kernel/linux.git/drivers/gpu/drm/drm_gem.c, branch v6.1.168

drm/gem: Fix race in drm_gem_handle_create_tail()

2025-07-17T16:32:08+00:00

commit bd46cece51a36ef088f22ef0416ac13b0a46d5b0 upstream. Object creation is a careful dance where we must guarantee that the object is fully constructed before it is visible to other threads, and GEM buffer objects are no difference. Final publishing happens by calling drm_gem_handle_create(). After that the only allowed thing to do is call drm_gem_object_put() because a concurrent call to the GEM_CLOSE ioctl with a correctly guessed id (which is trivial since we have a linear allocator) can already tear down the object again. Luckily most drivers get this right, the very few exceptions I've pinged the relevant maintainers for. Unfortunately we also need drm_gem_handle_create() when creating additional handles for an already existing object (e.g. GETFB ioctl or the various bo import ioctl), and hence we cannot have a drm_gem_handle_create_and_put() as the only exported function to stop these issues from happening. Now unfortunately the implementation of drm_gem_handle_create() isn't living up to standards: It does correctly finishe object initialization at the global level, and hence is safe against a concurrent tear down. But it also sets up the file-private aspects of the handle, and that part goes wrong: We fully register the object in the drm_file.object_idr before calling drm_vma_node_allow() or obj->funcs->open, which opens up races against concurrent removal of that handle in drm_gem_handle_delete(). Fix this with the usual two-stage approach of first reserving the handle id, and then only registering the object after we've completed the file-private setup. Jacek reported this with a testcase of concurrently calling GEM_CLOSE on a freshly-created object (which also destroys the object), but it should be possible to hit this with just additional handles created through import or GETFB without completed destroying the underlying object with the concurrent GEM_CLOSE ioctl calls. Note that the close-side of this race was fixed in f6cd7daecff5 ("drm: Release driver references to handle before making it available again"), which means a cool 9 years have passed until someone noticed that we need to make this symmetry or there's still gaps left :-/ Without the 2-stage close approach we'd still have a race, therefore that's an integral part of this bugfix. More importantly, this means we can have NULL pointers behind allocated id in our drm_file.object_idr. We need to check for that now: - drm_gem_handle_delete() checks for ERR_OR_NULL already - drm_gem.c:object_lookup() also chekcs for NULL - drm_gem_release() should never be called if there's another thread still existing that could call into an IOCTL that creates a new handle, so cannot race. For paranoia I added a NULL check to drm_gem_object_release_handle() though. - most drivers (etnaviv, i915, msm) are find because they use idr_find(), which maps both ENOENT and NULL to NULL. - drivers using idr_for_each_entry() should also be fine, because idr_get_next does filter out NULL entries and continues the iteration. - The same holds for drm_show_memory_stats(). v2: Use drm_WARN_ON (Thomas) Reported-by: Jacek Lawrynowicz Tested-by: Jacek Lawrynowicz Reviewed-by: Thomas Zimmermann Cc: stable@vger.kernel.org Cc: Jacek Lawrynowicz Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Thomas Zimmermann Cc: David Airlie Cc: Simona Vetter Signed-off-by: Simona Vetter Signed-off-by: Simona Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20250707151814.603897-1-simona.vetter@ffwll.ch Signed-off-by: Greg Kroah-Hartman

drm/msm/gem: Prevent blocking within shrinker loop

2023-03-22T12:33:39+00:00

[ Upstream commit 9630b585b607bd26f505d34620b14d75b9a5af7d ] Consider this scenario: 1. APP1 continuously creates lots of small GEMs 2. APP2 triggers `drop_caches` 3. Shrinker starts to evict APP1 GEMs, while APP1 produces new purgeable GEMs 4. msm_gem_shrinker_scan() returns non-zero number of freed pages and causes shrinker to try shrink more 5. msm_gem_shrinker_scan() returns non-zero number of freed pages again, goto 4 6. The APP2 is blocked in `drop_caches` until APP1 stops producing purgeable GEMs To prevent this blocking scenario, check number of remaining pages that GPU shrinker couldn't release due to a GEM locking contention or shrinking rejection. If there are no remaining pages left to shrink, then there is no need to free up more pages and shrinker may break out from the loop. This problem was found during shrinker/madvise IOCTL testing of virtio-gpu driver. The MSM driver is affected in the same way. Reviewed-by: Rob Clark Reviewed-by: Thomas Zimmermann Fixes: b352ba54a820 ("drm/msm/gem: Convert to using drm_gem_lru") Signed-off-by: Dmitry Osipenko Link: https://lore.kernel.org/all/20230108210445.3948344-2-dmitry.osipenko@collabora.com/ Signed-off-by: Sasha Levin

