Re: [ebiggers:wip-fsverity 6/8] fs/buffer.c:2280:5: warning: stack frame size (2128) exceeds limit (1024) in '__block_read_full_folio'

["Arnd Bergmann" <arnd@arndb.de>]

On Wed, Oct 5, 2022, at 11:11 AM, kernel test robot wrote:
> tree:   
> https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git 
> wip-fsverity
> head:   06702850f2f281bdd6165c4783a0a15685efbcfd
> commit: dbcfaa162251f84f78105036633f71e91dc3bb8b [6/8] fs/buffer.c: 
> introduce __block_read_full_folio() for ext4
> config: hexagon-randconfig-r041-20221003
> compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 
> 791a7ae1ba3efd6bca96338e10ffde557ba83920)
> reproduce (this is a W=1 build):
>         wget 
> https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross 
> -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # 
> https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git/commit/?id=dbcfaa162251f84f78105036633f71e91dc3bb8b
>         git remote add ebiggers 
> https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git
>         git fetch --no-tags ebiggers wip-fsverity
>         git checkout dbcfaa162251f84f78105036633f71e91dc3bb8b
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 
> O=build_dir ARCH=hexagon SHELL=/bin/bash
>
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
>
> All warnings (new ones prefixed by >>):
>
>>> fs/buffer.c:2280:5: warning: stack frame size (2128) exceeds limit (1024) in '__block_read_full_folio' [-Wframe-larger-than]
>    int __block_read_full_folio(struct folio *folio, loff_t limit,
>        ^

IIRC the conclusion we came to when this last showed up was
that on Hexagon and PowerPC4xx, we want PAGE_SIZE_256KB to
depend on CONFIG_BLOCK being disabled, in order to completely
sidestep this issue. Pages this large should be really rare
anyway, and those platforms tend to run from RAM or MTD flash
rather than using block based file systems.

    Arnd