Am 27.05.21 um 17:05 schrieb Thomas Hellström:
On Thu, 2021-05-27 at 17:01 +0200, Thomas Hellström wrote:
On Thu, 2021-05-27 at 16:54 +0200, Christian König wrote:
Am 27.05.21 um 16:19 schrieb Thomas Hellström:
The swapping code was dereference bo->ttm pointers without having
the
dma-resv lock held. Also it might try to swap out unpopulated
bos.
Fix this by moving the bo->ttm dereference until we have the
reservation
lock. Check that the ttm_tt is populated after the swap_notify
callback.
Signed-off-by: Thomas Hellström
<thomas.hellstrom@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/ttm/ttm_bo.c | 16 +++++++++++++++-
drivers/gpu/drm/ttm/ttm_device.c | 8 +++-----
2 files changed, 18 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c
b/drivers/gpu/drm/ttm/ttm_bo.c
index 9f53506a82fc..86213d37657b 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -1163,6 +1163,16 @@ int ttm_bo_swapout(struct
ttm_buffer_object
*bo, struct ttm_operation_ctx *ctx,
if (!ttm_bo_evict_swapout_allowable(bo, ctx, &place,
&locked, NULL))
return -EBUSY;
+ dma_resv_assert_held(bo->base.resv);
+
+ if (!bo->ttm ||
+ bo->ttm->page_flags & TTM_PAGE_FLAG_SG ||
+ bo->ttm->page_flags & TTM_PAGE_FLAG_SWAPPED) {
+ if (locked)
+ dma_resv_unlock(bo->base.resv);
+ return -EBUSY;
+ }
+
if (!ttm_bo_get_unless_zero(bo)) {
if (locked)
dma_resv_unlock(bo->base.resv);
@@ -1215,7 +1225,8 @@ int ttm_bo_swapout(struct ttm_buffer_object
*bo, struct ttm_operation_ctx *ctx,
if (bo->bdev->funcs->swap_notify)
bo->bdev->funcs->swap_notify(bo);
- ret = ttm_tt_swapout(bo->bdev, bo->ttm, gfp_flags);
+ if (ttm_tt_is_populated(bo->ttm))
+ ret = ttm_tt_swapout(bo->bdev, bo->ttm,
gfp_flags);
Exactly that is what I won't recommend. We would try to swap out
the
same BO over and over again with that.
But we wouldn't since the BO is taken off the LRU and never re-added,
In fact, we'd probably might want to take the !bo->ttm bos off the LRU
as well..
No, we don't want to take any BOs of the LRU unless they are pinned.
Adding a TT object or populating it doesn't necessarily put the BO back
to the LRU.
Christian.
/Thomas
