[RFC PATCH] drm/ttm: Do page counting after populate callback succeed

[xinhui pan]

Amdgpu set SG flag in populate callback. So TTM still count pages in SG
BO.
One easy way to fix this is lets count pages after populate callback.

We hit one issue that amdgpu alloc many SG BOs, but TTM try to do swap
again and again even if swapout does not swap SG BOs at all.

Signed-off-by: xinhui pan <xinhui....@amd.com>
---
 drivers/gpu/drm/ttm/ttm_tt.c | 32 +++++++++++++-------------------
 1 file changed, 13 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
index a1a25410ec74..4fa0a8cd71c0 100644
--- a/drivers/gpu/drm/ttm/ttm_tt.c
+++ b/drivers/gpu/drm/ttm/ttm_tt.c
@@ -317,13 +317,6 @@ int ttm_tt_populate(struct ttm_device *bdev,
        if (ttm_tt_is_populated(ttm))
                return 0;
 
-       if (!(ttm->page_flags & TTM_PAGE_FLAG_SG)) {
-               atomic_long_add(ttm->num_pages, &ttm_pages_allocated);
-               if (bdev->pool.use_dma32)
-                       atomic_long_add(ttm->num_pages,
-                                       &ttm_dma32_pages_allocated);
-       }
-
        while (atomic_long_read(&ttm_pages_allocated) > ttm_pages_limit ||
               atomic_long_read(&ttm_dma32_pages_allocated) >
               ttm_dma32_pages_limit) {
@@ -342,6 +335,13 @@ int ttm_tt_populate(struct ttm_device *bdev,
        if (ret)
                goto error;
 
+       if (!(ttm->page_flags & TTM_PAGE_FLAG_SG)) {
+               atomic_long_add(ttm->num_pages, &ttm_pages_allocated);
+               if (bdev->pool.use_dma32)
+                       atomic_long_add(ttm->num_pages,
+                                       &ttm_dma32_pages_allocated);
+       }
+
        ttm_tt_add_mapping(bdev, ttm);
        ttm->page_flags |= TTM_PAGE_FLAG_PRIV_POPULATED;
        if (unlikely(ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)) {
@@ -355,12 +355,6 @@ int ttm_tt_populate(struct ttm_device *bdev,
        return 0;
 
 error:
-       if (!(ttm->page_flags & TTM_PAGE_FLAG_SG)) {
-               atomic_long_sub(ttm->num_pages, &ttm_pages_allocated);
-               if (bdev->pool.use_dma32)
-                       atomic_long_sub(ttm->num_pages,
-                                       &ttm_dma32_pages_allocated);
-       }
        return ret;
 }
 EXPORT_SYMBOL(ttm_tt_populate);
@@ -384,12 +378,6 @@ void ttm_tt_unpopulate(struct ttm_device *bdev, struct 
ttm_tt *ttm)
        if (!ttm_tt_is_populated(ttm))
                return;
 
-       ttm_tt_clear_mapping(ttm);
-       if (bdev->funcs->ttm_tt_unpopulate)
-               bdev->funcs->ttm_tt_unpopulate(bdev, ttm);
-       else
-               ttm_pool_free(&bdev->pool, ttm);
-
        if (!(ttm->page_flags & TTM_PAGE_FLAG_SG)) {
                atomic_long_sub(ttm->num_pages, &ttm_pages_allocated);
                if (bdev->pool.use_dma32)
@@ -397,6 +385,12 @@ void ttm_tt_unpopulate(struct ttm_device *bdev, struct 
ttm_tt *ttm)
                                        &ttm_dma32_pages_allocated);
        }
 
+       ttm_tt_clear_mapping(ttm);
+       if (bdev->funcs->ttm_tt_unpopulate)
+               bdev->funcs->ttm_tt_unpopulate(bdev, ttm);
+       else
+               ttm_pool_free(&bdev->pool, ttm);
+
        ttm->page_flags &= ~TTM_PAGE_FLAG_PRIV_POPULATED;
 }
 
-- 
2.25.1