On 20/10/2025 11:33, Tvrtko Ursulin wrote:

On 15/10/2025 16:30, Loïc Molinari wrote:
Make use of the new drm_gem_huge_mnt_create() helper to avoid code
duplication. Now that it's just a few lines long, the single function
in v3d_gemfs.c is moved into v3d_gem.c.

v3:
- use huge tmpfs mountpoint in drm_device
- move v3d_gemfs.c into v3d_gem.c

v4:
- clean up mountpoint creation error handling

Signed-off-by: Loïc Molinari <[email protected]>
---
  drivers/gpu/drm/v3d/Makefile    |  3 +-
  drivers/gpu/drm/v3d/v3d_bo.c    |  5 ++-
  drivers/gpu/drm/v3d/v3d_drv.c   |  2 +-
  drivers/gpu/drm/v3d/v3d_drv.h   | 11 +-----
  drivers/gpu/drm/v3d/v3d_gem.c   | 27 +++++++++++++--
  drivers/gpu/drm/v3d/v3d_gemfs.c | 60 ---------------------------------
  6 files changed, 30 insertions(+), 78 deletions(-)
  delete mode 100644 drivers/gpu/drm/v3d/v3d_gemfs.c

diff --git a/drivers/gpu/drm/v3d/Makefile b/drivers/gpu/drm/v3d/Makefile
index fcf710926057..b7d673f1153b 100644
--- a/drivers/gpu/drm/v3d/Makefile
+++ b/drivers/gpu/drm/v3d/Makefile
@@ -13,8 +13,7 @@ v3d-y := \
      v3d_trace_points.o \
      v3d_sched.o \
      v3d_sysfs.o \
-    v3d_submit.o \
-    v3d_gemfs.o
+    v3d_submit.o
  v3d-$(CONFIG_DEBUG_FS) += v3d_debugfs.o
diff --git a/drivers/gpu/drm/v3d/v3d_bo.c b/drivers/gpu/drm/v3d/v3d_bo.c
index c41476ddde68..6b9909bfce82 100644
--- a/drivers/gpu/drm/v3d/v3d_bo.c
+++ b/drivers/gpu/drm/v3d/v3d_bo.c
@@ -112,7 +112,7 @@ v3d_bo_create_finish(struct drm_gem_object *obj)
      if (IS_ERR(sgt))
          return PTR_ERR(sgt);
-    if (!v3d->gemfs)
+    if (!obj->dev->huge_mnt)

Maybe it would be a good idea to add a helper for this check. Keeping aligned with drm_gem_huge_mnt_create() something like drm_gem_has_huge_mnt()? That would then hide the optional drm_device struct member if you decide to go for that.

Sounds good. This would prevent cluttering code with ifdefs in drivers while still removing the huge_mnt field in drm_device in builds with CONFIG_TRANSPARENT_HUGEPAGE=n. I'll propose a new version doing so.


          align = SZ_4K;
      else if (obj->size >= SZ_1M)
          align = SZ_1M;
@@ -148,12 +148,11 @@ struct v3d_bo *v3d_bo_create(struct drm_device *dev, struct drm_file *file_priv,
                   size_t unaligned_size)
  {
      struct drm_gem_shmem_object *shmem_obj;
-    struct v3d_dev *v3d = to_v3d_dev(dev);
      struct v3d_bo *bo;
      int ret;
      shmem_obj = drm_gem_shmem_create_with_mnt(dev, unaligned_size,
-                          v3d->gemfs);
+                          dev->huge_mnt);

Okay this one goes away by the end of the series.

      if (IS_ERR(shmem_obj))
          return ERR_CAST(shmem_obj);
      bo = to_v3d_bo(&shmem_obj->base);
diff --git a/drivers/gpu/drm/v3d/v3d_drv.c b/drivers/gpu/drm/v3d/ v3d_drv.c
index c5a3bbbc74c5..19ec0ea7f38e 100644
--- a/drivers/gpu/drm/v3d/v3d_drv.c
+++ b/drivers/gpu/drm/v3d/v3d_drv.c
@@ -106,7 +106,7 @@ static int v3d_get_param_ioctl(struct drm_device *dev, void *data,
          args->value = v3d->perfmon_info.max_counters;
          return 0;
      case DRM_V3D_PARAM_SUPPORTS_SUPER_PAGES:
-        args->value = !!v3d->gemfs;
+        args->value = !!dev->huge_mnt;
          return 0;
      case DRM_V3D_PARAM_GLOBAL_RESET_COUNTER:
          mutex_lock(&v3d->reset_lock);
diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/ v3d_drv.h
index 1884686985b8..99a39329bb85 100644
--- a/drivers/gpu/drm/v3d/v3d_drv.h
+++ b/drivers/gpu/drm/v3d/v3d_drv.h
@@ -158,11 +158,6 @@ struct v3d_dev {
      struct drm_mm mm;
      spinlock_t mm_lock;
-    /*
-     * tmpfs instance used for shmem backed objects
-     */
-    struct vfsmount *gemfs;
-
      struct work_struct overflow_mem_work;
      struct v3d_queue_state queue[V3D_MAX_QUEUES];
@@ -569,6 +564,7 @@ extern const struct dma_fence_ops v3d_fence_ops;
  struct dma_fence *v3d_fence_create(struct v3d_dev *v3d, enum v3d_queue q);
  /* v3d_gem.c */
+extern bool super_pages;
  int v3d_gem_init(struct drm_device *dev);
  void v3d_gem_destroy(struct drm_device *dev);
  void v3d_reset_sms(struct v3d_dev *v3d);
@@ -576,11 +572,6 @@ void v3d_reset(struct v3d_dev *v3d);
  void v3d_invalidate_caches(struct v3d_dev *v3d);
  void v3d_clean_caches(struct v3d_dev *v3d);
-/* v3d_gemfs.c */
-extern bool super_pages;
-void v3d_gemfs_init(struct v3d_dev *v3d);
-void v3d_gemfs_fini(struct v3d_dev *v3d);
-
  /* v3d_submit.c */
  void v3d_job_cleanup(struct v3d_job *job);
  void v3d_job_put(struct v3d_job *job);
diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/ v3d_gem.c
index bb110d35f749..635ff0fabe7e 100644
--- a/drivers/gpu/drm/v3d/v3d_gem.c
+++ b/drivers/gpu/drm/v3d/v3d_gem.c
@@ -258,6 +258,30 @@ v3d_invalidate_caches(struct v3d_dev *v3d)
      v3d_invalidate_slices(v3d, 0);
  }
+static void
+v3d_huge_mnt_init(struct v3d_dev *v3d)
+{
+    int err = 0;
+
+    /*
+     * By using a huge shmemfs mountpoint when the user wants to
+     * enable Super Pages, we can pass in mount flags that better
+     * match our usecase.
+     */
+
+    if (super_pages)
+        err = drm_gem_huge_mnt_create(&v3d->drm, "within_size");

