diff options
| author | Thomas Hellström <thomas.hellstrom@linux.intel.com> | 2026-04-28 11:44:42 +0200 |
|---|---|---|
| committer | Thomas Hellström <thomas.hellstrom@linux.intel.com> | 2026-05-08 17:19:44 +0200 |
| commit | b2ed01e7ad3de80333e9b962a44024b094bc0b2b (patch) | |
| tree | bd6597b45529d5f017b059af984a4ab5a0cd7256 /drivers | |
| parent | 459d75523b71c0ec254d153d8850d0b7008af396 (diff) | |
drm/ttm: Fix ttm_bo_swapout() infinite LRU walk on swapout failure
When ttm_tt_swapout() fails, the current code calls
ttm_resource_add_bulk_move() followed by ttm_resource_move_to_lru_tail()
to restore the resource's bulk_move membership.
However, ttm_resource_move_to_lru_tail() places the resource at the tail
of the LRU list which, relative to the walk cursor's hitch node (placed
immediately after the resource when it was yielded), puts the resource
*in front of the* the hitch. The next list_for_each_entry_continue() from
the hitch finds the same resource again, causing an infinite loop.
Fix by deferring del_bulk_move to the success path only.
On the success path, TTM_TT_FLAG_SWAPPED has just been set by
ttm_tt_swapout() but the resource is still tracked in the bulk_move range,
so ttm_resource_del_bulk_move()'s !ttm_resource_unevictable() guard would
incorrectly skip the removal. Introduce
ttm_resource_del_bulk_move_unevictable() which bypasses that guard.
Reported-by: Jatin Kataria <jkataria@netflix.com>
Fixes: fc5d96670eb2 ("drm/ttm: Move swapped objects off the manager's LRU list")
Cc: Christian König <christian.koenig@amd.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: <dri-devel@lists.freedesktop.org>
Cc: <stable@vger.kernel.org> # v6.13+
Assisted-by: GitHub_Copilot:claude-sonnet-4.6
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Tested-by: Boqun Feng <boqun@kernel.org>
Link: https://patch.msgid.link/20260428094442.16985-1-thomas.hellstrom@linux.intel.com
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/gpu/drm/ttm/ttm_bo.c | 16 | ||||
| -rw-r--r-- | drivers/gpu/drm/ttm/ttm_resource.c | 13 |
2 files changed, 19 insertions, 10 deletions
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index d85f0a37ac35..293401705542 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -1177,17 +1177,13 @@ ttm_bo_swapout_cb(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo) bdev->funcs->swap_notify(bo); if (ttm_tt_is_populated(tt)) { - spin_lock(&bdev->lru_lock); - ttm_resource_del_bulk_move(bo->resource, bo); - spin_unlock(&bdev->lru_lock); - ret = ttm_tt_swapout(bdev, tt, swapout_walk->gfp_flags); - - spin_lock(&bdev->lru_lock); - if (ret) - ttm_resource_add_bulk_move(bo->resource, bo); - ttm_resource_move_to_lru_tail(bo->resource); - spin_unlock(&bdev->lru_lock); + if (!ret) { + spin_lock(&bdev->lru_lock); + ttm_resource_del_bulk_move_unevictable(bo->resource, bo); + ttm_resource_move_to_lru_tail(bo->resource); + spin_unlock(&bdev->lru_lock); + } } out: diff --git a/drivers/gpu/drm/ttm/ttm_resource.c b/drivers/gpu/drm/ttm/ttm_resource.c index 9f36631d48b6..0e5f1582f13d 100644 --- a/drivers/gpu/drm/ttm/ttm_resource.c +++ b/drivers/gpu/drm/ttm/ttm_resource.c @@ -292,6 +292,19 @@ void ttm_resource_del_bulk_move(struct ttm_resource *res, ttm_lru_bulk_move_del(bo->bulk_move, res); } +/* + * Remove a resource from its bulk_move, bypassing the unevictable check. + * Use only when the resource is known to still be tracked in the range despite + * the BO having just become unevictable; asserts that this is the case. + */ +void ttm_resource_del_bulk_move_unevictable(struct ttm_resource *res, + struct ttm_buffer_object *bo) +{ + WARN_ON_ONCE(!ttm_resource_unevictable(res, bo)); + if (bo->bulk_move) + ttm_lru_bulk_move_del(bo->bulk_move, res); +} + /* Move a resource to the LRU or bulk tail */ void ttm_resource_move_to_lru_tail(struct ttm_resource *res) { |