linux-kernel - [PATCH] drm/nouveau: Add __GFP_NOFAIL for DSM buffer allocation in r535_disp

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Message-Id: <20251106095735.788100-1-liqiang01@kylinos.cn>
Date: Thu,  6 Nov 2025 17:57:35 +0800
From: Li Qiang <liqiang01@...inos.cn>
To: lyude@...hat.com,
	dakr@...nel.org,
	maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	airlied@...il.com,
	simona@...ll.ch
Cc: dri-devel@...ts.freedesktop.org,
	nouveau@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Li Qiang <liqiang01@...inos.cn>
Subject: [PATCH] drm/nouveau: Add __GFP_NOFAIL for DSM buffer allocation in r535_disp_oneinit()

acpi_evaluate_dsm() expects a valid buffer pointer for the DSM argument.
The current code uses kmalloc() without checking its return value, which
may lead to a NULL pointer dereference under memory pressure.

Since this buffer is small and there is no recovery path available here,
use __GFP_NOFAIL to guarantee allocation success and avoid potential
kernel crashes.

Fixes: 9e99444490238 ("drm/nouveau/disp/r535: initial support")
Signed-off-by: Li Qiang <liqiang01@...inos.cn>
---
 drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c
index 6e63df816d85..f55ff5dea1c5 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c
@@ -1585,7 +1585,8 @@ r535_disp_oneinit(struct nvkm_disp *disp)
 					union acpi_object argv4 = {
 						.buffer.type    = ACPI_TYPE_BUFFER,
 						.buffer.length  = sizeof(ctrl->backLightData),
-						.buffer.pointer = kmalloc(argv4.buffer.length, GFP_KERNEL),
+						.buffer.pointer = kmalloc(argv4.buffer.length,
+								GFP_KERNEL | __GFP_NOFAIL),
 					}, *obj;
 
 					obj = acpi_evaluate_dsm(handle, nbci ? &NBCI_DSM_GUID : &NVHG_DSM_GUID,
-- 
2.25.1