On Thu, May 21, 2015 at 11:47 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
> On Thu, May 21, 2015 at 3:30 AM, Alban Crequy <alban.crequy@xxxxxxxxx> wrote:
>> From: Alban Crequy <alban@xxxxxxxxxxxx>
>>
>> commit 818411616baf ("fs, proc: introduce
>> /proc/<pid>/task/<tid>/children entry") introduced the children entry
>> for checkpoint restore and the file is only available on kernels
>> configured with CONFIG_EXPERT and CONFIG_CHECKPOINT_RESTORE.
>>
>> This is available in most distributions (Fedora, Debian, Ubuntu, CoreOS)
>> because they usually enable CONFIG_EXPERT and CONFIG_CHECKPOINT_RESTORE.
>> But Arch does not enable CONFIG_EXPERT or CONFIG_CHECKPOINT_RESTORE.
>>
>> However, the children proc file is useful outside of checkpoint restore.
>> I would like to use it in rkt. The rkt process exec() another program it
>> does not control, and that other program will fork()+exec() a child
>> process. I would like to find the pid of the child process from an
>> external tool without iterating in /proc over all processes to find
>> which one has a parent pid equal to rkt.
>>
>> Since the children proc file is useful outside of checkpoint-restore,
>> I am removing the guard on CONFIG_CHECKPOINT_RESTORE.
>
> I sent an essentially identical patch a couple years ago, and it got
> some interesting comments:
>
> http://lkml.kernel.org/g/0e00e9073855c02a382d49ba1ede9c4fda3451b7.1372189875.git.luto@xxxxxxxxxxxxxx
Thanks for the pointer, I didn't see it.
> See also:
>
> http://lkml.kernel.org/g/5f9a6b3ab75b12f2c5ba61ea1f6f3b08e9952b55.1372280661.git.luto@xxxxxxxxxxxxxx
Your paragraph seems good to have in the documentation but I am also
not qualified to comment on the behavior.
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