Re: [PATCH v5 06/12] drm/i915: Use huge tmpfs mountpoint helpers

[Boris Brezillon <boris.brezillon@collabora.com>]

On Wed, 22 Oct 2025 11:25:10 +0800
kernel test robot <lkp@intel.com> wrote:

> Hi Loïc,
> 
> kernel test robot noticed the following build errors:
> 
> [auto build test ERROR on next-20251021]
> [also build test ERROR on v6.18-rc2]
> [cannot apply to akpm-mm/mm-everything drm-misc/drm-misc-next linus/master v6.18-rc2 v6.18-rc1 v6.17]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Lo-c-Molinari/drm-shmem-helper-Simplify-page-offset-calculation-in-fault-handler/20251021-193355
> base:   next-20251021
> patch link:    https://lore.kernel.org/r/20251021113049.17242-7-loic.molinari%40collabora.com
> patch subject: [PATCH v5 06/12] drm/i915: Use huge tmpfs mountpoint helpers
> config: x86_64-randconfig-003-20251022 (https://download.01.org/0day-ci/archive/20251022/202510221301.wU3TSqMg-lkp@intel.com/config)
> compiler: gcc-13 (Debian 13.3.0-16) 13.3.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251022/202510221301.wU3TSqMg-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/202510221301.wU3TSqMg-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
>    drivers/gpu/drm/i915/gem/i915_gem_shmem.c: In function '__create_shmem':
> >> drivers/gpu/drm/i915/gem/i915_gem_shmem.c:511:59: error: 'struct drm_device' has no member named 'huge_mnt'  
>      511 |                 filp = shmem_file_setup_with_mnt(i915->drm.huge_mnt, "i915",
>          |                                                           ^
> 
> 
> vim +511 drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> 
>    486	
>    487	static int __create_shmem(struct drm_i915_private *i915,
>    488				  struct drm_gem_object *obj,
>    489				  resource_size_t size)
>    490	{
>    491		unsigned long flags = VM_NORESERVE;
>    492		struct file *filp;
>    493	
>    494		drm_gem_private_object_init(&i915->drm, obj, size);
>    495	
>    496		/* XXX: The __shmem_file_setup() function returns -EINVAL if size is
>    497		 * greater than MAX_LFS_FILESIZE.
>    498		 * To handle the same error as other code that returns -E2BIG when
>    499		 * the size is too large, we add a code that returns -E2BIG when the
>    500		 * size is larger than the size that can be handled.
>    501		 * If BITS_PER_LONG is 32, size > MAX_LFS_FILESIZE is always false,
>    502		 * so we only needs to check when BITS_PER_LONG is 64.
>    503		 * If BITS_PER_LONG is 32, E2BIG checks are processed when
>    504		 * i915_gem_object_size_2big() is called before init_object() callback
>    505		 * is called.
>    506		 */
>    507		if (BITS_PER_LONG == 64 && size > MAX_LFS_FILESIZE)
>    508			return -E2BIG;
>    509	
>    510		if (drm_gem_has_huge_mnt(&i915->drm))
>  > 511			filp = shmem_file_setup_with_mnt(i915->drm.huge_mnt, "i915",  
>    512							 size, flags);

Maybe instead of this drm_gem_has_huge_mnt() (or in addition to), we
should have a drm_gem_get_huge_mnt() helper, so we don't have drivers
dereferencing drm_device::huge_mnt directly and we can get rid of it on
non THP configs.

>    513		else
>    514			filp = shmem_file_setup("i915", size, flags);
>    515		if (IS_ERR(filp))
>    516			return PTR_ERR(filp);
>    517	
>    518		/*
>    519		 * Prevent -EFBIG by allowing large writes beyond MAX_NON_LFS on shmem
>    520		 * objects by setting O_LARGEFILE.
>    521		 */
>    522		if (force_o_largefile())
>    523			filp->f_flags |= O_LARGEFILE;
>    524	
>    525		obj->filp = filp;
>    526		return 0;
>    527	}
>    528	
>