This is a note to let you know that I've just added the patch titled
drm/amdkfd: fix some race conditions in vram buffer alloc/free of svm code
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-amdkfd-fix-some-race-conditions-in-vram-buffer-a.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 7f25b66c729778b9fb322b1f8e0768588f160945
Author: Xiaogang Chen <xiaogang.chen@xxxxxxx>
Date: Wed Sep 20 11:02:51 2023 -0500
drm/amdkfd: fix some race conditions in vram buffer alloc/free of svm code
[ Upstream commit 7bfaa160caed8192f8262c4638f552cad94bcf5a ]
This patch fixes:
1: ref number of prange's svm_bo got decreased by an async call from hmm. When
wait svm_bo of prange got released we shoul also wait prang->svm_bo become NULL,
otherwise prange->svm_bo may be set to null after allocate new vram buffer.
2: During waiting svm_bo of prange got released in a while loop should reschedule
current task to give other tasks oppotunity to run, specially the the workque
task that handles svm_bo ref release, otherwise we may enter to softlock.
Signed-off-by: Xiaogang.Chen <xiaogang.chen@xxxxxxx>
Reviewed-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
index bb16b795d1bc2..bb65a99439802 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
@@ -495,11 +495,11 @@ svm_range_validate_svm_bo(struct kfd_node *node, struct svm_range *prange)
/* We need a new svm_bo. Spin-loop to wait for concurrent
* svm_range_bo_release to finish removing this range from
- * its range list. After this, it is safe to reuse the
- * svm_bo pointer and svm_bo_list head.
+ * its range list and set prange->svm_bo to null. After this,
+ * it is safe to reuse the svm_bo pointer and svm_bo_list head.
*/
- while (!list_empty_careful(&prange->svm_bo_list))
- ;
+ while (!list_empty_careful(&prange->svm_bo_list) || prange->svm_bo)
+ cond_resched();
return false;
}
