Commit 7bfaa160 authored by Xiaogang Chen's avatar Xiaogang Chen Committed by Alex Deucher
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drm/amdkfd: fix some race conditions in vram buffer alloc/free of svm code 



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: default avatarXiaogang.Chen <xiaogang.chen@amd.com>
Reviewed-by: default avatarFelix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 101b8104

drivers/gpu/drm/amd/amdkfd/kfd_svm.c

+4 −4
Original line number Diff line number Diff line
@@ -504,11 +504,11 @@ 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;

}