Merge tag 'drm-next-2022-10-05' of git://anongit.freedesktop.org/drm/drm

2022-10-05T18:24:12+00:00

Pull drm updates from Dave Airlie: "Lots of stuff all over, some new AMD IP support and gang submit support. i915 has further DG2 and Meteorlake pieces, and a bunch of i915 display refactoring. msm has a shrinker rework. There are also a bunch of conversions to use kunit. This has two external pieces, some MEI changes needed for future Intel discrete GPUs. These should be acked by Greg. There is also a cross maintainer shared tree with some backlight rework from Hans in here. Core: - convert selftests to kunit - managed init for more objects - move to idr_init_base - rename fb and gem cma helpers to dma - hide unregistered connectors from getconnector ioctl - DSC passthrough aux support - backlight handling improvements - add dma_resv_assert_held to vmap/vunmap edid: - move luminance calculation to core fbdev: - fix aperture helper usage fourcc: - add more format helpers - add DRM_FORMAT_Cxx, DRM_FORMAT_Rxx, DRM_FORMAT_Dxx - add packed AYUV8888, XYUV8888 - add some kunit tests ttm: - allow bos without backing store - rewrite placement to use intersect/compatible functions dma-buf: - docs update - improve signalling when debugging udmabuf: - fix failure path GPF dp: - drop dp/mst legacy code - atomic mst state support - audio infoframe packing panel: - Samsung LTL101AL01 - B120XAN01.0 - R140NWF5 RH - DMT028VGHMCMI-1A T - AUO B133UAN02.1 - IVO M133NW4J-R3 - Innolux N120ACA-EA1 amdgpu: - Gang submit support - Mode2 reset for RDNA2 - New IP support: DCN 3.1.4, 3.2 SMU 13.x NBIO 7.7 GC 11.x PSP 13.x SDMA 6.x GMC 11.x - DSC passthrough support - PSP fixes for TA support - vangogh GFXOFF stats - clang fixes - gang submit CS cleanup prep work - fix VRAM eviction issues amdkfd: - GC 10.3 IP ISA fixes - fix CRIU regression - CPU fault on COW mapping fixes i915: - align fw versioning with kernel practices - add display substruct to i915 private - add initial runtime info to driver info - split out HDCP and backlight registers - MEI XeHP SDV GSC support - add per-gt sysfs defaults - TLB invalidation improvements - Disable PCI BAR resize on 32-bit - GuC firmware updates and compat changes - GuC log timestamp translation - DG2 preemption workaround changes - DG2 improved HDMI pixel clocks support - PCI BAR sanity checks - Enable DC5 on DG2 - DG2 DMC fw bumped - ADL-S PCI ID added - Meteorlake enablement - Rename ggtt_view to gtt_view - host RPS fixes - release mmaps on rpm suspend on discrete - clocking and dpll refactoring - VBT definitions and parsing updates - SKL watermark code extracted to separate file - allow seamless M/N changes on eDP panels - BUG_ON removal and cleanups msm: - DPU: simplified VBIF configuration cleanup CTL interfaces - DSI: removed unused msm_display_dsc_config struct switch regulator calls to new API switched to PANEL_BRIDGE for direct attached panels - DSI_PHY: convert drivers to parent_hws - DP: cleanup pixel_rate handling - HDMI: turned hdmi-phy-8996 into OF clk provider - misc dt-bindings fixes - choose eDP as primary display if it's available - support getting interconnects from either the mdss or the mdp5/dpu device nodes - gem: Shrinker + LRU re-work: - adds a shared GEM LRU+shrinker helper and moves msm over to that - reduce lock contention between retire and submit by avoiding the need to acquire obj lock in retire path (and instead using resv seeing obj's busyness in the shrinker - fix reclaim vs submit issues - GEM fault injection for triggering userspace error paths - Map/unmap optimization - Improved robustness for a6xx GPU recovery virtio: - improve error and edge conditions handling - convert to use managed helpers - stop exposing LINEAR modifier mgag200: - split modeset handling per model udl: - suspend/disconnect handling improvements vc4: - rework HDMI power up - depend on PM - better unplugging support ast: - resolution handling improvements ingenic: - add JZ4760(B) support - avoid a modeset when sharpness property is unchanged - use the new PM ops it6505: - power seq and clock updates ssd130x: - regmap bulk write - use atomic helpers instead of simple helpers via: - rename via_drv to via_dri1, consolidate all code. radeon: - drop DP MST experimental support - delayed work flush fix - use time_after ti-sn65dsi86: - DP support mediatek: - MT8195 DP support - drop of_gpio header - remove unneeded result - small DP code improvements vkms: - RGB565, XRGB64 and ARGB64 support sun4i: - tv: convert to atomic rcar-du: - Synopsys DW HDMI bridge DT bindings update exynos: - use drm_display_info.is_hdmi - correct return of mixer_mode_valid and hdmi_mode_valid omap: - refcounting fix rockchip: - RK3568 support - RK3399 gamma support" * tag 'drm-next-2022-10-05' of git://anongit.freedesktop.org/drm/drm: (1374 commits) drm/amdkfd: Fix UBSAN shift-out-of-bounds warning drm/amdkfd: Track unified memory when switching xnack mode drm/amdgpu: Enable sram on vcn_4_0_2 drm/amdgpu: Enable VCN DPG for GC11_0_1 drm/msm: Fix build break with recent mm tree drm/panel: simple: Use dev_err_probe() to simplify code drm/panel: panel-edp: Use dev_err_probe() to simplify code drm/panel: simple: Add Multi-Inno Technology MI0800FT-9 dt-bindings: display: simple: Add Multi-Inno Technology MI0800FT-9 panel drm/amdgpu: correct the memcpy size for ip discovery firmware drm/amdgpu: Skip put_reset_domain if it doesn't exist drm/amdgpu: remove switch from amdgpu_gmc_noretry_set drm/amdgpu: Fix mc_umc_status used uninitialized warning drm/amd/display: Prevent OTG shutdown during PSR SU drm/amdgpu: add page retirement handling for CPU RAS drm/amdgpu: use RAS error address convert api in mca notifier drm/amdgpu: support to convert dedicated umc mca address drm/amdgpu: export umc error address convert interface drm/amdgpu: fix sdma v4 init microcode error drm/amd/display: fix array-bounds error in dc_stream_remove_writeback() ...

