On 3/19/2026 7:35 AM, Jonathan Cameron wrote:
On Thu, 19 Mar 2026 01:15:00 +0000
Smita Koralahalli <[email protected]> wrote:
Reworked from a patch by Alison Schofield <[email protected]>
Reintroduce Soft Reserved range into the iomem_resource tree for HMEM
to consume.
This restores visibility in /proc/iomem for ranges actively in use, while
avoiding the early-boot conflicts that occurred when Soft Reserved was
published into iomem before CXL window and region discovery.
Link:
https://lore.kernel.org/linux-cxl/29312c0765224ae76862d59a17748c8188fb95f1.1692638817.git.alison.schofi...@intel.com/
Co-developed-by: Alison Schofield <[email protected]>
Signed-off-by: Alison Schofield <[email protected]>
Co-developed-by: Zhijian Li <[email protected]>
Signed-off-by: Zhijian Li <[email protected]>
Signed-off-by: Smita Koralahalli <[email protected]>
Reviewed-by: Dave Jiang <[email protected]>
Reviewed-by: Jonathan Cameron <[email protected]>
Reviewed-by: Dan Williams <[email protected]>
One minor update needed as kmalloc_obj() has shown up in meantime.
Thanks
Jonathan
---
drivers/dax/hmem/hmem.c | 32 +++++++++++++++++++++++++++++++-
1 file changed, 31 insertions(+), 1 deletion(-)
diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
index 8c574123bd3b..15e462589b92 100644
--- a/drivers/dax/hmem/hmem.c
+++ b/drivers/dax/hmem/hmem.c
@@ -72,6 +72,34 @@ void dax_hmem_flush_work(void)
}
EXPORT_SYMBOL_GPL(dax_hmem_flush_work);
+static void remove_soft_reserved(void *r)
+{
+ remove_resource(r);
+ kfree(r);
+}
+
+static int add_soft_reserve_into_iomem(struct device *host,
+ const struct resource *res)
+{
+ int rc;
+
+ struct resource *soft __free(kfree) =
+ kmalloc(sizeof(*res), GFP_KERNEL);
Update to
struct resource *soft __free(kfree) = kmalloc_obj(*soft);
Got added in 7.0 with lots of call sites updated via scripting.
Not sure why this had sizeof(*res) rather than sizeof(*soft).
Same type but should have been soft! If nothing else that would
probably have broken the scripts looking for where we should
be using kmalloc_obj().
Okay I will update it. sizeof(*res) was a typo from my end. Sorry.
Will change to kmalloc_obj().
Thanks
Smita
+ if (!soft)
+ return -ENOMEM;
+
+ *soft = DEFINE_RES_NAMED_DESC(res->start, (res->end - res->start + 1),
+ "Soft Reserved", IORESOURCE_MEM,
+ IORES_DESC_SOFT_RESERVED);
+
+ rc = insert_resource(&iomem_resource, soft);
+ if (rc)
+ return rc;
+
+ return devm_add_action_or_reset(host, remove_soft_reserved,
+ no_free_ptr(soft));
+}
+
static int hmem_register_device(struct device *host, int target_nid,
const struct resource *res)
{
@@ -94,7 +122,9 @@ static int hmem_register_device(struct device *host, int
target_nid,
if (rc != REGION_INTERSECTS)
return 0;
- /* TODO: Add Soft-Reserved memory back to iomem */
+ rc = add_soft_reserve_into_iomem(host, res);
+ if (rc)
+ return rc;
id = memregion_alloc(GFP_KERNEL);
if (id < 0) {
