CVE-2026-52965drm/ttm: Fix ttm_bo_swapout() infinite LRU walk on swapout failure

Official description

In the Linux kernel, the following vulnerability has been resolved: 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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/060f8f3020516d71bc4d6159d4d0beef85606a74
• https://git.kernel.org/stable/c/0124a09e3e5f5f6080efe9663b27af27933f8382
• https://git.kernel.org/stable/c/b2ed01e7ad3de80333e9b962a44024b094bc0b2b