The patch titled
Subject: mm: memory_hotplug: override memmap_on_memory when hugetlb_free_vmemmap=on
has been added to the -mm mm-unstable branch. Its filename is
mm-memory_hotplug-override-memmap_on_memory-when-hugetlb_free_vmemmap=on.patch
This patch should soon appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Subject: mm: memory_hotplug: override memmap_on_memory when hugetlb_free_vmemmap=on
When "hugetlb_free_vmemmap=on" and "memory_hotplug.memmap_on_memory" are
both passed to boot cmdline, the variable of "memmap_on_memory" will be
set to 1 even if the vmemmap pages will not be allocated from the hotadded
memory since the former takes precedence over the latter. In the next
patch, we want to enable or disable the feature of freeing vmemmap pages
of HugeTLB via sysctl. We need a way to know if the feature of
memory_hotplug.memmap_on_memory is enabled when enabling the feature of
freeing vmemmap pages since those two features are not compatible,
however, the variable of "memmap_on_memory" cannot indicate this nowadays.
Do not set "memmap_on_memory" to 1 when both parameters are passed to
cmdline, in this case, "memmap_on_memory" could indicate if this feature
is enabled by the users.
Also introduce mhp_memmap_on_memory() helper to move the definition of
"memmap_on_memory" to the scope of CONFIG_MHP_MEMMAP_ON_MEMORY. In the
next patch, mhp_memmap_on_memory() will also be exported to be used in
hugetlb_vmemmap.c.
Link: https://lkml.kernel.org/r/20220429121816.37541-3-songmuchun@xxxxxxxxxxxxx
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Iurii Zaikin <yzaikin@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Xiongchun Duan <duanxiongchun@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory_hotplug.c | 32 ++++++++++++++++++++++++++------
1 file changed, 26 insertions(+), 6 deletions(-)
--- a/mm/memory_hotplug.c~mm-memory_hotplug-override-memmap_on_memory-when-hugetlb_free_vmemmap=on
+++ a/mm/memory_hotplug.c
@@ -42,14 +42,36 @@
#include "internal.h"
#include "shuffle.h"
+#ifdef CONFIG_MHP_MEMMAP_ON_MEMORY
+static int memmap_on_memory_set(const char *val, const struct kernel_param *kp)
+{
+ if (hugetlb_optimize_vmemmap_enabled())
+ return 0;
+ return param_set_bool(val, kp);
+}
+
+static const struct kernel_param_ops memmap_on_memory_ops = {
+ .flags = KERNEL_PARAM_OPS_FL_NOARG,
+ .set = memmap_on_memory_set,
+ .get = param_get_bool,
+};
/*
* 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_param_cb(memmap_on_memory, &memmap_on_memory_ops, &memmap_on_memory, 0444);
MODULE_PARM_DESC(memmap_on_memory, "Enable memmap on memory for memory hotplug");
+
+static inline bool mhp_memmap_on_memory(void)
+{
+ return memmap_on_memory;
+}
+#else
+static inline bool mhp_memmap_on_memory(void)
+{
+ return false;
+}
#endif
enum {
@@ -1289,9 +1311,7 @@ bool mhp_supports_memmap_on_memory(unsig
* altmap as an alternative source of memory, and we do not exactly
* populate a single PMD.
*/
- return memmap_on_memory &&
- !hugetlb_optimize_vmemmap_enabled() &&
- IS_ENABLED(CONFIG_MHP_MEMMAP_ON_MEMORY) &&
+ return mhp_memmap_on_memory() &&
size == memory_block_size_bytes() &&
IS_ALIGNED(vmemmap_size, PMD_SIZE) &&
IS_ALIGNED(remaining_size, (pageblock_nr_pages << PAGE_SHIFT));
@@ -2076,7 +2096,7 @@ static int __ref try_remove_memory(u64 s
* We only support removing memory added with MHP_MEMMAP_ON_MEMORY in
* the same granularity it was added - a single memory block.
*/
- if (memmap_on_memory) {
+ if (mhp_memmap_on_memory()) {
nr_vmemmap_pages = walk_memory_blocks(start, size, NULL,
get_nr_vmemmap_pages_cb);
if (nr_vmemmap_pages) {
_
Patches currently in -mm which might be from songmuchun@xxxxxxxxxxxxx are
mm-hugetlb_vmemmap-disable-hugetlb_optimize_vmemmap-when-struct-page-crosses-page-boundaries.patch
mm-memory_hotplug-override-memmap_on_memory-when-hugetlb_free_vmemmap=on.patch
mm-hugetlb_vmemmap-use-kstrtobool-for-hugetlb_vmemmap-param-parsing.patch
mm-hugetlb_vmemmap-add-hugetlb_optimize_vmemmap-sysctl.patch
