[PATCH v5 06/12] drm/i915: Use huge tmpfs mountpoint helpers

Loïc Molinari
2025-10-21T11:31:03Z

Make use of the new drm_gem_huge_mnt_create() and
drm_gem_has_huge_mnt() helpers to avoid code duplication. Now that
it's just a few lines long, the single function in i915_gemfs.c is
moved into v3d_gem_shmem.c.

v3:
- use huge tmpfs mountpoint in drm_device
- move i915_gemfs.c into i915_gem_shmem.c

v4:
- clean up mountpoint creation error handling

v5:
- Use drm_gem_has_huge_mnt() helper

Signed-off-by: Loïc Molinari <loic.molinari@collabora.com>
---
drivers/gpu/drm/i915/Makefile | 3 +-
drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 47 +++++++++----
drivers/gpu/drm/i915/gem/i915_gemfs.c | 69 -------------------
drivers/gpu/drm/i915/gem/i915_gemfs.h | 14 ----
.../gpu/drm/i915/gem/selftests/huge_pages.c | 11 +--
drivers/gpu/drm/i915/i915_drv.h | 5 --
6 files changed, 41 insertions(+), 108 deletions(-)
delete mode 100644 drivers/gpu/drm/i915/gem/i915_gemfs.c
delete mode 100644 drivers/gpu/drm/i915/gem/i915_gemfs.h

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index e58c0c158b3a..e22393a7cf6f 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -163,8 +163,7 @@ gem-y += \
gem/i915_gem_ttm_move.o \
gem/i915_gem_ttm_pm.o \
gem/i915_gem_userptr.o \
- gem/i915_gem_wait.o \
- gem/i915_gemfs.o
+ gem/i915_gem_wait.o
i915-y += \
$(gem-y) \
i915_active.o \
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
index b9dae15c1d16..944aceac4cd3 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
@@ -9,14 +9,15 @@
#include <linux/uio.h>

#include <drm/drm_cache.h>
+#include <drm/drm_gem.h>

#include "gem/i915_gem_region.h"
#include "i915_drv.h"
#include "i915_gem_object.h"
#include "i915_gem_tiling.h"
-#include "i915_gemfs.h"
#include "i915_scatterlist.h"
#include "i915_trace.h"
+#include "i915_utils.h"

/*
* Move folios to appropriate lru and release the batch, decrementing the
@@ -506,9 +507,9 @@ static int __create_shmem(struct drm_i915_private *i915,
if (BITS_PER_LONG == 64 && size > MAX_LFS_FILESIZE)
return -E2BIG;

- if (i915->mm.gemfs)
- filp = shmem_file_setup_with_mnt(i915->mm.gemfs, "i915", size,
- flags);
+ if (drm_gem_has_huge_mnt(&i915->drm))
+ filp = shmem_file_setup_with_mnt(i915->drm.huge_mnt, "i915",
+ size, flags);
else
filp = shmem_file_setup("i915", size, flags);
if (IS_ERR(filp))
@@ -635,21 +636,41 @@ i915_gem_object_create_shmem_from_data(struct drm_i915_private *i915,

static int init_shmem(struct intel_memory_region *mem)
{
- i915_gemfs_init(mem->i915);
- intel_memory_region_set_name(mem, "system");
+ struct drm_i915_private *i915 = mem->i915;
+ int err;

- return 0; /* We have fallback to the kernel mnt if gemfs init failed. */
-}
+ /*
+ * By creating our own shmemfs mountpoint, we can pass in
+ * mount flags that better match our usecase.
+ *
+ * One example, although it is probably better with a per-file
+ * control, is selecting huge page allocations ("huge=within_size").
+ * However, we only do so on platforms which benefit from it, or to
+ * offset the overhead of iommu lookups, where with latter it is a net
+ * win even on platforms which would otherwise see some performance
+ * regressions such a slow reads issue on Broadwell and Skylake.
+ */

-static int release_shmem(struct intel_memory_region *mem)
-{
- i915_gemfs_fini(mem->i915);
- return 0;
+ if (GRAPHICS_VER(i915) < 11 && !i915_vtd_active(i915))
+ goto no_thp;
+
+ err = drm_gem_huge_mnt_create(&i915->drm, "within_size");
+ if (drm_gem_has_huge_mnt(&i915->drm))
+ drm_info(&i915->drm, "Using Transparent Hugepages\n");
+ else if (err)
+ drm_notice(&i915->drm,
+ "Transparent Hugepage support is recommended for optimal performance%s\n",
+ GRAPHICS_VER(i915) >= 11 ? " on this platform!" :
+ " when IOMMU is enabled!");
+
+ no_thp:
+ intel_memory_region_set_name(mem, "system");
+
+ return 0; /* We have fallback to the kernel mnt if huge mnt failed. */
}

