linux-kernel - [PATCH 0/8] drm: Optimize page tables overhead with THP

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Message-ID: <20250929200316.18417-1-loic.molinari@collabora.com>
Date: Mon, 29 Sep 2025 22:03:08 +0200
From: Loïc Molinari <loic.molinari@...labora.com>
To: 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>,
	Tvrtko Ursulin <tursulin@...ulin.net>,
	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>,
	Loïc Molinari <loic.molinari@...labora.com>,
	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>
Cc: linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	intel-gfx@...ts.freedesktop.org,
	linux-mm@...ck.org,
	kernel@...labora.com
Subject: [PATCH 0/8] drm: Optimize page tables overhead with THP

This series aims to reduce the page tables overhead of DRM drivers for
builds with CONFIG_TRANSPARENT_HUGEPAGE enabled and either the sysfs
config '/sys/kernel/mm/transparent_hugepage/shmem_enabled'
appropriately set or drivers using a dedicated huge tmpfs mount point.

It starts by adding a huge page fault handler for GEM objects to
insert PMD or PUD mappings whenever the shmem backing store manages to
create huge folios. It then introduces a dedicated get_unmapped_area
file operation on the DRM file descriptor for GEM objects to get the
best virtual address alignment for the underlying shmem buffers.

The remaining commits propose shmem helpers to create and release huge
tmpfs mount points and adapt the i915 and V3D drivers. The helpers are
then used to optionally enable Transparent Hugepage for Panfrost and
Panthor.

Loïc Molinari (8):
  drm/shmem-helper: Add huge page fault handler
  drm/gem: Introduce drm_gem_get_unmapped_area() fop
  drm/shmem-helper: Add huge tmpfs mount point helpers
  drm/i915: Use huge tmpfs mount point helpers
  drm/v3d: Use huge tmpfs mount point helpers
  drm/panthor: Introduce huge tmpfs mount point option
  drm/panthor: Improve IOMMU map/unmap debugging logs
  drm/panfrost: Introduce huge tmpfs mount point option

 drivers/gpu/drm/drm_gem.c                  | 110 ++++++++++++++++----
 drivers/gpu/drm/drm_gem_shmem_helper.c     | 112 ++++++++++++++++++++-
 drivers/gpu/drm/i915/gem/i915_gemfs.c      |  33 +-----
 drivers/gpu/drm/panfrost/panfrost_device.c |   4 +
 drivers/gpu/drm/panfrost/panfrost_device.h |   2 +
 drivers/gpu/drm/panfrost/panfrost_drv.c    |   6 ++
 drivers/gpu/drm/panfrost/panfrost_drv.h    |  11 ++
 drivers/gpu/drm/panfrost/panfrost_gem.c    |  29 +++++-
 drivers/gpu/drm/panfrost/panfrost_gem.h    |   3 +
 drivers/gpu/drm/panthor/panthor_device.c   |   4 +
 drivers/gpu/drm/panthor/panthor_device.h   |   3 +
 drivers/gpu/drm/panthor/panthor_drv.c      |   7 ++
 drivers/gpu/drm/panthor/panthor_drv.h      |  11 ++
 drivers/gpu/drm/panthor/panthor_gem.c      |  30 +++++-
 drivers/gpu/drm/panthor/panthor_gem.h      |   3 +
 drivers/gpu/drm/panthor/panthor_mmu.c      |  19 +++-
 drivers/gpu/drm/v3d/v3d_gemfs.c            |  31 +-----
 include/drm/drm_gem.h                      |   4 +
 include/drm/drm_gem_shmem_helper.h         |  14 +++
 mm/shmem.c                                 |   1 +
 20 files changed, 346 insertions(+), 91 deletions(-)
 create mode 100644 drivers/gpu/drm/panfrost/panfrost_drv.h
 create mode 100644 drivers/gpu/drm/panthor/panthor_drv.h

-- 
2.47.3