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Message-ID: <34675e64-d74f-4484-8d18-37dfec46acc7@collabora.com>
Date: Fri, 5 Dec 2025 09:37:42 +0100
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 v9 05/11] drm/i915: Use huge tmpfs mountpoint helpers
Hi Tvrtko,
On 02/12/2025 12:01, Tvrtko Ursulin wrote:
>
> On 28/11/2025 18:41, Loïc Molinari wrote:
>> On 20/11/2025 10:31, Tvrtko Ursulin wrote:
>>>
>>> On 14/11/2025 17:02, Loïc Molinari wrote:
>>>> Make use of the new drm_gem_huge_mnt_create() and
>>>> drm_gem_get_huge_mnt() helpers to avoid code duplication. Now that
>>>> it's just a few lines long, the single function in i915_gemfs.c is
>>>> moved into v3d_gem_shmem.c.
>>>>
>>>> v3:
>>>> - use huge tmpfs mountpoint in drm_device
>>>> - move i915_gemfs.c into i915_gem_shmem.c
>>>>
>>>> v4:
>>>> - clean up mountpoint creation error handling
>>>>
>>>> v5:
>>>> - use drm_gem_has_huge_mnt() helper
>>>>
>>>> v7:
>>>> - include <drm/drm_print.h> in i915_gem_shmem.c
>>>>
>>>> v8:
>>>> - keep logging notice message with CONFIG_TRANSPARENT_HUGEPAGE=n
>>>> - don't access huge_mnt field with CONFIG_TRANSPARENT_HUGEPAGE=n
>>>>
>>>> v9:
>>>> - replace drm_gem_has_huge_mnt() by drm_gem_get_huge_mnt()
>>>> - remove useless ternary op test in selftests/huge_pages.c
>>>>
>>>> Signed-off-by: Loïc Molinari <loic.molinari@...labora.com>
>>>> ---
>>>> drivers/gpu/drm/i915/Makefile | 3 +-
>>>> drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 48 +++++++++----
>>>> drivers/gpu/drm/i915/gem/i915_gemfs.c | 71
>>>> -------------------
>>>> drivers/gpu/drm/i915/gem/i915_gemfs.h | 14 ----
>>>> .../gpu/drm/i915/gem/selftests/huge_pages.c | 16 +++--
>>>> drivers/gpu/drm/i915/i915_drv.h | 5 --
>>>> 6 files changed, 47 insertions(+), 110 deletions(-)
>>>> delete mode 100644 drivers/gpu/drm/i915/gem/i915_gemfs.c
>>>> delete mode 100644 drivers/gpu/drm/i915/gem/i915_gemfs.h
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/
>>>> Makefile
>>>> index 84ec79b64960..b5a8c0a6b747 100644
>>>> --- a/drivers/gpu/drm/i915/Makefile
>>>> +++ b/drivers/gpu/drm/i915/Makefile
>>>> @@ -169,8 +169,7 @@ gem-y += \
>>>> gem/i915_gem_ttm_move.o \
>>>> gem/i915_gem_ttm_pm.o \
>>>> gem/i915_gem_userptr.o \
>>>> - gem/i915_gem_wait.o \
>>>> - gem/i915_gemfs.o
>>>> + gem/i915_gem_wait.o
>>>> i915-y += \
>>>> $(gem-y) \
>>>> i915_active.o \
>>>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/
>>>> gpu/ drm/i915/gem/i915_gem_shmem.c
>>>> index 26dda55a07ff..15c2c6fde2ac 100644
>>>> --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
>>>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
>>>> @@ -9,14 +9,16 @@
>>>> #include <linux/uio.h>
>>>> #include <drm/drm_cache.h>
>>>> +#include <drm/drm_gem.h>
>>>> +#include <drm/drm_print.h>
>>>> #include "gem/i915_gem_region.h"
>>>> #include "i915_drv.h"
>>>> #include "i915_gem_object.h"
>>>> #include "i915_gem_tiling.h"
>>>> -#include "i915_gemfs.h"
>>>> #include "i915_scatterlist.h"
>>>> #include "i915_trace.h"
>>>> +#include "i915_utils.h"
>>>> /*
>>>> * Move folios to appropriate lru and release the batch,
>>>> decrementing the
>>>> @@ -497,6 +499,7 @@ static int __create_shmem(struct
>>>> drm_i915_private *i915,
>>>> resource_size_t size)
>>>> {
>>>> unsigned long flags = VM_NORESERVE;
>>>> + struct vfsmount *huge_mnt;