drm/gem: Add LRU/shrinker helper

2022-08-27T16:32:45+00:00

Add a simple LRU helper to assist with driver's shrinker implementation. It handles tracking the number of backing pages associated with a given LRU, and provides a helper to implement shrinker_scan. A driver can use multiple LRU instances to track objects in various states, for example a dontneed LRU for purgeable objects, a willneed LRU for evictable objects, and an unpinned LRU for objects without backing pages. All LRUs that the object can be moved between must share a single lock. v2: lockdep_assert_held() instead of WARN_ON(!mutex_is_locked()) v3: make drm_gem_lru_move_tail_locked() static until there is a user Cc: Daniel Vetter Cc: Thomas Zimmermann Cc: Dmitry Osipenko Signed-off-by: Rob Clark Reviewed-by: Dmitry Osipenko Patchwork: https://patchwork.freedesktop.org/patch/496128/ Link: https://lore.kernel.org/r/20220802155152.1727594-10-robdclark@gmail.com

drm/gem: Fix GEM handle release errors

2022-08-19T11:38:12+00:00

Currently we are assuming a one to one mapping between dmabuf and GEM handle when releasing GEM handles. But that is not always true, since we would create extra handles for the GEM obj in cases like gem_open() and getfb{,2}(). A similar issue was reported at: https://lore.kernel.org/all/20211105083308.392156-1-jay.xu@rock-chips.com/ Another problem is that the imported dmabuf might not always have gem_obj->dma_buf set, which would cause leaks in drm_gem_remove_prime_handles(). Let's fix these for now by using handle to find the exact map to remove. Signed-off-by: Jeffy Chen Reviewed-by: Christian König Signed-off-by: Christian König Link: https://patchwork.freedesktop.org/patch/msgid/20220819072834.17888-1-jeffy.chen@rock-chips.com

