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Tue, 21 Oct 2025 13:43:37 +0200 (CEST) Date: Tue, 21 Oct 2025 13:43:31 +0200 From: Boris Brezillon To: =?UTF-8?B?TG/Dr2M=?= Molinari Cc: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , Rob Herring , Steven Price , Liviu Dudau , Melissa Wen , =?UTF-8?B?TWHDrXJh?= Canal , Hugh Dickins , Baolin Wang , Andrew Morton , Al Viro , =?UTF-8?B?TWlrb8WCYWo=?= Wasiak , Christian Brauner , Nitin Gote , Andi Shyti , Jonathan Corbet , Christopher Healy , Matthew Wilcox , Bagas Sanjaya , 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: Re: [PATCH v5 05/12] drm/gem: Add huge tmpfs mountpoint helpers Message-ID: <20251021134331.549ebeea@fedora> In-Reply-To: <20251021113049.17242-6-loic.molinari@collabora.com> References: <20251021113049.17242-1-loic.molinari@collabora.com> <20251021113049.17242-6-loic.molinari@collabora.com> Organization: Collabora X-Mailer: Claws Mail 4.3.1 (GTK 3.24.49; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: B24AB140010 X-Rspamd-Server: rspam02 X-Stat-Signature: ty5ii7ndwj1cnezatctjwp438y8eqwnx X-HE-Tag: 1761047020-9406 X-HE-Meta: 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 s5Q== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 21 Oct 2025 13:30:42 +0200 Lo=C3=AFc Molinari 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. >=20 > The next commits will port drivers to this helper. >=20 > v3: > - store huge tmpfs mountpoint in drm_device >=20 > v4: > - return 0 in builds with CONFIG_TRANSPARENT_HUGEPAGE=3Dn > - return 0 when huge_mnt already exists > - use new vfs_parse_fs_string() helper >=20 > 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=3Dn > - compile out drm_device's huge_mnt field in builds with > CONFIG_TRANSPARENT_HUGEPAGE=3Dn > - add drm_gem_has_huge_mnt() helper >=20 > Signed-off-by: Lo=C3=AFc Molinari > --- > drivers/gpu/drm/drm_gem.c | 39 +++++++++++++++++++++++++++++ > include/drm/drm_device.h | 15 +++++++++++ > include/drm/drm_gem.h | 52 +++++++++++++++++++++++++++++++++++++++ > 3 files changed, 106 insertions(+) >=20 > 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 > #include > #include > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE > +#include > +#endif > #include > #include > #include > @@ -82,6 +85,42 @@ > * up at a later date, and as our interface with shmfs for memory alloca= tion. > */ > =20 > +#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 =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..684939987d83 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 > + /** > + * @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,\ > } > =20 > +#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 mountpoi= nt > + * @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 fo= r the > + * lifetime of the DRM device @dev which is used at GEM object initializ= ation > + * with drm_gem_object_init(). > + * > + * The most common option value @value is "within_size" which only alloc= ates > + * huge pages if the page will be fully within the GEM object size. "alw= ays", > + * "advise" and "never" are supported too but the latter would just crea= te 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,