2012/10/24 Andrew Morton <[email protected]>: > On Wed, 24 Oct 2012 09:38:57 +0400 > Andrey Wagin <[email protected]> wrote: > >> > >> > I think that returning -ENOMEM in response to an excessive nesting >> > attempt is misleading - the system *didn't* run out of memory. EINVAL >> > is better? >> >> I chose ENOMEM by analogy with max_pid. When a new PID can not be >> allocated, ENOMEM is returned too. > > I don't know what this means - please be carefully specific when > identifying kernel code.
Sorry.
>
> If you're referring to kernel/pid.c:alloc_pid() then -ENOMEM is
> appropriate there, because a failure *is* caused by memory allocation
> failure.
I'm referring to alloc_pidmap().
For example I set pid_max to 500 and try to create more than 500 processes.
[pid 345] clone(child_stack=0,
flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD,
child_tidptr=0x7f8721716a10) = -1 ENOMEM (Cannot allocate memory)
Actually I'm agree with EINVAL and a patch is attached to this message.
Thanks.
>
> But ENOMEM isn't appropriate for nesting-depth-exceeded - we shouldn't
> tell the user "you ran out of memory" when he didn't! -EINVAL isn't
> really appropriate either ("Invalid argument") but it has become a
> general you-screwed-up catchall and seems to me to be the most
> appropriate errno we have available.
>
0001-pidns-limit-the-nesting-depth-of-pid-namespaces-v2.patch
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