Re: [PATCH v4] fs: hide names_cachep behind runtime access machinery

[kernel test robot <lkp@intel.com>]

Hi Mateusz,

kernel test robot noticed the following build warnings:

[auto build test WARNING on arnd-asm-generic/master]
[also build test WARNING on linus/master brauner-vfs/vfs.all linux/master v6.18-rc3 next-20251031]
[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/Mateusz-Guzik/fs-hide-names_cachep-behind-runtime-access-machinery/20251030-185523
base:   https://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic.git master
patch link:    https://lore.kernel.org/r/20251030105242.801528-1-mjguzik%40gmail.com
patch subject: [PATCH v4] fs: hide names_cachep behind runtime access machinery
config: i386-randconfig-061-20251031 (https://download.01.org/0day-ci/archive/20251101/202511010440.FLitz9Fi-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251101/202511010440.FLitz9Fi-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/202511010440.FLitz9Fi-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
   fs/d_path.c:195:9: sparse: sparse: context imbalance in 'prepend_path' - wrong count at exit
   fs/d_path.c:359:9: sparse: sparse: context imbalance in '__dentry_path' - wrong count at exit
>> fs/d_path.c:416:22: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
>> fs/d_path.c:416:22: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
   fs/d_path.c:446:9: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
--
>> fs/namei.c:146:18: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
>> fs/namei.c:146:18: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
   fs/namei.c:163:25: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
   fs/namei.c:169:25: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
   fs/namei.c:191:25: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
   fs/namei.c:197:25: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
   fs/namei.c:203:25: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
   fs/namei.c:208:25: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
   fs/namei.c:249:18: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
   fs/namei.c:249:18: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
   fs/namei.c:261:25: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
   fs/namei.c:267:17: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
   fs/namei.c:294:17: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
   fs/namei.c:297:17: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
   fs/namei.c: note: in included file (through include/linux/rbtree.h, include/linux/mm_types.h, include/linux/mmzone.h, ...):
   include/linux/rcupdate.h:871:25: sparse: sparse: context imbalance in 'leave_rcu' - unexpected unlock
   fs/namei.c:2518:19: sparse: sparse: context imbalance in 'path_init' - different lock contexts for basic block
--
   drivers/base/firmware_loader/main.c:229:9: sparse: sparse: context imbalance in 'free_fw_priv' - wrong count at exit
>> drivers/base/firmware_loader/main.c:509:16: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
>> drivers/base/firmware_loader/main.c:509:16: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)
   drivers/base/firmware_loader/main.c:591:9: sparse: sparse: cast truncates bits from constant value (123456789abcdef becomes 89abcdef)

vim +416 fs/d_path.c

7a5cf791a74764 Al Viro 2018-03-05  393  
7a5cf791a74764 Al Viro 2018-03-05  394  /*
7a5cf791a74764 Al Viro 2018-03-05  395   * NOTE! The user-level library version returns a
7a5cf791a74764 Al Viro 2018-03-05  396   * character pointer. The kernel system call just
7a5cf791a74764 Al Viro 2018-03-05  397   * returns the length of the buffer filled (which
7a5cf791a74764 Al Viro 2018-03-05  398   * includes the ending '\0' character), or a negative
7a5cf791a74764 Al Viro 2018-03-05  399   * error value. So libc would do something like
7a5cf791a74764 Al Viro 2018-03-05  400   *
7a5cf791a74764 Al Viro 2018-03-05  401   *	char *getcwd(char * buf, size_t size)
7a5cf791a74764 Al Viro 2018-03-05  402   *	{
7a5cf791a74764 Al Viro 2018-03-05  403   *		int retval;
7a5cf791a74764 Al Viro 2018-03-05  404   *
7a5cf791a74764 Al Viro 2018-03-05  405   *		retval = sys_getcwd(buf, size);
7a5cf791a74764 Al Viro 2018-03-05  406   *		if (retval >= 0)
7a5cf791a74764 Al Viro 2018-03-05  407   *			return buf;
7a5cf791a74764 Al Viro 2018-03-05  408   *		errno = -retval;
7a5cf791a74764 Al Viro 2018-03-05  409   *		return NULL;
7a5cf791a74764 Al Viro 2018-03-05  410   *	}
7a5cf791a74764 Al Viro 2018-03-05  411   */
7a5cf791a74764 Al Viro 2018-03-05  412  SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
7a5cf791a74764 Al Viro 2018-03-05  413  {
7a5cf791a74764 Al Viro 2018-03-05  414  	int error;
7a5cf791a74764 Al Viro 2018-03-05  415  	struct path pwd, root;
7a5cf791a74764 Al Viro 2018-03-05 @416  	char *page = __getname();

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