>>>> struct file *filp;
>>>> drm_gem_private_object_init(&i915->drm, obj, size);
>>>> @@ -515,9 +518,9 @@ static int __create_shmem(struct
>>>> drm_i915_private *i915,
>>>> if (BITS_PER_LONG == 64 && size > MAX_LFS_FILESIZE)
>>>> return -E2BIG;
>>>> - if (i915->mm.gemfs)
>>>> - filp = shmem_file_setup_with_mnt(i915->mm.gemfs, "i915", size,
>>>> - flags);
>>>> + huge_mnt = drm_gem_get_huge_mnt(&i915->drm);
>>>> + if (huge_mnt)
>>>> + filp = shmem_file_setup_with_mnt(huge_mnt, "i915", size,
>>>> flags);
>>>> else
>>>> filp = shmem_file_setup("i915", size, flags);
>>>> if (IS_ERR(filp))
>>>> @@ -644,21 +647,40 @@ i915_gem_object_create_shmem_from_data(struct
>>>> drm_i915_private *i915,
>>>> static int init_shmem(struct intel_memory_region *mem)
>>>> {
>>>> - i915_gemfs_init(mem->i915);
>>>> - intel_memory_region_set_name(mem, "system");
>>>> + struct drm_i915_private *i915 = mem->i915;
>>>> - return 0; /* We have fallback to the kernel mnt if gemfs init
>>>> failed. */
>>>> -}
>>>> + /*
>>>> + * By creating our own shmemfs mountpoint, we can pass in
>>>> + * mount flags that better match our usecase.
>>>> + *
>>>> + * One example, although it is probably better with a per-file
>>>> + * control, is selecting huge page allocations
>>>> ("huge=within_size").
>>>> + * However, we only do so on platforms which benefit from it,
>>>> or to
>>>> + * offset the overhead of iommu lookups, where with latter it
>>>> is a net
>>>> + * win even on platforms which would otherwise see some
>>>> performance
>>>> + * regressions such a slow reads issue on Broadwell and Skylake.
>>>> + */
>>>> -static int release_shmem(struct intel_memory_region *mem)
>>>> -{
>>>> - i915_gemfs_fini(mem->i915);
>>>> - return 0;
>>>> + if (GRAPHICS_VER(i915) < 11 && !i915_vtd_active(i915))
>>>> + goto no_thp;
>>>> +
>>>> + drm_gem_huge_mnt_create(&i915->drm, "within_size");
>>>> + if (drm_gem_get_huge_mnt(&i915->drm))
>>>> + drm_info(&i915->drm, "Using Transparent Hugepages\n");
>>>> + else
>>>> + drm_notice(&i915->drm,
>>>> + "Transparent Hugepage support is recommended for
>>>> optimal performance%s\n",
>>>> + GRAPHICS_VER(i915) >= 11 ? " on this platform!" :
>>>> + " when IOMMU is enabled!");
>>>> +
>>>> + no_thp:
>>>> + intel_memory_region_set_name(mem, "system");
>>>> +
>>>> + return 0; /* We have fallback to the kernel mnt if huge mnt
>>>> failed. */
>>>> }
>>>> static const struct intel_memory_region_ops shmem_region_ops = {
>>>> .init = init_shmem,
>>>> - .release = release_shmem,
>>>> .init_object = shmem_object_init,
>>>> };
>>>> diff --git a/drivers/gpu/drm/i915/gem/i915_gemfs.c b/drivers/gpu/
>>>> drm/ i915/gem/i915_gemfs.c
>>>> deleted file mode 100644
>>>> index 1f1290214031..000000000000
>>>> --- a/drivers/gpu/drm/i915/gem/i915_gemfs.c
>>>> +++ /dev/null
>>>> @@ -1,71 +0,0 @@
>>>> -// SPDX-License-Identifier: MIT
>>>> -/*
>>>> - * Copyright © 2017 Intel Corporation
>>>> - */
>>>> -
>>>> -#include <linux/fs.h>
>>>> -#include <linux/mount.h>
>>>> -#include <linux/fs_context.h>
>>>> -
>>>> -#include <drm/drm_print.h>
>>>> -
>>>> -#include "i915_drv.h"
>>>> -#include "i915_gemfs.h"
>>>> -#include "i915_utils.h"
>>>> -
>>>> -void i915_gemfs_init(struct drm_i915_private *i915)
>>>> -{
>>>> - 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.
