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Message-ID: <0130b962-6cd7-4f2c-8fd0-809a21495e03@ursulin.net>
Date: Mon, 20 Oct 2025 10:33:27 +0100
From: Tvrtko Ursulin <tursulin@...ulin.net>
To: Loïc Molinari <loic.molinari@...labora.com>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
Jani Nikula <jani.nikula@...ux.intel.com>,
Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
Rodrigo Vivi <rodrigo.vivi@...el.com>,
Boris Brezillon <boris.brezillon@...labora.com>,
Rob Herring <robh@...nel.org>, Steven Price <steven.price@....com>,
Liviu Dudau <liviu.dudau@....com>, Melissa Wen <mwen@...lia.com>,
Maíra Canal <mcanal@...lia.com>,
Hugh Dickins <hughd@...gle.com>, Baolin Wang
<baolin.wang@...ux.alibaba.com>, Andrew Morton <akpm@...ux-foundation.org>,
Al Viro <viro@...iv.linux.org.uk>, Mikołaj Wasiak
<mikolaj.wasiak@...el.com>, Christian Brauner <brauner@...nel.org>,
Nitin Gote <nitin.r.gote@...el.com>, Andi Shyti
<andi.shyti@...ux.intel.com>, Jonathan Corbet <corbet@....net>,
Christopher Healy <healych@...zon.com>, Matthew Wilcox
<willy@...radead.org>, Bagas Sanjaya <bagasdotme@...il.com>
Cc: linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
intel-gfx@...ts.freedesktop.org, linux-mm@...ck.org,
linux-doc@...r.kernel.org, kernel@...labora.com
Subject: Re: [PATCH v4 07/13] drm/v3d: Use huge tmpfs mount point helper
On 15/10/2025 16:30, Loïc Molinari wrote:
> Make use of the new drm_gem_huge_mnt_create() helper to avoid code
> duplication. Now that it's just a few lines long, the single function
> in v3d_gemfs.c is moved into v3d_gem.c.
>
> v3:
> - use huge tmpfs mountpoint in drm_device
> - move v3d_gemfs.c into v3d_gem.c
>
> v4:
> - clean up mountpoint creation error handling
>
> Signed-off-by: Loïc Molinari <loic.molinari@...labora.com>
> ---
> drivers/gpu/drm/v3d/Makefile | 3 +-
> drivers/gpu/drm/v3d/v3d_bo.c | 5 ++-
> drivers/gpu/drm/v3d/v3d_drv.c | 2 +-
> drivers/gpu/drm/v3d/v3d_drv.h | 11 +-----
> drivers/gpu/drm/v3d/v3d_gem.c | 27 +++++++++++++--
> drivers/gpu/drm/v3d/v3d_gemfs.c | 60 ---------------------------------
> 6 files changed, 30 insertions(+), 78 deletions(-)
> delete mode 100644 drivers/gpu/drm/v3d/v3d_gemfs.c
>
> diff --git a/drivers/gpu/drm/v3d/Makefile b/drivers/gpu/drm/v3d/Makefile
> index fcf710926057..b7d673f1153b 100644
> --- a/drivers/gpu/drm/v3d/Makefile
> +++ b/drivers/gpu/drm/v3d/Makefile
> @@ -13,8 +13,7 @@ v3d-y := \
> v3d_trace_points.o \
> v3d_sched.o \
> v3d_sysfs.o \
> - v3d_submit.o \
> - v3d_gemfs.o
> + v3d_submit.o
>
> v3d-$(CONFIG_DEBUG_FS) += v3d_debugfs.o
>
> diff --git a/drivers/gpu/drm/v3d/v3d_bo.c b/drivers/gpu/drm/v3d/v3d_bo.c
> index c41476ddde68..6b9909bfce82 100644
> --- a/drivers/gpu/drm/v3d/v3d_bo.c
> +++ b/drivers/gpu/drm/v3d/v3d_bo.c
> @@ -112,7 +112,7 @@ v3d_bo_create_finish(struct drm_gem_object *obj)
> if (IS_ERR(sgt))
> return PTR_ERR(sgt);
>
> - if (!v3d->gemfs)
> + if (!obj->dev->huge_mnt)
Maybe it would be a good idea to add a helper for this check. Keeping
aligned with drm_gem_huge_mnt_create() something like
drm_gem_has_huge_mnt()? That would then hide the optional drm_device
struct member if you decide to go for that.
> align = SZ_4K;
> else if (obj->size >= SZ_1M)
> align = SZ_1M;
> @@ -148,12 +148,11 @@ struct v3d_bo *v3d_bo_create(struct drm_device *dev, struct drm_file *file_priv,
> size_t unaligned_size)
> {
> struct drm_gem_shmem_object *shmem_obj;
> - struct v3d_dev *v3d = to_v3d_dev(dev);
> struct v3d_bo *bo;
> int ret;
>
> shmem_obj = drm_gem_shmem_create_with_mnt(dev, unaligned_size,
> - v3d->gemfs);
> + dev->huge_mnt);
Okay this one goes away by the end of the series.
