[PATCH] drm/amdkfd: Change error handling at prange update in svm_range_set_attr

[Chen, Xiaogang]

[AMD Official Use Only - AMD Internal Distribution Only]

Ping

-----Original Message-----
From: Xiaogang.Chen <xiaogang.chen at amd.com>
Sent: Friday, January 31, 2025 10:59 AM
To: amd-gfx at lists.freedesktop.org
Cc: Chen, Xiaogang <Xiaogang.Chen at amd.com>
Subject: [PATCH] drm/amdkfd: Change error handling at prange update in svm_range_set_attr

From: Xiaogang Chen <xiaogang.chen at amd.com>

When register a vm range at svm the added vm range may be split into multiple subranges and/or existing pranges got spitted. The new pranges need validated and mapped. This patch changes error handling for pranges that fail updating:

1: free prange resources and remove it from svms if its updating fails as it will not be used.
2: return -EAGAIN when all pranges at update_list need redo valid/map, otherwise return no -EAGAIN error to user space to indicate failure. That removes unnecessary retries.

Signed-off-by: Xiaogang Chen <xiaogang.chen at amd.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 27 +++++++++++++++++++++++----
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
index e32e19196f6b..455cb98bf16a 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
@@ -3716,8 +3716,19 @@ svm_range_set_attr(struct kfd_process *p, struct mm_struct *mm,

 out_unlock_range:
                mutex_unlock(&prange->migrate_mutex);
-               if (r)
-                       ret = r;
+               /* this prange cannot be migraed, valid or map */
+               if (r) {
+                       /* free this prange resources, remove it from svms */
+                       svm_range_unlink(prange);
+                       svm_range_remove_notifier(prange);
+                       svm_range_free(prange, false);
+
+                       /* ret got update when any r != -EAGAIN;
+                        * return -EAGAIN when all pranges at update_list
+                        * need redo valid/map */
+                       if (r != -EAGAIN || !ret)
+                               ret = r;
+               }
        }

        list_for_each_entry(prange, &remap_list, update_list) { @@ -3729,8 +3740,16 @@ svm_range_set_attr(struct kfd_process *p, struct mm_struct *mm,
                if (r)
                        pr_debug("failed %d on remap svm range\n", r);
                mutex_unlock(&prange->migrate_mutex);
-               if (r)
-                       ret = r;
+
+               if (r) {
+                       /* remove this prange */
+                       svm_range_unlink(prange);
+                       svm_range_remove_notifier(prange);
+                       svm_range_free(prange, false);
+
+                       if (r != -EAGAIN || !ret)
+                               ret = r;
+               }
        }

        dynamic_svm_range_dump(svms);
--
2.25.1