Re: Re: [PATCH] dcache: add fs.dentry-limit sysctl with negative-first reaper

[Stafford Horne]

On Sat, May 16, 2026 at 08:55:16AM +0200, Horst Birthelmer wrote:
> On Fri, May 15, 2026 at 11:09:54PM +0800, kernel test robot wrote:
> > Hi Horst,
> > 
> > kernel test robot noticed the following build errors:
> > 
> > [auto build test ERROR on 5d6919055dec134de3c40167a490f33c74c12581]
> > 
> > url:    https://github.com/intel-lab-lkp/linux/commits/Horst-Birthelmer/dcache-add-fs-dentry-limit-sysctl-with-negative-first-reaper/20260515-154600
> > base:   5d6919055dec134de3c40167a490f33c74c12581
> > patch link:    https://lore.kernel.org/r/20260514-limit-dentries-cache-v1-1-431b9eb0c530%40ddn.com
> > patch subject: [PATCH] dcache: add fs.dentry-limit sysctl with negative-first reaper
> > config: openrisc-randconfig-r073-20260515 (https://download.01.org/0day-ci/archive/20260515/202605152333.0pOd2zJR-lkp@xxxxxxxxx/config)
> > compiler: or1k-linux-gcc (GCC) 10.5.0
> > smatch: v0.5.0-9185-gbcc58b9c
> > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260515/202605152333.0pOd2zJR-lkp@xxxxxxxxx/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@xxxxxxxxx>
> > | Closes: https://lore.kernel.org/oe-kbuild-all/202605152333.0pOd2zJR-lkp@xxxxxxxxx/
> > 
> > All errors (new ones prefixed by >>):
> > 
> >    fs/dcache.c: In function 'dentry_limit_worker_fn':
> > >> fs/dcache.c:1474:7: error: implicit declaration of function 'get_nr_dentry'; did you mean 'retain_dentry'? [-Werror=implicit-function-declaration]
> >     1474 |  nr = get_nr_dentry();
> >          |       ^~~~~~~~~~~~~
> >          |       retain_dentry
> >    cc1: some warnings being treated as errors
> > 
> > 
> > vim +1474 fs/dcache.c
> > 
> ...
> > 
> > --
> > 0-DAY CI Kernel Test Service
> > https://github.com/intel/lkp-tests/wiki
> 
> This is puzzling to me get_nr_dentry() is defined in line 178 in the same file and first used in line 209 
> and has been there since 2013.
> 
> Builds fine applied to tag v7.1-rc3 and to the current master with gcc and clang.

Hi

They are protected in:

#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)

With #endif on line 247.

In the rand config as least I see:
 # CONFIG_PROC_FS is not set

-Stafford