>>>> - *
>>>> - * One example, although it is probably better with a per-file
>>>> - * control, is selecting huge page allocations
>>>> ("huge=within_size").
>>>> - * However, we only do so on platforms which benefit from it,
>>>> or to
>>>> - * offset the overhead of iommu lookups, where with latter it
>>>> is a net
>>>> - * win even on platforms which would otherwise see some
>>>> performance
>>>> - * regressions such a slow reads issue on Broadwell and Skylake.
>>>> - */
>>>> -
>>>> - if (GRAPHICS_VER(i915) < 11 && !i915_vtd_active(i915))
>>>> - return;
>>>> -
>>>> - if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
>>>> - 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;
>>>> -
>>>> - i915->mm.gemfs = gemfs;
>>>> - drm_info(&i915->drm, "Using Transparent Hugepages\n");
>>>> - return;
>>>> -
>>>> -err:
>>>> - drm_notice(&i915->drm,
>>>> - "Transparent Hugepage support is recommended for optimal
>>>> performance%s\n",
>>>> - GRAPHICS_VER(i915) >= 11 ? " on this platform!" :
>>>> - " when IOMMU is enabled!");
>>>> -}
>>>> -
>>>> -void i915_gemfs_fini(struct drm_i915_private *i915)
>>>> -{
>>>> - kern_unmount(i915->mm.gemfs);
>>>> -}
>>>> diff --git a/drivers/gpu/drm/i915/gem/i915_gemfs.h b/drivers/gpu/
>>>> drm/ i915/gem/i915_gemfs.h
>>>> deleted file mode 100644
>>>> index 16d4333c9a4e..000000000000
>>>> --- a/drivers/gpu/drm/i915/gem/i915_gemfs.h
>>>> +++ /dev/null
>>>> @@ -1,14 +0,0 @@
>>>> -/* SPDX-License-Identifier: MIT */
>>>> -/*
>>>> - * Copyright © 2017 Intel Corporation
>>>> - */
>>>> -
>>>> -#ifndef __I915_GEMFS_H__
>>>> -#define __I915_GEMFS_H__
>>>> -
>>>> -struct drm_i915_private;
>>>> -
>>>> -void i915_gemfs_init(struct drm_i915_private *i915);
>>>> -void i915_gemfs_fini(struct drm_i915_private *i915);
>>>> -
>>>> -#endif
>>>> diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c b/
>>>> drivers/gpu/drm/i915/gem/selftests/huge_pages.c
>>>> index bd08605a1611..28aef75630a2 100644
>>>> --- a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
>>>> +++ b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
>>>> @@ -1316,7 +1316,7 @@ typedef struct drm_i915_gem_object *
>>>> static inline bool igt_can_allocate_thp(struct drm_i915_private
>>>> *i915)
>>>> {
>>>> - return i915->mm.gemfs && has_transparent_hugepage();
>>>> + return !!drm_gem_get_huge_mnt(&i915->drm);
>>>> }
>>>> static struct drm_i915_gem_object *
>>>> @@ -1761,7 +1761,9 @@ static int igt_tmpfs_fallback(void *arg)
>>>> struct drm_i915_private *i915 = arg;
>>>> struct i915_address_space *vm;
>>>> struct i915_gem_context *ctx;
>>>> - struct vfsmount *gemfs = i915->mm.gemfs;
>>>> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>>>> + struct vfsmount *huge_mnt = i915->drm.huge_mnt;
>>>> +#endif
>>>> struct drm_i915_gem_object *obj;
>>>> struct i915_vma *vma;
>>>> struct file *file;
>>>> @@ -1782,10 +1784,12 @@ static int igt_tmpfs_fallback(void *arg)
>>>> /*
>>>> * Make sure that we don't burst into a ball of flames upon
>>>> falling back
>>>> * to tmpfs, which we rely on if on the off-chance we
>>>> encounter a failure
>>>> - * when setting up gemfs.
