From: Arjan van de Ven Date: Mon, 20 Apr 2026 21:57:15 +0000 (-0700) Subject: drm/amdgpu: fix zero-size GDS range init on RDNA4 X-Git-Tag: v7.1-rc2~7^2~1^2~48 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=095a8b0ad3c3b5cdc3850d961adb8a8f735220bb;p=thirdparty%2Fkernel%2Fstable.git drm/amdgpu: fix zero-size GDS range init on RDNA4 RDNA4 (GFX 12) hardware removes the GDS, GWS, and OA on-chip memory resources. The gfx_v12_0 initialisation code correctly leaves adev->gds.gds_size, adev->gds.gws_size, and adev->gds.oa_size at zero to reflect this. amdgpu_ttm_init() unconditionally calls amdgpu_ttm_init_on_chip() for each of these resources regardless of size. When the size is zero, amdgpu_ttm_init_on_chip() forwards the call to ttm_range_man_init(), which calls drm_mm_init(mm, 0, 0). drm_mm_init() immediately fires DRM_MM_BUG_ON(start + size <= start) -- trivially true when size is zero -- crashing the kernel during modprobe of amdgpu on an RX 9070 XT. Guard against this by returning 0 early from amdgpu_ttm_init_on_chip() when size_in_page is zero. This skips TTM resource manager registration for hardware resources that are absent, without affecting any other GPU type. DRM_MM_BUG_ON() only asserts if CONFIG_DRM_DEBUG_MM is enabled in the kernel config. This is apparently rarely enabled as these chips have been in the market for over a year and this issue was only reported now. Link: https://lore.kernel.org/all/bug-221376-2300@https.bugzilla.kernel.org%2F/ Link: https://bugzilla.kernel.org/show_bug.cgi?id=221376 Oops-Analysis: http://oops.fenrus.org/reports/bugzilla.korg/221376/report.html Assisted-by: GitHub Copilot:Claude Sonnet 4.6 linux-kernel-oops-x86. Signed-off-by: Arjan van de Ven Cc: Alex Deucher Cc: "Christian König" Cc: amd-gfx@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Alex Deucher (cherry picked from commit 5719ce5865279cad4fd5f01011fe037168503f2d) Cc: stable@vger.kernel.org --- diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c index 0dc68fb9d88e5..3d2e00efc7415 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c @@ -75,6 +75,9 @@ static int amdgpu_ttm_init_on_chip(struct amdgpu_device *adev, unsigned int type, uint64_t size_in_page) { + if (!size_in_page) + return 0; + return ttm_range_man_init(&adev->mman.bdev, type, false, size_in_page); }