_on_memory.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Oscar Salvador <osalvador@xxxxxxx>
Subject: mm,memory_hotplug: add kernel boot option to enable memmap_on_memory
Self stored memmap leads to a sparse memory situation which is unsuitable
for workloads that requires large contiguous memory chunks, so make this
an opt-in which needs to be explicitly enabled.
To control this, let memory_hotplug have its own memory space, as
suggested by David, so we can add memory_hotplug.memmap_on_memory
parameter.
Link: https://lkml.kernel.org/r/20210421102701.25051-7-osalvador@xxxxxxx
Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/admin-guide/kernel-parameters.txt | 17 ++++++++++++++
mm/Makefile | 5 +++-
mm/memory_hotplug.c | 10 +++++++-
3 files changed, 30 insertions(+), 2 deletions(-)
--- a/Documentation/admin-guide/kernel-parameters.txt~mmmemory_hotplug-add-kernel-boot-option-to-enable-memmap_on_memory
+++ a/Documentation/admin-guide/kernel-parameters.txt
@@ -2801,6 +2801,23 @@
seconds. Use this parameter to check at some
other rate. 0 disables periodic checking.
+ memory_hotplug.memmap_on_memory
+ [KNL,X86,ARM] Boolean flag to enable this feature.
+ Format: {on | off (default)}
+ When enabled, runtime hotplugged memory will
+ allocate its internal metadata (struct pages)
+ from the hotadded memory which will allow to
+ hotadd a lot of memory without requiring
+ additional memory to do so.
+ This feature is disabled by default because it
+ has some implication on large (e.g. GB)
+ allocations in some configurations (e.g. small
+ memory blocks).
+ The state of the flag can be read in
+ /sys/module/memory_hotplug/parameters/memmap_on_memory.
+ Note that even when enabled, there are a few cases where
+ the feature is not effective.
+
memtest= [KNL,X86,ARM,PPC] Enable memtest
Format: <integer>
default : 0 <disable>
--- a/mm/Makefile~mmmemory_hotplug-add-kernel-boot-option-to-enable-memmap_on_memory
+++ a/mm/Makefile
@@ -58,9 +58,13 @@ obj-y := filemap.o mempool.o oom_kill.
page-alloc-y := page_alloc.o
page-alloc-$(CONFIG_SHUFFLE_PAGE_ALLOCATOR) += shuffle.o
+# Give 'memory_hotplug' its own module-parameter namespace
+memory-hotplug-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
+
obj-y += page-alloc.o
obj-y += init-mm.o
obj-y += memblock.o
+obj-y += $(memory-hotplug-y)
ifdef CONFIG_MMU
obj-$(CONFIG_ADVISE_SYSCALLS) += madvise.o
@@ -83,7 +87,6 @@ obj-$(CONFIG_SLUB) += slub.o
obj-$(CONFIG_KASAN) += kasan/
obj-$(CONFIG_KFENCE) += kfence/
obj-$(CONFIG_FAILSLAB) += failslab.o
-obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
obj-$(CONFIG_MEMTEST) += memtest.o
obj-$(CONFIG_MIGRATION) += migrate.o
obj-$(CONFIG_TRANSPARENT_HUGEPAGE) += huge_memory.o khugepaged.o
--- a/mm/memory_hotplug.c~mmmemory_hotplug-add-kernel-boot-option-to-enable-memmap_on_memory
+++ a/mm/memory_hotplug.c
@@ -42,7 +42,15 @@
#include "internal.h"
#include "shuffle.h"
-static bool memmap_on_memory;
+
+/*
+ * memory_hotplug.memmap_on_memory parameter
+ */
+static bool memmap_on_memory __ro_after_init;
+#ifdef CONFIG_MHP_MEMMAP_ON_MEMORY
+module_param(memmap_on_memory, bool, 0444);
+MODULE_PARM_DESC(memmap_on_memory, "Enable memmap on memory for memory hotplug");
+#endif
/*
* online_page_callback contains pointer to current page onlining function.
_
Patches currently in -mm which might be from osalvador@xxxxxxx are
