Re: [PATCH 3/3] proc: Remove the now unnecessary internal mount of proc

[kbuild test robot]

Hi "Eric,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on uml/linux-next]
[also build test ERROR on linux/master kees/for-next/pstore linus/master v5.6-rc3 next-20200228]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Eric-W-Biederman/proc-Actually-honor-the-mount-options/20200229-100926
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rw/uml.git linux-next
config: x86_64-defconfig (attached as .config)
compiler: gcc-7 (Debian 7.5.0-5) 7.5.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@xxxxxxxxx>

All errors (new ones prefixed by >>):

   fs/proc/base.c: In function 'proc_flush_task':
>> fs/proc/base.c:3217:33: error: 'struct pid_namespace' has no member named 'proc_mnt'; did you mean 'proc_self'?
      proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr,
                                    ^~~~~~~~
                                    proc_self

vim +3217 fs/proc/base.c

^1da177e4c3f41 Linus Torvalds    2005-04-16  3180  
0895e91d60ef9b Randy Dunlap      2007-10-21  3181  /**
0895e91d60ef9b Randy Dunlap      2007-10-21  3182   * proc_flush_task -  Remove dcache entries for @task from the /proc dcache.
0895e91d60ef9b Randy Dunlap      2007-10-21  3183   * @task: task that should be flushed.
0895e91d60ef9b Randy Dunlap      2007-10-21  3184   *
0895e91d60ef9b Randy Dunlap      2007-10-21  3185   * When flushing dentries from proc, one needs to flush them from global
60347f6716aa49 Pavel Emelyanov   2007-10-18  3186   * proc (proc_mnt) and from all the namespaces' procs this task was seen
0895e91d60ef9b Randy Dunlap      2007-10-21  3187   * in. This call is supposed to do all of this job.
0895e91d60ef9b Randy Dunlap      2007-10-21  3188   *
0895e91d60ef9b Randy Dunlap      2007-10-21  3189   * Looks in the dcache for
0895e91d60ef9b Randy Dunlap      2007-10-21  3190   * /proc/@pid
0895e91d60ef9b Randy Dunlap      2007-10-21  3191   * /proc/@tgid/task/@pid
0895e91d60ef9b Randy Dunlap      2007-10-21  3192   * if either directory is present flushes it and all of it'ts children
0895e91d60ef9b Randy Dunlap      2007-10-21  3193   * from the dcache.
0895e91d60ef9b Randy Dunlap      2007-10-21  3194   *
0895e91d60ef9b Randy Dunlap      2007-10-21  3195   * It is safe and reasonable to cache /proc entries for a task until
0895e91d60ef9b Randy Dunlap      2007-10-21  3196   * that task exits.  After that they just clog up the dcache with
0895e91d60ef9b Randy Dunlap      2007-10-21  3197   * useless entries, possibly causing useful dcache entries to be
0895e91d60ef9b Randy Dunlap      2007-10-21  3198   * flushed instead.  This routine is proved to flush those useless
0895e91d60ef9b Randy Dunlap      2007-10-21  3199   * dcache entries at process exit time.
0895e91d60ef9b Randy Dunlap      2007-10-21  3200   *
0895e91d60ef9b Randy Dunlap      2007-10-21  3201   * NOTE: This routine is just an optimization so it does not guarantee
0895e91d60ef9b Randy Dunlap      2007-10-21  3202   *       that no dcache entries will exist at process exit time it
0895e91d60ef9b Randy Dunlap      2007-10-21  3203   *       just makes it very unlikely that any will persist.
60347f6716aa49 Pavel Emelyanov   2007-10-18  3204   */
60347f6716aa49 Pavel Emelyanov   2007-10-18  3205  
60347f6716aa49 Pavel Emelyanov   2007-10-18  3206  void proc_flush_task(struct task_struct *task)
60347f6716aa49 Pavel Emelyanov   2007-10-18  3207  {
9fcc2d15b14894 Eric W. Biederman 2007-11-14  3208  	int i;
9b4d1cbef8f41a Oleg Nesterov     2009-09-22  3209  	struct pid *pid, *tgid;
130f77ecb2e7d5 Pavel Emelyanov   2007-10-18  3210  	struct upid *upid;
130f77ecb2e7d5 Pavel Emelyanov   2007-10-18  3211  
130f77ecb2e7d5 Pavel Emelyanov   2007-10-18  3212  	pid = task_pid(task);
130f77ecb2e7d5 Pavel Emelyanov   2007-10-18  3213  	tgid = task_tgid(task);
9fcc2d15b14894 Eric W. Biederman 2007-11-14  3214  
9fcc2d15b14894 Eric W. Biederman 2007-11-14  3215  	for (i = 0; i <= pid->level; i++) {
130f77ecb2e7d5 Pavel Emelyanov   2007-10-18  3216  		upid = &pid->numbers[i];
130f77ecb2e7d5 Pavel Emelyanov   2007-10-18 @3217  		proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr,
9b4d1cbef8f41a Oleg Nesterov     2009-09-22  3218  					tgid->numbers[i].nr);
130f77ecb2e7d5 Pavel Emelyanov   2007-10-18  3219  	}
60347f6716aa49 Pavel Emelyanov   2007-10-18  3220  }
60347f6716aa49 Pavel Emelyanov   2007-10-18  3221  

:::::: The code at line 3217 was first introduced by commit
:::::: 130f77ecb2e7d5ac3e53e620f55e374f4a406b20 pid namespaces: make proc_flush_task() actually from entries from multiple namespaces

:::::: TO: Pavel Emelyanov <xemul@xxxxxxxxxx>
:::::: CC: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxxxxxxxx>

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