Re: [PATCH] drm/amdkfd: retry after EBUSY is returned from hmm_ranges_get_pages

[Felix Kuehling]

On 2023-08-16 14:44, Alex Sierra wrote:

if hmm_range_get_pages returns EBUSY error during
svm_range_validate_and_map, within the context of a page fault
interrupt. This should retry through svm_range_restore_pages
callback. Therefore we treat this as EAGAIN error instead, and defer
it to restore pages fallback.

Signed-off-by: Alex Sierra <alex.sie...@amd.com>

Reviewed-by: Felix Kuehling <felix.kuehl...@amd.com>

---
  drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 2 ++
  1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c 
b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
index 93609ea42163..3ebd5d99f39e 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
@@ -1685,6 +1685,8 @@ static int svm_range_validate_and_map(struct mm_struct 
*mm,
                WRITE_ONCE(p->svms.faulting_task, NULL);
                if (r) {
                        pr_debug("failed %d to get svm range pages\n", r);
+                       if (r == -EBUSY)
+                               r = -EAGAIN;
                        goto unreserve_out;
                }