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Date: Fri, 28 Feb 2020 22:49:15 -0600
From: ebiederm@...ssion.com (Eric W. Biederman)
To: kbuild test robot <lkp@...el.com>
Cc: kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] proc: Remove the now unnecessary internal mount of proc
kbuild test robot <lkp@...el.com> writes:
> Hi "Eric,
>
> Thank you for the patch! Yet something to improve:
Dear kbuild robot,
Yep. You got it the wrong base. I will see about using --base
if I repost, or have another patchset that so clearly needs
to be applied on top of a non-default base.
Thank you for writing me how to do that.
Eric
> [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@...el.com>
>
> 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/@...d/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@...nvz.org>
> :::::: CC: Linus Torvalds <torvalds@...dy.linux-foundation.org>
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
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