>>>> + * when setting up a huge mountpoint.
>>>> */
>>>> - i915->mm.gemfs = NULL;
>>>> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>>>> + i915->drm.huge_mnt = NULL;
>>>> +#endif
>>>> obj = i915_gem_object_create_shmem(i915, PAGE_SIZE);
>>>> if (IS_ERR(obj)) {
>>>> @@ -1819,7 +1823,9 @@ static int igt_tmpfs_fallback(void *arg)
>>>> out_put:
>>>> i915_gem_object_put(obj);
>>>> out_restore:
>>>> - i915->mm.gemfs = gemfs;
>>>> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>>>> + i915->drm.huge_mnt = huge_mnt;
>>>> +#endif
>>>
>>> Apart from this layering violation in the selftest, this version
>>> looks good to me. I am just wondering if we could somehow improve
>>> this aspect. I was thinking a self-test builds only special version
>>> of i915_gem_object_create_shmem. Call chain is deep but there are
>>> flags passed on:
>>>
>>> i915_gem_object_create_shmem
>>> i915_gem_object_create_region
>>> __i915_gem_object_create_region
>>> err = mem->ops->init_object(
>>>
>>> So we could add a new helper like:
>>>
>>> selftests_create_shmem
>>> i915_gem_object_create_region(...flags =
>>> I915_BO_ALLOC_SELFTESTS_NOTHP...)
>>>
>>> And in __create_shmem we just make it:
>>>
>>> ...
>>> huge_mnt = drm_gem_get_huge_mnt(&i915->drm) &&
>>> if (IS_ENABLED(..SELFTESTS..) &&
>>> (flags & I915_BO_ALLOC_SELFTESTS_NOTHP))
>>> huge_mnt = NULL;
>>> ...
>>>
>>> It would avoid the ifdef and needing to play games with the DRM
>>> internals.
>>>
>>> How does that sound to you?
>>
>> That sounds better to me but I'm not very familiar with the i915
>> testing process. Would you be ready to accept the currect ifdef'd
>> version for now and let me take a better look at that proposal later
>> for a follow-up patch series?
>
> I would rather we do it in one go. I assume you are compile testing the
> i915 part? I so, would you be happy to integrate something like this in
> your patch (adjusted for your changes):
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h b/drivers/
> gpu/drm/i915/gem/i915_gem_object_types.h
> index 465ce94aee76..4dbd61280c93 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> @@ -348,12 +348,14 @@ struct drm_i915_gem_object {
> */
> #define I915_BO_ALLOC_GPU_ONLY BIT(6)
> #define I915_BO_ALLOC_CCS_AUX BIT(7)
> +#define I915_BO_ALLOC_NOTHP BIT(8)
> /*
> * Object is allowed to retain its initial data and will not be
> cleared on first
> * access if used along with I915_BO_ALLOC_USER. This is mainly to keep
> * preallocated framebuffer data intact while transitioning it to
> i915drmfb.
