Hi Loïc,
On 28/11/25 15:52, Loïc Molinari wrote:
Add the drm_gem_huge_mnt_create() and drm_gem_get_huge_mnt() helpers
to avoid code duplication in the i915, V3D, Panfrost and Panthor
drivers. The former creates and mounts a dedicated huge tmpfs
mountpoint, for the lifetime of a DRM device, used at GEM object
initialization. The latter retrieves the dedicated huge tmpfs
mountpoint used by a DRM device.
The next commits will port drivers to these helpers.
v3:
- store huge tmpfs mountpoint in drm_device
v4:
- return 0 in builds with CONFIG_TRANSPARENT_HUGEPAGE=n
- return 0 when huge_mnt already exists
- use new vfs_parse_fs_string() helper
v5:
- remove warning on !dev->huge_mnt and reset to NULL on free
- inline drm_gem_huge_mnt_create() to remove func from text and avoid
calls in builds with CONFIG_TRANSPARENT_HUGEPAGE=n
- compile out drm_device's huge_mnt field in builds with
CONFIG_TRANSPARENT_HUGEPAGE=n
- add drm_gem_has_huge_mnt() helper
v6:
- move huge_mnt doc into ifdef'd section
- either inline or export drm_gem_huge_mnt_create()
v7:
- include <drm/drm_device.h> in drm_gem.h
v9:
- replace drm_gem_has_huge_mnt() by drm_gem_get_huge_mnt()
Signed-off-by: Loïc Molinari <[email protected]>
Reviewed-by: Maíra Canal <[email protected]>
Some suggestions below (feel free to ignore):
---
drivers/gpu/drm/drm_gem.c | 57 +++++++++++++++++++++++++++++++++++++++
include/drm/drm_device.h | 15 +++++++++++
include/drm/drm_gem.h | 33 +++++++++++++++++++++++
3 files changed, 105 insertions(+)
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 41d344c270a7..94e5e04865ba 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -29,6 +29,9 @@
#include <linux/export.h>
#include <linux/file.h>
#include <linux/fs.h>
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#include <linux/fs_context.h>
+#endif
#include <linux/iosys-map.h>
#include <linux/mem_encrypt.h>
#include <linux/mm.h>
@@ -82,6 +85,60 @@
* up at a later date, and as our interface with shmfs for memory allocation.
*/
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static void drm_gem_huge_mnt_free(struct drm_device *dev, void *data)
+{
+ kern_unmount(dev->huge_mnt);
+}
+
+/**
+ * drm_gem_huge_mnt_create - Create, mount and use a huge tmpfs mountpoint
+ * @dev: DRM device a huge tmpfs mountpoint should be used with
Suggestion: "DRM device that will use the huge tmpfs mountpoint"
+ * @value: huge tmpfs mount option value
+ *
+ * This function creates and mounts a dedicated huge tmpfs mountpoint for the
+ * lifetime of the DRM device @dev which is used at GEM object initialization
+ * with drm_gem_object_init().
+ *
+ * The most common option value @value is "within_size" which only allocates
Suggestion: "The most common option for @value is..."
+ * huge pages if the page will be fully within the GEM object size. "always",
+ * "advise" and "never" are supported too but the latter would just create a
+ * mountpoint similar to the default one (`shm_mnt`). See shmemfs and
+ * Transparent Hugepage for more information.
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
[...]
diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
index 5af49c5c3778..7dc560ad14fc 100644
--- a/include/drm/drm_device.h
+++ b/include/drm/drm_device.h
@@ -3,6 +3,9 @@
#include <linux/list.h>
#include <linux/kref.h>
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#include <linux/mount.h>
+#endif
#include <linux/mutex.h>
#include <linux/idr.h>
#include <linux/sched.h>
@@ -168,6 +171,18 @@ struct drm_device {
*/
struct drm_master *master;
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ /**
+ * @huge_mnt:
+ *
+ * Huge tmpfs mountpoint used at GEM object initialization
+ * drm_gem_object_init(). Drivers can call drm_gem_huge_mnt_create() to
Suggestion: "Drivers can call drm_gem_huge_mnt_create() to mount and use
it."
+ * create a huge tmfps mountpoint. The default tmpfs mountpoint
+ * (`shm_mnt`) is used if NULL.
+ */
+ struct vfsmount *huge_mnt;
+#endif
+
/**
* @driver_features: per-device driver features
*
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
index 7c8bd67d087c..4e9ab5d294ac 100644
--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -40,6 +40,9 @@
#include <linux/list.h>
#include <linux/mutex.h>
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#include <drm/drm_device.h>
+#endif
#include <drm/drm_vma_manager.h>
struct iosys_map;
@@ -492,6 +495,36 @@ struct drm_gem_object {
DRM_GEM_FOPS,\
}
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+int drm_gem_huge_mnt_create(struct drm_device *dev, const char *value);
+#else
+static inline int drm_gem_huge_mnt_create(struct drm_device *dev,
+ const char *value)
+{
+ return 0;
+}
+#endif
+
+/**
+ * drm_gem_get_huge_mnt - Get the huge tmpfs mountpoint used by a DRM device
+ * @dev: DRM device
+
+ * This function gets the huge tmpfs mountpoint used by DRM device @dev. A huge
+ * tmpfs mountpoint is used after a successful call to
drm_gem_huge_mnt_create()
Suggestion: "A huge tmpfs is used instead of `shm_mnt` after a
successful call to drm_gem_huge_mnt_create() when
CONFIG_TRANSPARENT_HUGEPAGE is enabled"
Best Regards,
- Maíra
