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Mon, 6 Oct 2025 08:58:46 +0200 (CEST) Date: Mon, 6 Oct 2025 08:58:42 +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 , Christopher Healy , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-mm@kvack.org, kernel@collabora.com Subject: Re: [PATCH v3 03/10] drm/gem: Add huge tmpfs mount point helper Message-ID: <20251006085842.047231b0@fedora> In-Reply-To: <20251004093054.21388-4-loic.molinari@collabora.com> References: <20251004093054.21388-1-loic.molinari@collabora.com> <20251004093054.21388-4-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-Stat-Signature: az7qmckpdc7gpc5soyf6tjtu1jphpsqq X-Rspam-User: X-Rspamd-Queue-Id: 25C0AA0008 X-Rspamd-Server: rspam10 X-HE-Tag: 1759733929-678764 X-HE-Meta: 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 NiFVqGbO mqrdiFjmv/p3cImsGcQd8268i/u26QYo+/3plzfRgCRPW8kzg8k3pWX8klXn0WHsQ4R3T/4MGpxjSQZOBx/AGMZGf4PT50xtGaC+2PVWG5JlPAcMnuiRgQPPJf7l4CVCLAqIZRyXN6NZ4QDwiLJXs+OpnGTQnk6dA1rzYpxyk4bo4ihkYMAfaWz7VtPxywF40LPYk0y9J53N6Qmix+qi5iT1yiYzeHWBkp/shpiQTAP+PHmk54ZWDPBOkNuX6VEQ2oeUPmMPggfA7j3XpW8V1VwCIMSAiB/w1pgt+2xGT8rHlojNAQLeeciCWCBVXw0Fs/uApgSRywQe4CktD8NjnBlV4irNQniVpvI5ZhDaehYvBODHDDH4pT1rkRw== 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 Sat, 4 Oct 2025 11:30:46 +0200 Lo=C3=AFc Molinari wrote: > Add the drm_gem_huge_mnt_create() helper to avoid code duplication in > the i915, V3D, Panfrost and Panthor drivers. It creates and mounts a > dedicated huge tmpfs mountpoint, for the lifetime of a drm device, > used at GEM object initialization. >=20 > The next commits will port drivers to this helper. >=20 > v3: > - store huge tmpfs mountpoint in drm_device >=20 > Signed-off-by: Lo=C3=AFc Molinari > --- > drivers/gpu/drm/drm_gem.c | 67 +++++++++++++++++++++++++++++++++++++++ > include/drm/drm_device.h | 11 +++++++ > include/drm/drm_gem.h | 1 + > 3 files changed, 79 insertions(+) >=20 > diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c > index f5a10ff363c9..b4e4947210ef 100644 > --- a/drivers/gpu/drm/drm_gem.c > +++ b/drivers/gpu/drm/drm_gem.c > @@ -29,6 +29,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -82,6 +83,72 @@ > * up at a later date, and as our interface with shmfs for memory alloca= tion. > */ > =20 > +static int drm_gem_add_fc_param(struct fs_context *fc, const char *key, > + const char *value) > +{ > + return vfs_parse_fs_string(fc, key, value, strlen(value)); > +} > + > +static void drm_gem_huge_mnt_free(struct drm_device *dev, void *data) > +{ > + drm_WARN_ON(dev, dev->huge_mnt =3D=3D NULL); > + > + kern_unmount(dev->huge_mnt); > + dev->huge_mnt =3D NULL; > +} > + > +/** > + * 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. Returns -EEXIST if = called > + * more than once for the lifetime of the drm device. > + */ > +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 (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) > + return -EOPNOTSUPP; If we return 0 here, we can get rid of the if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) tests in all the drivers and let them call drm_gem_huge_mnt_create() unconditionally. > + > + type =3D get_fs_type("tmpfs"); > + if (unlikely(!type)) > + return -EOPNOTSUPP; > + > + if (unlikely(dev->huge_mnt)) > + return -EEXIST; > + > + fc =3D fs_context_for_mount(type, SB_KERNMOUNT); > + if (IS_ERR(fc)) > + return PTR_ERR(fc); > + ret =3D drm_gem_add_fc_param(fc, "source", "tmpfs"); > + if (unlikely(ret)) > + return -ENOPARAM; > + ret =3D drm_gem_add_fc_param(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); > + > 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 59fd3f4d5995..895b0ced972e 100644 > --- a/include/drm/drm_device.h > +++ b/include/drm/drm_device.h > @@ -3,6 +3,7 @@ > =20 > #include > #include > +#include > #include > #include > #include > @@ -168,6 +169,16 @@ 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. > + */ > + struct vfsmount *huge_mnt; > + > /** > * @driver_features: per-device driver features > * > diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h > index 7c8bd67d087c..7285a62d9afc 100644 > --- a/include/drm/drm_gem.h > +++ b/include/drm/drm_gem.h > @@ -492,6 +492,7 @@ struct drm_gem_object { > DRM_GEM_FOPS,\ > } > =20 > +int drm_gem_huge_mnt_create(struct drm_device *dev, const char *value); > 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,