Re: [RFC][PATCH] cgroup: Don't mess with tasks in exec

[Tejun Heo]

Hello,

On Thu, May 10, 2018 at 02:15:32PM +0200, Oleg Nesterov wrote:
> > So avoid the problems by simply blocking cgroup migration over the
> > entirety of exec.
> 
> This patch, even if it was correct, will bring much more problems.
> 
> If nothing else exec() is very slow. If it races with migration which needs
> this sem for writing the new readers will be blocked. This means that clone(),
> exit(), or another exec() will block too.

Agreed.  I don't think it's a good idea to expand threadgroup coverage
larger than it already is.  I'd much prefer either working around the
copy_string case specifically or just ignoring it.

Thanks.

-- 
tejun