1a545ed74b
Currently, unload pvc driver will generate a null dereference and the call stack is as below. [ 4850.618000] Call Trace: [ 4850.620740] <TASK> [ 4850.623134] ttm_bo_cleanup_memtype_use+0x3f/0x50 [ttm] [ 4850.628661] ttm_bo_release+0x154/0x2c0 [ttm] [ 4850.633317] ? drm_buddy_fini+0x62/0x80 [drm_buddy] [ 4850.638487] ? __kmem_cache_free+0x27d/0x2c0 [ 4850.643054] ttm_bo_put+0x38/0x60 [ttm] [ 4850.647190] xe_gem_object_free+0x1f/0x30 [xe] [ 4850.651945] drm_gem_object_free+0x1e/0x30 [drm] [ 4850.656904] ggtt_fini_noalloc+0x9d/0xe0 [xe] [ 4850.661574] drm_managed_release+0xb5/0x150 [drm] [ 4850.666617] drm_dev_release+0x30/0x50 [drm] [ 4850.671209] devm_drm_dev_init_release+0x3c/0x60 [drm] There are a couple issues, but the main one is due to TTM has only one TTM_PL_TT region, but since pvc has 2 tiles and tries to setup 1 TTM_PL_TT each tile. The second will overwrite the first one. During unload time, the first tile will reset the TTM_PL_TT manger and when the second tile is trying to free Bo and it will generate the null reference since the TTM manage is already got reset to 0. The fix is to use one global TTM_PL_TT manager. v2: make gtt mgr global and change the name to sys_mgr Cc: Stuart Summers <stuart.summers@intel.com> Cc: Matthew Brost <matthew.brost@intel.com> Cc: Vivi, Rodrigo <rodrigo.vivi@intel.com> Signed-off-by: Bruce Chang <yu.bruce.chang@intel.com> Reviewed-by: Matthew Brost <matthew.brost@intel.com> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.