static const struct intel_memory_region_ops shmem_region_ops = {
.init = init_shmem,
- .release = release_shmem,
.init_object = shmem_object_init,
};

diff --git a/drivers/gpu/drm/i915/gem/i915_gemfs.c b/drivers/gpu/drm/i915/gem/i915_gemfs.c
deleted file mode 100644
index 8f13ec4ff0d0..000000000000
--- a/drivers/gpu/drm/i915/gem/i915_gemfs.c
+++ /dev/null
@@ -1,69 +0,0 @@
-// SPDX-License-Identifier: MIT
-/*
- * Copyright © 2017 Intel Corporation
- */
-
-#include <linux/fs.h>
-#include <linux/mount.h>
-#include <linux/fs_context.h>
-
-#include "i915_drv.h"
-#include "i915_gemfs.h"
-#include "i915_utils.h"
-
-void i915_gemfs_init(struct drm_i915_private *i915)
-{
- 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.
- *
- * One example, although it is probably better with a per-file
- * control, is selecting huge page allocations ("huge=within_size").
- * However, we only do so on platforms which benefit from it, or to
- * offset the overhead of iommu lookups, where with latter it is a net
- * win even on platforms which would otherwise see some performance
- * regressions such a slow reads issue on Broadwell and Skylake.
- */
-
- if (GRAPHICS_VER(i915) < 11 && !i915_vtd_active(i915))
- return;
-
- if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
- 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;
-
- i915->mm.gemfs = gemfs;
- drm_info(&i915->drm, "Using Transparent Hugepages\n");
- return;
-
-err:
- drm_notice(&i915->drm,
- "Transparent Hugepage support is recommended for optimal performance%s\n",
- GRAPHICS_VER(i915) >= 11 ? " on this platform!" :
- " when IOMMU is enabled!");
-}
-
-void i915_gemfs_fini(struct drm_i915_private *i915)
-{
- kern_unmount(i915->mm.gemfs);
-}
diff --git a/drivers/gpu/drm/i915/gem/i915_gemfs.h b/drivers/gpu/drm/i915/gem/i915_gemfs.h
deleted file mode 100644
index 16d4333c9a4e..000000000000
--- a/drivers/gpu/drm/i915/gem/i915_gemfs.h
+++ /dev/null
@@ -1,14 +0,0 @@
-/* SPDX-License-Identifier: MIT */
-/*
- * Copyright © 2017 Intel Corporation
- */
-
-#ifndef __I915_GEMFS_H__
-#define __I915_GEMFS_H__
-
-struct drm_i915_private;
-
-void i915_gemfs_init(struct drm_i915_private *i915);
-void i915_gemfs_fini(struct drm_i915_private *i915);
-
-#endif
diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
index bd08605a1611..2b9f7d86b46e 100644
--- a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
+++ b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
@@ -1316,7 +1316,7 @@ typedef struct drm_i915_gem_object *

static inline bool igt_can_allocate_thp(struct drm_i915_private *i915)
{
- return i915->mm.gemfs && has_transparent_hugepage();
+ return drm_gem_has_huge_mnt(&i915->drm);
}

static struct drm_i915_gem_object *
@@ -1761,7 +1761,8 @@ static int igt_tmpfs_fallback(void *arg)
struct drm_i915_private *i915 = arg;
struct i915_address_space *vm;
struct i915_gem_context *ctx;
- struct vfsmount *gemfs = i915->mm.gemfs;
+ struct vfsmount *huge_mnt =
+ drm_gem_has_huge_mnt(&i915->drm) ? i915->drm.huge_mnt : NULL;
struct drm_i915_gem_object *obj;
struct i915_vma *vma;
struct file *file;
@@ -1782,10 +1783,10 @@ static int igt_tmpfs_fallback(void *arg)
/*
* Make sure that we don't burst into a ball of flames upon falling back
* to tmpfs, which we rely on if on the off-chance we encounter a failure
- * when setting up gemfs.
+ * when setting up a huge mountpoint.
*/

- i915->mm.gemfs = NULL;
+ i915->drm.huge_mnt = NULL;

obj = i915_gem_object_create_shmem(i915, PAGE_SIZE);
if (IS_ERR(obj)) {
@@ -1819,7 +1820,7 @@ static int igt_tmpfs_fallback(void *arg)
out_put:
i915_gem_object_put(obj);
out_restore:
- i915->mm.gemfs = gemfs;
+ i915->drm.huge_mnt = huge_mnt;

i915_vm_put(vm);
out:
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 6a768aad8edd..1bfee23e64a3 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -141,11 +141,6 @@ struct i915_gem_mm {
*/
atomic_t free_count;

- /**
- * tmpfs instance used for shmem backed objects
- */
- struct vfsmount *gemfs;
-
struct intel_memory_region *regions[INTEL_REGION_UNKNOWN];

struct notifier_block oom_notifier;
--
2.47.3