> */
> -#define I915_BO_PREALLOC BIT(8)
> +#define I915_BO_PREALLOC BIT(9)
> +
> #define I915_BO_ALLOC_FLAGS (I915_BO_ALLOC_CONTIGUOUS | \
> I915_BO_ALLOC_VOLATILE | \
> I915_BO_ALLOC_CPU_CLEAR | \
> @@ -362,10 +364,12 @@ struct drm_i915_gem_object {
> I915_BO_ALLOC_PM_EARLY | \
> I915_BO_ALLOC_GPU_ONLY | \
> I915_BO_ALLOC_CCS_AUX | \
> + I915_BO_ALLOC_NOTHP | \
> I915_BO_PREALLOC)
> -#define I915_BO_READONLY BIT(9)
> -#define I915_TILING_QUIRK_BIT 10 /* unknown swizzling; do not
> release! */
> -#define I915_BO_PROTECTED BIT(11)
> +#define I915_BO_READONLY BIT(10)
> +#define I915_TILING_QUIRK_BIT 11 /* unknown swizzling; do not
> release! */
> +#define I915_BO_PROTECTED BIT(12)
> +
> /**
> * @mem_flags - Mutable placement-related flags
> *
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/
> drm/i915/gem/i915_gem_shmem.c
> index 26dda55a07ff..a1e876ce7bb9 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> @@ -494,7 +494,8 @@ const struct drm_i915_gem_object_ops
> i915_gem_shmem_ops = {
>
> static int __create_shmem(struct drm_i915_private *i915,
> struct drm_gem_object *obj,
> - resource_size_t size)
> + resource_size_t size,
> + unsigned int flags)
> {
> unsigned long flags = VM_NORESERVE;
> struct file *filp;
> @@ -515,7 +516,7 @@ static int __create_shmem(struct drm_i915_private
> *i915,
> if (BITS_PER_LONG == 64 && size > MAX_LFS_FILESIZE)
> return -E2BIG;
>
> - if (i915->mm.gemfs)
> + if (!(flags & I915_BO_ALLOC_NOTHP) && i915->mm.gemfs)
> filp = shmem_file_setup_with_mnt(i915->mm.gemfs, "i915", size,
> flags);
> else
> @@ -548,7 +549,7 @@ static int shmem_object_init(struct
> intel_memory_region *mem,
> gfp_t mask;
> int ret;
>
> - ret = __create_shmem(i915, &obj->base, size);
> + ret = __create_shmem(i915, &obj->base, size, flags);
> if (ret)
> return ret;
>
> diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c b/drivers/
> gpu/drm/i915/gem/selftests/huge_pages.c
> index bd08605a1611..c296af381007 100644
> --- a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
> +++ b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
> @@ -1787,7 +1787,8 @@ static int igt_tmpfs_fallback(void *arg)
>
> i915->mm.gemfs = NULL;
>
> - obj = i915_gem_object_create_shmem(i915, PAGE_SIZE);
> + obj = i915_gem_object_create_region(i915-
> >mm.regions[INTEL_REGION_SMEM],
> + PAGE_SIZE, 0, I915_BO_ALLOC_NOTHP);
> if (IS_ERR(obj)) {
> err = PTR_ERR(obj);
> goto out_restore;
>
>
> If it compiles I would take that and will handle any CI fall out.
Thanks for that! I've integrated it into my i915 patch and compile
tested it. I'll send a new version.
Regards,
Loïc
> Regards,
>
> Tvrtko
>
>
>> Regards,
>>
>> Loïc
>>
>>> Regards,
>>>
>>> Tvrtko
>>>
>>>> i915_vm_put(vm);
>>>> out:
>>>> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/
>>>> i915_drv.h
>>>> index 95f9ddf22ce4..93a5af3de334 100644
>>>> --- a/drivers/gpu/drm/i915/i915_drv.h
>>>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>>>> @@ -141,11 +141,6 @@ struct i915_gem_mm {
>>>> */
>>>> atomic_t free_count;
>>>> - /**
>>>> - * tmpfs instance used for shmem backed objects
>>>> - */
>>>> - struct vfsmount *gemfs;
>>>> -
>>>> struct intel_memory_region *regions[INTEL_REGION_UNKNOWN];
>>>> struct notifier_block oom_notifier;
>>
>
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