Re: [PATCH net] net: memcontrol: charge allocated memory after mem_cgroup_sk_alloc()

[Roman Gushchin]

On Thu, Feb 01, 2018 at 10:16:55AM -0500, David Miller wrote:
> From: Roman Gushchin <guro@xxxxxx>
> Date: Wed, 31 Jan 2018 21:54:08 +0000
> 
> > So I really start thinking that reverting 9f1c2674b328
> > ("net: memcontrol: defer call to mem_cgroup_sk_alloc()")
> > and fixing the original issue differently might be easier
> > and a proper way to go. Does it makes sense?
> 
> You'll need to work that out with Eric Dumazet who added the
> change in question which you think we should revert.

Eric,

can you, please, provide some details about the use-after-free problem
that you've fixed with commit 9f1c2674b328 ("net: memcontrol: defer call
to mem_cgroup_sk_alloc()" ? Do you know how to reproduce it?

Deferring mem_cgroup_sk_alloc() breaks socket memory accounting
and makes it much more fragile in general. So, I wonder, if there are
solutions for the use-after-free problem.

Thank you!

Roman