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Message-ID: <85b2c930-54e3-4172-b46b-54bd408271ff@collabora.com>
Date: Mon, 20 Oct 2025 16:27:34 +0200
From: Loïc Molinari <loic.molinari@...labora.com>
To: Tvrtko Ursulin <tursulin@...ulin.net>,
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 20/10/2025 11:33, Tvrtko Ursulin wrote:
>
> 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.
Sounds good. This would prevent cluttering code with ifdefs in drivers
while still removing the huge_mnt field in drm_device in builds with
CONFIG_TRANSPARENT_HUGEPAGE=n. I'll propose a new version doing so.
>
>> 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");
>
> ?
I've got a new version ready that does exactly that (after discussing
with Boris).
>
> 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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