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(unknown [IPv6:2a01:e0a:5e3:6100:826d:bc07:e98c:84a]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: loicmolinari) by bali.collaboradmins.com (Postfix) with ESMTPSA id 1CA5817E130A; Mon, 10 Nov 2025 16:50:10 +0100 (CET) From: =?UTF-8?q?Lo=C3=AFc=20Molinari?= To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , Boris Brezillon , Rob Herring , Steven Price , Liviu Dudau , Melissa Wen , =?UTF-8?q?Ma=C3=ADra=20Canal?= , Hugh Dickins , Baolin Wang , Andrew Morton , =?UTF-8?q?Lo=C3=AFc=20Molinari?= , Al Viro , =?UTF-8?q?Miko=C5=82aj=20Wasiak?= , Christian Brauner , Nitin Gote , Andi Shyti , Jonathan Corbet , Christopher Healy , Matthew Wilcox , Bagas Sanjaya Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, kernel@collabora.com Subject: [PATCH v7 04/11] drm/gem: Add huge tmpfs mountpoint helpers Date: Mon, 10 Nov 2025 16:49:52 +0100 Message-ID: <20251110155000.2936-5-loic.molinari@collabora.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251110155000.2936-1-loic.molinari@collabora.com> References: <20251110155000.2936-1-loic.molinari@collabora.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable 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=3Dn - 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=3Dn - compile out drm_device's huge_mnt field in builds with CONFIG_TRANSPARENT_HUGEPAGE=3Dn - 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 in drm_gem.h Signed-off-by: Lo=C3=AFc Molinari --- 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 2a0eecc0d3e4..bbca2ab9e9a5 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -29,6 +29,9 @@ #include #include #include +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#include +#endif #include #include #include @@ -82,6 +85,60 @@ * up at a later date, and as our interface with shmfs for memory allocati= on. */ =20 +#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 + * @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 initializat= ion + * with drm_gem_object_init(). + * + * The most common option value @value is "within_size" which only allocat= es + * huge pages if the page will be fully within the GEM object size. "alway= s", + * "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. + */ +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 =3D get_fs_type("tmpfs"); + if (unlikely(!type)) + return -EOPNOTSUPP; + fc =3D fs_context_for_mount(type, SB_KERNMOUNT); + if (IS_ERR(fc)) + return PTR_ERR(fc); + ret =3D vfs_parse_fs_string(fc, "source", "tmpfs"); + if (unlikely(ret)) + return -ENOPARAM; + ret =3D vfs_parse_fs_string(fc, "huge", value); + if (unlikely(ret)) + return -ENOPARAM; + + dev->huge_mnt =3D 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..bcde07c43e3f 100644 --- a/include/drm/drm_device.h +++ b/include/drm/drm_device.h @@ -3,6 +3,9 @@ =20 #include #include +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#include +#endif #include #include #include @@ -168,6 +171,18 @@ struct drm_device { */ struct drm_master *master; =20 +#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 + * 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..58fa1e6b9773 100644 --- a/include/drm/drm_gem.h +++ b/include/drm/drm_gem.h @@ -40,6 +40,9 @@ #include #include =20 +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#include +#endif #include =20 struct iosys_map; @@ -492,6 +495,36 @@ struct drm_gem_object { DRM_GEM_FOPS,\ } =20 +#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, --=20 2.47.3