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-h... base: https://git.kernel.org/pub/scm/linux/kernel/git/rw/uml.git linux-next config: nds32-defconfig (attached as .config) compiler: nds32le-linux-gcc (GCC) 9.2.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # save the attached .config to linux build tree GCC_VERSION=9.2.0 make.cross ARCH=nds32 If you fix the issue, kindly add following tag Reported-by: kbuild test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): fs/proc/base.c: In function 'proc_flush_task': 3217 | proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr, | ^~ 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(a)openvz.org&gt; :::::: CC: Linus Torvalds <torvalds(a)woody.linux-foundation.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org