Am 05.01.21 um 00:13 schrieb Lyude Paul:
Recently a regression was introduced which caused TTM's buffer eviction to
attempt to evict already-pinned BOs, causing issues with buffer eviction
under memory pressure along with suspend/resume:
nouveau 0000:1f:00.0: DRM: evicting buffers...
nouveau 0000:1f:00.0: DRM: Moving pinned object 00000000c428c3ff!
nouveau 0000:1f:00.0: fifo: fault 00 [READ] at 0000000000200000 engine 04
[BAR1] client 07 [HUB/HOST_CPU] reason 02 [PTE] on channel -1 [00ffeaa000
unknown]
nouveau 0000:1f:00.0: fifo: DROPPED_MMU_FAULT 00001000
nouveau 0000:1f:00.0: fifo: fault 01 [WRITE] at 0000000000020000 engine
0c [HOST6] client 07 [HUB/HOST_CPU] reason 02 [PTE] on channel 1
[00ffb28000 DRM]
nouveau 0000:1f:00.0: fifo: channel 1: killed
nouveau 0000:1f:00.0: fifo: runlist 0: scheduled for recovery
[TTM] Buffer eviction failed
nouveau 0000:1f:00.0: DRM: waiting for kernel channels to go idle...
nouveau 0000:1f:00.0: DRM: failed to idle channel 1 [DRM]
nouveau 0000:1f:00.0: DRM: resuming display...
After some bisection and investigation, it appears this resulted from the
recent changes to ttm_bo_move_to_lru_tail(). Previously when a buffer was
pinned, the buffer would be removed from the LRU once ttm_bo_unreserve
to maintain the LRU list when pinning or unpinning BOs. However, since:
commit 3d1a88e1051f ("drm/ttm: cleanup LRU handling further")
We've been exiting from ttm_bo_move_to_lru_tail() at the very beginning of
the function if the bo we're looking at is pinned, resulting in the pinned
BO never getting removed from the lru and as a result - causing issues when
it eventually becomes time for eviction.
So, let's fix this by calling ttm_bo_del_from_lru() from
ttm_bo_move_to_lru_tail() in the event that we're dealing with a pinned
buffer. As well, add back the hunks in ttm_bo_del_from_lru() that were
removed which checked whether we want to call
bdev->driver->del_from_lru_notify() or not. We do this last part to avoid
calling the hook when the bo in question was already removed from the LRU.
Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
Fixes: 3d1a88e1051f ("drm/ttm: cleanup LRU handling further")
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Dave Airlie <airlied@xxxxxxxxxx>
I was already working on a fix as well, but you have been faster than me :)
Reviewed-by: Christian König <christian.koenig@xxxxxxx>
Going to pick this up for drm-misc-next or drm-misc-fixes in a few minutes.
Thanks,
Christian.
---
drivers/gpu/drm/ttm/ttm_bo.c | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 31e8b3da5563..0f373b78e7fa 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -113,11 +113,18 @@ static struct kobj_type ttm_bo_glob_kobj_type = {
static void ttm_bo_del_from_lru(struct ttm_buffer_object *bo)
{
struct ttm_bo_device *bdev = bo->bdev;
+ bool notify = false;
- list_del_init(&bo->swap);
- list_del_init(&bo->lru);
+ if (!list_empty(&bo->swap)) {
+ notify = true;
+ list_del_init(&bo->swap);
+ }
+ if (!list_empty(&bo->lru)) {
+ notify = true;
+ list_del_init(&bo->lru);
+ }
- if (bdev->driver->del_from_lru_notify)
+ if (notify && bdev->driver->del_from_lru_notify)
bdev->driver->del_from_lru_notify(bo);
}
@@ -138,8 +145,13 @@ void ttm_bo_move_to_lru_tail(struct ttm_buffer_object *bo,
dma_resv_assert_held(bo->base.resv);
- if (bo->pin_count)
+ /* Pinned bos will have been added to the LRU before they were pinned, so make sure we
+ * always remove them here
+ */
+ if (bo->pin_count) {
+ ttm_bo_del_from_lru(bo);
return;
+ }
man = ttm_manager_type(bdev, mem->mem_type);
list_move_tail(&bo->lru, &man->lru[bo->priority]);
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