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Thu, 20 Nov 2025 01:31:53 -0800 (PST) Message-ID: Date: Thu, 20 Nov 2025 09:31:53 +0000 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 05/11] drm/i915: Use huge tmpfs mountpoint helpers To: =?UTF-8?Q?Lo=C3=AFc_Molinari?= , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Boris Brezillon , Rob Herring , Steven Price , Liviu Dudau , Melissa Wen , =?UTF-8?Q?Ma=C3=ADra_Canal?= , Hugh Dickins , Baolin Wang , Andrew Morton , Al Viro , =?UTF-8?Q?Miko=C5=82aj_Wasiak?= , Christian Brauner , Nitin Gote , Andi Shyti , Jonathan Corbet , Christopher Healy , Matthew Wilcox , Bagas Sanjaya Cc: 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 References: <20251114170303.2800-1-loic.molinari@collabora.com> <20251114170303.2800-6-loic.molinari@collabora.com> Content-Language: en-GB From: Tvrtko Ursulin In-Reply-To: <20251114170303.2800-6-loic.molinari@collabora.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 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 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 > --- > 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 > > #include > +#include > +#include > > #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 > -#include > -#include > - > -#include > - > -#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? 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;