drm/gem: Properly annotate WW context on drm_gem_lock_reservations() error

2022-08-09T16:43:28+00:00

Use ww_acquire_fini() in the error code paths. Otherwise lockdep thinks that lock is held when lock's memory is freed after the drm_gem_lock_reservations() error. The ww_acquire_context needs to be annotated as "released", which fixes the noisy "WARNING: held lock freed!" splat of VirtIO-GPU driver with CONFIG_DEBUG_MUTEXES=y and enabled lockdep. Cc: stable@vger.kernel.org Fixes: 7edc3e3b975b5 ("drm: Add helpers for locking an array of BO reservations.") Reviewed-by: Thomas Hellström Reviewed-by: Christian König Signed-off-by: Dmitry Osipenko Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220630200405.1883897-2-dmitry.osipenko@collabora.com

dma-buf: add enum dma_resv_usage v4

2022-04-07T10:53:53+00:00

This change adds the dma_resv_usage enum and allows us to specify why a dma_resv object is queried for its containing fences. Additional to that a dma_resv_usage_rw() helper function is added to aid retrieving the fences for a read or write userspace submission. This is then deployed to the different query functions of the dma_resv object and all of their users. When the write paratermer was previously true we now use DMA_RESV_USAGE_WRITE and DMA_RESV_USAGE_READ otherwise. v2: add KERNEL/OTHER in separate patch v3: some kerneldoc suggestions by Daniel v4: some more kerneldoc suggestions by Daniel, fix missing cases lost in the rebase pointed out by Bas. Signed-off-by: Christian König Reviewed-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220407085946.744568-2-christian.koenig@amd.com

Merge drm/drm-next into drm-misc-next

2022-04-05T09:06:58+00:00

Let's start the 5.19 development cycle. Signed-off-by: Maxime Ripard

drm/gem: Delete gem array fencing helpers

2022-04-04T14:46:15+00:00

Integrated into the scheduler now and all users converted over. v2: Rebased over changes from König. Acked-by: Christian König Signed-off-by: Daniel Vetter Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Thomas Zimmermann Cc: David Airlie Cc: Daniel Vetter Cc: Sumit Semwal Cc: "Christian König" Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Link: https://patchwork.freedesktop.org/patch/msgid/20220331204651.2699107-3-daniel.vetter@ffwll.ch

Merge tag 'drm-misc-next-2022-02-23' of git://anongit.freedesktop.org/drm/drm-misc into drm-next

2022-02-24T19:50:18+00:00

drm-misc-next for v5.18: UAPI Changes: Cross-subsystem Changes: - Split out panel-lvds and lvds dt bindings . - Put yes/no on/off disabled/enabled strings in linux/string_helpers.h and use it in drivers and tomoyo. - Clarify dma_fence_chain and dma_fence_array should never include eachother. - Flatten chains in syncobj's. - Don't double add in fbdev/defio when page is already enlisted. - Don't sort deferred-I/O pages by default in fbdev. Core Changes: - Fix missing pm_runtime_put_sync in bridge. - Set modifier support to only linear fb modifier if drivers don't advertise support. - As a result, we remove allow_fb_modifiers. - Add missing clear for EDID Deep Color Modes in drm_reset_display_info. - Assorted documentation updates. - Warn once in drm_clflush if there is no arch support. - Add missing select for dp helper in drm_panel_edp. - Assorted small fixes. - Improve fb-helper's clipping handling. - Don't dump shmem mmaps in a core dump. - Add accounting to ttm resource manager, and use it in amdgpu. - Allow querying the detected eDP panel through debugfs. - Add helpers for xrgb8888 to 8 and 1 bits gray. - Improve drm's buddy allocator. - Add selftests for the buddy allocator. Driver Changes: - Add support for nomodeset to a lot of drm drivers. - Use drm_module_*_driver in a lot of drm drivers. - Assorted small fixes to bridge/lt9611, v3d, vc4, vmwgfx, mxsfb, nouveau, bridge/dw-hdmi, panfrost, lima, ingenic, sprd, bridge/anx7625, ti-sn65dsi86. - Add bridge/it6505. - Create DP and DVI-I connectors in ast. - Assorted nouveau backlight fixes. - Rework amdgpu reset handling. - Add dt bindings for ingenic,jz4780-dw-hdmi. - Support reading edid through aux channel in ingenic. - Add a drm driver for Solomon SSD130x OLED displays. - Add simple support for sharp LQ140M1JW46. - Add more panels to nt35560. Signed-off-by: Dave Airlie From: Maarten Lankhorst Link: https://patchwork.freedesktop.org/patch/msgid/686ec871-e77f-c230-22e5-9e3bb80f064a@linux.intel.com