On Tue, 21 Oct 2025 13:30:42 +0200 Loïc Molinari <[email protected]> wrote:
> Add the drm_gem_huge_mnt_create() and drm_gem_has_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 checks whether a dedicated huge tmpfs > mountpoint is in use by a DRM device. > > The next commits will port drivers to this helper. > > 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: > - removed 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 > > Signed-off-by: Loïc Molinari <[email protected]> > --- > drivers/gpu/drm/drm_gem.c | 39 +++++++++++++++++++++++++++++ > include/drm/drm_device.h | 15 +++++++++++ > include/drm/drm_gem.h | 52 +++++++++++++++++++++++++++++++++++++++ > 3 files changed, 106 insertions(+) > > diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c > index a98d5744cc6c..161da048330e 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 +85,42 @@ > * 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); > +} > + > +int __drm_gem_huge_mnt_create(struct drm_device *dev, const char *value) > +{ > + struct file_system_type *type; > + struct fs_context *fc; > + int ret; > + > + if (unlikely(drm_gem_has_huge_mnt(dev))) > + return 0; > + > + type = get_fs_type("tmpfs"); > + if (unlikely(!type)) > + return -EOPNOTSUPP; > + fc = fs_context_for_mount(type, SB_KERNMOUNT); > + if (IS_ERR(fc)) > + return PTR_ERR(fc); > + ret = vfs_parse_fs_string(fc, "source", "tmpfs"); > + if (unlikely(ret)) > + return -ENOPARAM; > + ret = vfs_parse_fs_string(fc, "huge", value); > + if (unlikely(ret)) > + return -ENOPARAM; > + > + dev->huge_mnt = fc_mount_longterm(fc); > + put_fs_context(fc); > + > + return drmm_add_action_or_reset(dev, drm_gem_huge_mnt_free, NULL); > +} > +EXPORT_SYMBOL_GPL(__drm_gem_huge_mnt_create); > +#endif > + > static void > drm_gem_init_release(struct drm_device *dev, void *ptr) > { > diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h > index 778b2cca6c49..684939987d83 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; > > + /** > + * @huge_mnt: > + * > + * Huge tmpfs mountpoint used at GEM object initialization > + * drm_gem_object_init(). Drivers can call drm_gem_huge_mnt_create() to > + * create a huge tmfps mountpoint. The default tmpfs mountpoint > + * (`shm_mnt`) is used if NULL. > + */ > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE Can we move the ifdef before the kernel doc for this field? > + 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..9845854850fb 100644 > --- a/include/drm/drm_gem.h > +++ b/include/drm/drm_gem.h > @@ -492,6 +492,58 @@ struct drm_gem_object { > DRM_GEM_FOPS,\ > } > > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE > +int __drm_gem_huge_mnt_create(struct drm_device *dev, const char *value); > +#endif > + > +/** > + * drm_gem_huge_mnt_create - Create, mount and use a huge tmpfs mountpoint > + * @dev: DRM device a huge tmpfs mountpoint should be used with > + * @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 > + * 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. > + */ > +static inline int drm_gem_huge_mnt_create(struct drm_device *dev, > + const char *value) > +{ > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE > + return __drm_gem_huge_mnt_create(dev, value); > +#else > + return 0; > +#endif > +} Unless __drm_gem_huge_mnt_create() is really used internally (at first glance, that doesn't seem to be the case), I'd suggest renaming it drm_gem_huge_mnt_create() and having: #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_has_huge_mnt - Check if a huge tmpfs mountpoint is in use > + * @dev: DRM device > + * > + * This function checks whether a huge tmpfs mountpoint is in use after by > DRM > + * device @dev. A huge tmpfs mountpoint is used after a successful call to > + * drm_gem_huge_mnt_create() on builds with Transparent Hugepage enabled. > + * > + * Returns: > + * true on success, false otherwise. > + */ > +static inline bool drm_gem_has_huge_mnt(struct drm_device *dev) > +{ > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE > + return !!dev->huge_mnt; > +#else > + return false; > +#endif > +} > + > void drm_gem_object_release(struct drm_gem_object *obj); > void drm_gem_object_free(struct kref *kref); > int drm_gem_object_init(struct drm_device *dev,
