On 05/04, Eric W. Biederman wrote: > > Oleg Nesterov <o...@redhat.com> writes: > > > OK, what about exec() ? mm_init_memcg() initializes bprm->mm->memcg early in > > bprm_mm_init(). What if the execing task migrates before exec_mmap() ? > > We need the the cgroup when the mm is initialized. That way we have the > cgroup information when initializing the mm.
Yes, we need to initialize new_mm->memcg but iiuc mostly for the error path, > I don't know if a lock preventing changing the cgroup in exec or just > a little bit of code in exec_mmap to ensure mm->memcg is properly set > is the better approach. I'd vote for the change in exec_mmap(). This way mm_init_memcg() can just nullify mm->memcg. > This does look like a very good place for an incremental patch to close > that race. Hmm. I think v2 makes more sense, but I won't argue. Oleg.