Re: [PATCH v3] proc: Fix a dentry lock race between release_task and lookup

Re: [PATCH v3] proc: Fix a dentry lock race between release_task and lookup

[kernel test robot]

Hi Zhihao,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v5.18 next-20220601]
[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]

url:    https://github.com/intel-lab-lkp/linux/commits/Zhihao-Cheng/proc-Fix-a-dentry-lock-race-between-release_task-and-lookup/20220601-102513
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 700170bf6b4d773e328fa54ebb70ba444007c702
config: x86_64-randconfig-a005 (https://download.01.org/0day-ci/archive/20220601/202206011314.dh4oSNjS-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project c825abd6b0198fb088d9752f556a70705bc99dfd)
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://github.com/intel-lab-lkp/linux/commit/9dfec748ded82f145043dc08a944e1a9af7a640d
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Zhihao-Cheng/proc-Fix-a-dentry-lock-race-between-release_task-and-lookup/20220601-102513
        git checkout 9dfec748ded82f145043dc08a944e1a9af7a640d
        # 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=x86_64 SHELL=/bin/bash fs/proc/

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/proc/base.c:1929:15: warning: no previous prototype for function 'proc_pid_make_base_inode' [-Wmissing-prototypes]
   struct inode *proc_pid_make_base_inode(struct super_block *sb,
                 ^
   fs/proc/base.c:1929:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   struct inode *proc_pid_make_base_inode(struct super_block *sb,
   ^
   static 
   1 warning generated.


vim +/proc_pid_make_base_inode +1929 fs/proc/base.c

  1928	
> 1929	struct inode *proc_pid_make_base_inode(struct super_block *sb,
  1930					       struct task_struct *task, umode_t mode)
  1931	{
  1932		struct inode *inode;
  1933		struct proc_inode *ei;
  1934		struct pid *pid;
  1935	
  1936		inode = proc_pid_make_inode(sb, task, mode);
  1937		if (!inode)
  1938			return NULL;
  1939	
  1940		/* Let proc_flush_pid find this directory inode */
  1941		ei = PROC_I(inode);
  1942		pid = ei->pid;
  1943		spin_lock(&pid->lock);
  1944		hlist_add_head_rcu(&ei->sibling_inodes, &pid->inodes);
  1945		spin_unlock(&pid->lock);
  1946	
  1947		return inode;
  1948	}
  1949	

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