Re: [PATCH 1/2] drm/i915: set O_LARGEFILE in __create_shmem()

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Mon, Aug 11, 2025 at 09:30:55AM +0000, 陈涛涛 Taotao Chen wrote:
> From: Taotao Chen <chentaotao@didiglobal.com>
> 
> Without O_LARGEFILE, file->f_op->write_iter calls
> generic_write_check_limits(), which enforces a 2GB (MAX_NON_LFS) limit,
> causing -EFBIG on large writes.
> 
> In shmem_pwrite(), this error is later masked as -EIO due to the error
> handling order, leading to igt failures like gen9_exec_parse(bb-large).
> 
> Set O_LARGEFILE in __create_shmem() to prevent -EFBIG on large writes.
> 
> Reported-by: kernel test robot <oliver.sang@intel.com>
> Closes: https://lore.kernel.org/oe-lkp/202508081029.343192ec-lkp@intel.com
> Fixes: 048832a3f400 ("drm/i915: Refactor shmem_pwrite() to use kiocb and write_iter")
> Signed-off-by: Taotao Chen <chentaotao@didiglobal.com>
> ---
>  drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> index e3d188455f67..2b53aad915f5 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> @@ -514,6 +514,11 @@ static int __create_shmem(struct drm_i915_private *i915,
>  	if (IS_ERR(filp))
>  		return PTR_ERR(filp);
>  
> +	/*
> +	 * Prevent -EFBIG by allowing large writes beyond MAX_NON_LFS on shmem
> +	 * objects by setting O_LARGEFILE.
> +	 */
> +	filp->f_flags |= O_LARGEFILE;

honest question, is it safe to set this here unconditionally?

Cc: Matthew Auld <matthew.auld@intel.com>

>  	obj->filp = filp;
>  	return 0;
>  }
> -- 
> 2.34.1