* Andrei Vagin: > On Tue, Aug 30, 2022 at 6:18 PM Andrei Vagin <avagin@xxxxxxxxx> wrote: >>On Tue, Aug 30, 2022 at 10:49:43PM +0300, Alexey Izbyshev wrote: > <snip> >>> @@ -1030,6 +1033,10 @@ static int exec_mmap(struct mm_struct *mm) >>> tsk->mm->vmacache_seqnum = 0; >>> vmacache_flush(tsk); >>> task_unlock(tsk); >>> + >>> + if (vfork) >>> + timens_on_fork(tsk->nsproxy, tsk); >>> + >>> >>> Similarly, even after a normal vfork(), time namespace switch could be >>> silently skipped if the parent dies before "tsk->vfork_done" is read. Again, >>> I don't know whether anybody cares, but this behavior seems non-obvious and >>> probably unintended to me. >> This is the more interesting case. I will try to find out how we can >> handle it properly. > > It might not be a good idea to use vfork_done in this case. Let's > think about what we have and what we want to change. We don't want to > allow switching timens if a process mm is used by someone else. But we > forgot to handle execve that creates a new mm, and we can't change this > behavior right now because it can affect current users. Right? > > So maybe the best choice, in this case, is to change behavior by adding > a new control that enables it. The first interface that comes to my mind > is to introduce a new ioctl for a namespace file descriptor. Here is a > draft patch below that should help to understand what I mean. Doesn't this bring back the old posix_spawn (vfork) failure? Thanks, Florian
