From: Vishal Verma
With DAX memory regions originating from CXL memory expanders or
NVDIMMs, the kmem driver may be hot-adding huge amounts of system memory
on a system without enough 'regular' main memory to support the memmap
for it. To avoid this, ensure that all kmem managed hotplugged memory is
added with the MHP_MEMMAP_ON_MEMORY flag to place the memmap on the
new memory region being hot added.
To do this, call add_memory() in chunks of memory_block_size_bytes() as
that is a requirement for memmap_on_memory.
Cc: "Rafael J. Wysocki"
Cc: Len Brown
Cc: Andrew Morton
Cc: David Hildenbrand
Cc: Oscar Salvador
Cc: Dan Williams
Cc: Dave Jiang
Cc: Dave Hansen
Cc: Huang Ying
Signed-off-by: Vishal Verma
Signed-off-by: Aneesh Kumar K.V
---
drivers/dax/kmem.c | 81 +-
1 file changed, 59 insertions(+), 22 deletions(-)
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index 898ca9505754..840bf7b40a44 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -12,6 +12,7 @@
#include
#include
#include
+#include
#include "dax-private.h"
#include "bus.h"
@@ -105,6 +106,7 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
data->mgid = rc;
for (i = 0; i < dev_dax->nr_range; i++) {
+ u64 cur_start, cur_len, remaining;
struct resource *res;
struct range range;
@@ -137,21 +139,42 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
res->flags = IORESOURCE_SYSTEM_RAM;
/*
-* Ensure that future kexec'd kernels will not treat
-* this as RAM automatically.
+* Add memory in chunks of memory_block_size_bytes() so that
+* it is considered for MHP_MEMMAP_ON_MEMORY
+* @range has already been aligned to memory_block_size_bytes(),
+* so the following loop will always break it down cleanly.
*/
- rc = add_memory_driver_managed(data->mgid, range.start,
- range_len(), kmem_name, MHP_NID_IS_MGID);
-
- if (rc) {
- dev_warn(dev, "mapping%d: %#llx-%#llx memory add
failed\n",
- i, range.start, range.end);
- remove_resource(res);
- kfree(res);
- data->res[i] = NULL;
- if (mapped)
- continue;
- goto err_request_mem;
+ cur_start = range.start;
+ cur_len = memory_block_size_bytes();
+ remaining = range_len();
+ while (remaining) {
+ /*
+* If alignment rules are not satisified we will
+* fallback normal memmap allocation.
+*/
+ mhp_t mhp_flags = MHP_NID_IS_MGID |
MHP_MEMMAP_ON_MEMORY;
+ /*
+* Ensure that future kexec'd kernels will not treat
+* this as RAM automatically.
+*/
+ rc = add_memory_driver_managed(data->mgid, cur_start,
+ cur_len, kmem_name,
+ mhp_flags);
+
+ if (rc) {
+ dev_warn(dev,
+"mapping%d: %#llx-%#llx memory add
failed\n",
+i, cur_start, cur_start + cur_len - 1);
+ remove_resource(res);
+ kfree(res);
+ data->res[i] = NULL;
+ if (mapped)
+ continue;
+ goto err_request_mem;
+ }
+
+ cur_start += cur_len;
+ remaining -= cur_len;
}
mapped++;
}
@@ -186,25 +209,39 @@ static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
* unbind will succeed even if we return failure.
*/
for (i = 0; i < dev_dax->nr_range; i++) {
+
+ u64 cur_start, cur_len, remaining;
struct range range;
+ bool resource_remove;
int rc;
rc = dax_kmem_range(dev_dax, i, );
if (rc)
continue;
- rc = remove_memory(range.start, range_len());
- if (rc == 0) {
+ resource_remove = true;
+ cur_start = range.start;
+ cur_len = memory_block_size_bytes();
+ remaining = range_len();
+ while (remaining) {
+
+ rc = remove_memory(cur_start, cur_len);
+