> if (IS_ERR(shmem_obj))
> return ERR_CAST(shmem_obj);
> bo = to_v3d_bo(&shmem_obj->base);
> diff --git a/drivers/gpu/drm/v3d/v3d_drv.c b/drivers/gpu/drm/v3d/v3d_drv.c
> index c5a3bbbc74c5..19ec0ea7f38e 100644
> --- a/drivers/gpu/drm/v3d/v3d_drv.c
> +++ b/drivers/gpu/drm/v3d/v3d_drv.c
> @@ -106,7 +106,7 @@ static int v3d_get_param_ioctl(struct drm_device *dev, void *data,
> args->value = v3d->perfmon_info.max_counters;
> return 0;
> case DRM_V3D_PARAM_SUPPORTS_SUPER_PAGES:
> - args->value = !!v3d->gemfs;
> + args->value = !!dev->huge_mnt;
> return 0;
> case DRM_V3D_PARAM_GLOBAL_RESET_COUNTER:
> mutex_lock(&v3d->reset_lock);
> diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h
> index 1884686985b8..99a39329bb85 100644
> --- a/drivers/gpu/drm/v3d/v3d_drv.h
> +++ b/drivers/gpu/drm/v3d/v3d_drv.h
> @@ -158,11 +158,6 @@ struct v3d_dev {
> struct drm_mm mm;
> spinlock_t mm_lock;
>
> - /*
> - * tmpfs instance used for shmem backed objects
> - */
> - struct vfsmount *gemfs;
> -
> struct work_struct overflow_mem_work;
>
> struct v3d_queue_state queue[V3D_MAX_QUEUES];
> @@ -569,6 +564,7 @@ extern const struct dma_fence_ops v3d_fence_ops;
> struct dma_fence *v3d_fence_create(struct v3d_dev *v3d, enum v3d_queue q);
>
> /* v3d_gem.c */
> +extern bool super_pages;
> int v3d_gem_init(struct drm_device *dev);
> void v3d_gem_destroy(struct drm_device *dev);
> void v3d_reset_sms(struct v3d_dev *v3d);
> @@ -576,11 +572,6 @@ void v3d_reset(struct v3d_dev *v3d);
> void v3d_invalidate_caches(struct v3d_dev *v3d);
> void v3d_clean_caches(struct v3d_dev *v3d);
>
> -/* v3d_gemfs.c */
> -extern bool super_pages;
> -void v3d_gemfs_init(struct v3d_dev *v3d);
> -void v3d_gemfs_fini(struct v3d_dev *v3d);
> -
> /* v3d_submit.c */
> void v3d_job_cleanup(struct v3d_job *job);
> void v3d_job_put(struct v3d_job *job);
> diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
> index bb110d35f749..635ff0fabe7e 100644
> --- a/drivers/gpu/drm/v3d/v3d_gem.c
> +++ b/drivers/gpu/drm/v3d/v3d_gem.c
> @@ -258,6 +258,30 @@ v3d_invalidate_caches(struct v3d_dev *v3d)
> v3d_invalidate_slices(v3d, 0);
> }
>
> +static void
> +v3d_huge_mnt_init(struct v3d_dev *v3d)
> +{
> + int err = 0;
> +
> + /*
> + * By using a huge shmemfs mountpoint when the user wants to
> + * enable Super Pages, we can pass in mount flags that better
> + * match our usecase.
> + */
> +
> + if (super_pages)
> + err = drm_gem_huge_mnt_create(&v3d->drm, "within_size");
If it is this patch that is creating the build failure then the two
should be squashed.
Then in "drm/v3d: Fix builds with CONFIG_TRANSPARENT_HUGEPAGE=n" this
ends up a bit ugly:
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
if (super_pages)
#endif
err = drm_gem_huge_mnt_create(&v3d->drm, "within_size");
Does this not work:
if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && super_pages)
err = drm_gem_huge_mnt_create(&v3d->drm, "within_size");
?
Regards,
Tvrtko
> +
> + if (v3d->drm.huge_mnt)
> + drm_info(&v3d->drm, "Using Transparent Hugepages\n");
> + else if (err)
> + drm_warn(&v3d->drm, "Can't use Transparent Hugepages (%d)\n",
> + err);
> + else
> + drm_notice(&v3d->drm,
> + "Transparent Hugepage support is recommended for optimal performance on this platform!\n");
> +}
> +
> int
> v3d_gem_init(struct drm_device *dev)
> {
> @@ -309,7 +333,7 @@ v3d_gem_init(struct drm_device *dev)
> v3d_init_hw_state(v3d);
> v3d_mmu_set_page_table(v3d);
>
> - v3d_gemfs_init(v3d);
> + v3d_huge_mnt_init(v3d);
>
> ret = v3d_sched_init(v3d);
> if (ret) {
> @@ -329,7 +353,6 @@ v3d_gem_destroy(struct drm_device *dev)
> enum v3d_queue q;
>
> v3d_sched_fini(v3d);
> - v3d_gemfs_fini(v3d);
>
> /* Waiting for jobs to finish would need to be done before
> * unregistering V3D.
> diff --git a/drivers/gpu/drm/v3d/v3d_gemfs.c b/drivers/gpu/drm/v3d/v3d_gemfs.c
> deleted file mode 100644
> index c1a30166c099..000000000000
> --- a/drivers/gpu/drm/v3d/v3d_gemfs.c
> +++ /dev/null
> @@ -1,60 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0+
> -/* Copyright (C) 2024 Raspberry Pi */
> -
> -#include <linux/fs.h>
> -#include <linux/mount.h>
> -#include <linux/fs_context.h>
> -
> -#include "v3d_drv.h"
> -
> -void v3d_gemfs_init(struct v3d_dev *v3d)
> -{
> - 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. However, we
> - * only do so on platforms which benefit from it.
> - */
> - if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
> - goto err;
> -
> - /* The user doesn't want to enable Super Pages */
> - if (!super_pages)
> - 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;
> -
> - v3d->gemfs = gemfs;
> - drm_info(&v3d->drm, "Using Transparent Hugepages\n");
> -
> - return;
> -
> -err:
> - v3d->gemfs = NULL;
> - drm_notice(&v3d->drm,
> - "Transparent Hugepage support is recommended for optimal performance on this platform!\n");
> -}
> -
> -void v3d_gemfs_fini(struct v3d_dev *v3d)
> -{
> - if (v3d->gemfs)
> - kern_unmount(v3d->gemfs);
> -}
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