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On 10/25/2024 8:13 AM, Srinivasan Shanmugam wrote:
The `kfd_get_cu_occupancy` function previously declared a large
`cu_occupancy` array as a local variable, which could lead to stack
overflows due to excessive stack usage. This commit replaces the static
array allocation with dynamic memory allocation using `kcalloc`,
thereby reducing the stack size.
This change avoids the risk of stack overflows in kernel space, in
scenarios where `AMDGPU_MAX_QUEUES` is large. The allocated memory is
freed using `kfree` before the function returns to prevent memory
leaks.
Fixes the below with gcc W=1:
drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_process.c: In function ‘kfd_get_cu_occupancy’:
drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_process.c:322:1: warning: the frame size of 1056 bytes is larger than 1024 bytes [-Wframe-larger-than=]
322 | }
| ^
Fixes: 6fc91266b798 ("drm/amdkfd: Update logic for CU occupancy calculations")
Cc: Harish Kasiviswanathan <Harish.Kasiviswanathan@xxxxxxx>
Cc: Felix Kuehling <felix.kuehling@xxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@xxxxxxx>
Suggested-by: Mukul Joshi <mukul.joshi@xxxxxxx>
---
v4:
- Allocation is moved just before it's needed (Mukul)
drivers/gpu/drm/amd/amdkfd/kfd_process.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index d4aa843aacfd..6bab6fc6a35d 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -271,11 +271,9 @@ static int kfd_get_cu_occupancy(struct attribute *attr, char *buffer)
struct kfd_process *proc = NULL;
struct kfd_process_device *pdd = NULL;
int i;
- struct kfd_cu_occupancy cu_occupancy[AMDGPU_MAX_QUEUES];
+ struct kfd_cu_occupancy *cu_occupancy;
u32 queue_format;
- memset(cu_occupancy, 0x0, sizeof(cu_occupancy));
-
pdd = container_of(attr, struct kfd_process_device, attr_cu_occupancy);
dev = pdd->dev;
if (dev->kfd2kgd->get_cu_occupancy == NULL)
@@ -293,6 +291,10 @@ static int kfd_get_cu_occupancy(struct attribute *attr, char *buffer)
wave_cnt = 0;
max_waves_per_cu = 0;
+ cu_occupancy = kcalloc(AMDGPU_MAX_QUEUES, sizeof(*cu_occupancy), GFP_KERNEL);
+ if (!cu_occupancy)
+ return -ENOMEM;
+
/*
* For GFX 9.4.3, fetch the CU occupancy from the first XCC in the partition.
* For AQL queues, because of cooperative dispatch we multiply the wave count
@@ -318,6 +320,7 @@ static int kfd_get_cu_occupancy(struct attribute *attr, char *buffer)
/* Translate wave count to number of compute units */
cu_cnt = (wave_cnt + (max_waves_per_cu - 1)) / max_waves_per_cu;
+ kfree(cu_occupancy);
return snprintf(buffer, PAGE_SIZE, "%d\n", cu_cnt);
}
