From 70612d0e121e55ea3c057c526bf7374da41aa2f0 Mon Sep 17 00:00:00 2001 From: Lyude Paul Date: Tue, 5 Jan 2021 12:45:05 +0100 Subject: [PATCH] drm/ttm: Remove pinned bos from LRU in ttm_bo_move_to_lru_tail() v2 MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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. v2 (chk): reduce to only the fixing one liner since we always want to call the callback whenever we would move on the LRU. Fixes: 3d1a88e1051f ("drm/ttm: cleanup LRU handling further") Cc: Dave Airlie Reviewed-by: Christian König Signed-off-by: Lyude Paul Signed-off-by: Christian König Link: https://patchwork.freedesktop.org/patch/msgid/20210105114505.38210-1-christian.koenig@amd.com --- drivers/gpu/drm/ttm/ttm_bo.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index 31e8b3da5563..b65f4b12f986 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -138,8 +138,10 @@ void ttm_bo_move_to_lru_tail(struct ttm_buffer_object *bo, dma_resv_assert_held(bo->base.resv); - if (bo->pin_count) + 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]); -- 2.49.0