Re: [PATCH v8 4/9] drm/ttm: Add ttm_bo_kmap_try_from_panic()

Re: [PATCH v8 4/9] drm/ttm: Add ttm_bo_kmap_try_from_panic()

[kernel test robot]

Hi Jocelyn,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 7247efca0dcbc8ac6147db9200ed1549c0662465]

url:    https://github.com/intel-lab-lkp/linux/commits/Jocelyn-Falempe/drm-i915-fbdev-Add-intel_fbdev_get_map/20250606-200804
base:   7247efca0dcbc8ac6147db9200ed1549c0662465
patch link:    https://lore.kernel.org/r/20250606120519.753928-5-jfalempe%40redhat.com
patch subject: [PATCH v8 4/9] drm/ttm: Add ttm_bo_kmap_try_from_panic()
config: x86_64-buildonly-randconfig-001-20250607 (https://download.01.org/0day-ci/archive/20250607/202506070340.P5oZoRwh-lkp@intel.com/config)
compiler: clang version 20.1.2 (https://github.com/llvm/llvm-project 58df0ef89dd64126512e4ee27b4ac3fd8ddf6247)
rustc: rustc 1.78.0 (9b00956e5 2024-04-29)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250607/202506070340.P5oZoRwh-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202506070340.P5oZoRwh-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/gpu/drm/ttm/ttm_bo_util.c:381: warning: Cannot understand  *
    on line 381 - I thought it was a doc line


vim +381 drivers/gpu/drm/ttm/ttm_bo_util.c

   379	
   380	/**
 > 381	 *
   382	 * ttm_bo_kmap_try_from_panic
   383	 *
   384	 * @bo: The buffer object
   385	 * @page: The page to map
   386	 *
   387	 * Sets up a kernel virtual mapping using kmap_local_page_try_from_panic().
   388	 * This can safely be called from the panic handler, if you make sure the bo
   389	 * is the one being displayed, so is properly allocated, and won't be modified.
   390	 *
   391	 * Returns the vaddr, that you can use to write to the bo, and that you should
   392	 * pass to kunmap_local() when you're done with this page, or NULL if the bo
   393	 * is in iomem.
   394	 */
   395	void *ttm_bo_kmap_try_from_panic(struct ttm_buffer_object *bo, unsigned long page)
   396	{
   397		if (page + 1 > PFN_UP(bo->resource->size))
   398			return NULL;
   399	
   400		if (!bo->resource->bus.is_iomem && bo->ttm->pages && bo->ttm->pages[page])
   401			return kmap_local_page_try_from_panic(bo->ttm->pages[page]);
   402	
   403		return NULL;
   404	}
   405	EXPORT_SYMBOL(ttm_bo_kmap_try_from_panic);
   406	

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https://github.com/intel/lkp-tests/wiki