If it is this patch that is creating the build failure then the two should be squashed.

Then in "drm/v3d: Fix builds with CONFIG_TRANSPARENT_HUGEPAGE=n" this ends up a bit ugly:

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
      if (super_pages)
#endif
          err = drm_gem_huge_mnt_create(&v3d->drm, "within_size");

Does this not work:

      if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && super_pages)
          err = drm_gem_huge_mnt_create(&v3d->drm, "within_size");

?

I've got a new version ready that does exactly that (after discussing with Boris).


Regards,

Tvrtko

+
+    if (v3d->drm.huge_mnt)
+        drm_info(&v3d->drm, "Using Transparent Hugepages\n");
+    else if (err)
+        drm_warn(&v3d->drm, "Can't use Transparent Hugepages (%d)\n",
+             err);
+    else
+        drm_notice(&v3d->drm,
+               "Transparent Hugepage support is recommended for optimal performance on this platform!\n");
+}
+
  int
  v3d_gem_init(struct drm_device *dev)
  {
@@ -309,7 +333,7 @@ v3d_gem_init(struct drm_device *dev)
      v3d_init_hw_state(v3d);
      v3d_mmu_set_page_table(v3d);
-    v3d_gemfs_init(v3d);
+    v3d_huge_mnt_init(v3d);
      ret = v3d_sched_init(v3d);
      if (ret) {
@@ -329,7 +353,6 @@ v3d_gem_destroy(struct drm_device *dev)
      enum v3d_queue q;
      v3d_sched_fini(v3d);
-    v3d_gemfs_fini(v3d);
      /* Waiting for jobs to finish would need to be done before
       * unregistering V3D.
diff --git a/drivers/gpu/drm/v3d/v3d_gemfs.c b/drivers/gpu/drm/v3d/ v3d_gemfs.c
deleted file mode 100644
index c1a30166c099..000000000000
--- a/drivers/gpu/drm/v3d/v3d_gemfs.c
+++ /dev/null
@@ -1,60 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0+
-/* Copyright (C) 2024 Raspberry Pi */
-
-#include <linux/fs.h>
-#include <linux/mount.h>
-#include <linux/fs_context.h>
-
-#include "v3d_drv.h"
-
-void v3d_gemfs_init(struct v3d_dev *v3d)
-{
-    struct file_system_type *type;
-    struct fs_context *fc;
-    struct vfsmount *gemfs;
-    int ret;
-
-    /*
-     * By creating our own shmemfs mountpoint, we can pass in
-     * mount flags that better match our usecase. However, we
-     * only do so on platforms which benefit from it.
-     */
-    if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
-        goto err;
-
-    /* The user doesn't want to enable Super Pages */
-    if (!super_pages)
-        goto err;
-
-    type = get_fs_type("tmpfs");
-    if (!type)
-        goto err;
-
-    fc = fs_context_for_mount(type, SB_KERNMOUNT);
-    if (IS_ERR(fc))
-        goto err;
-    ret = vfs_parse_fs_string(fc, "source", "tmpfs");
-    if (!ret)
-        ret = vfs_parse_fs_string(fc, "huge", "within_size");
-    if (!ret)
-        gemfs = fc_mount_longterm(fc);
-    put_fs_context(fc);
-    if (ret)
-        goto err;
-
-    v3d->gemfs = gemfs;
-    drm_info(&v3d->drm, "Using Transparent Hugepages\n");
-
-    return;
-
-err:
-    v3d->gemfs = NULL;
-    drm_notice(&v3d->drm,
-           "Transparent Hugepage support is recommended for optimal performance on this platform!\n");
-}
-
-void v3d_gemfs_fini(struct v3d_dev *v3d)
-{
-    if (v3d->gemfs)
-        kern_unmount(v3d->gemfs);
-}


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