* [PATCH 6.12 212/215] drm/amdgpu: fix zero-size GDS range init on RDNA4
[not found] <20260504135130.169210693@linuxfoundation.org>
@ 2026-05-04 13:53 ` Greg Kroah-Hartman
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From: Greg Kroah-Hartman @ 2026-05-04 13:53 UTC (permalink / raw)
To: stable
Cc: Greg Kroah-Hartman, patches, Arjan van de Ven, Alex Deucher,
Christian König, amd-gfx, dri-devel, linux-kernel
6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Arjan van de Ven <arjan@linux.intel.com>
commit 095a8b0ad3c3b5cdc3850d961adb8a8f735220bb upstream.
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 <arjan@linux.intel.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 5719ce5865279cad4fd5f01011fe037168503f2d)
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 3 +++
1 file changed, 3 insertions(+)
--- 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(struc
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);
}
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