| Date | Thu, 5 May 2022 17:01:59 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH v3 08/11] ptrace: Admit ptrace_stop can generate spuriuos SIGTRAPs |
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On 05/04, Eric W. Biederman wrote: > > With the removal of the incomplete detection of the tracer going away > in ptrace_stop, ptrace_stop always sleeps in schedule after > ptrace_freeze_traced succeeds. Modify ptrace_check_attach to > warn if wait_task_inactive fails.
Oh. Again, I don't understand the changelog. If we forget about RT, ptrace_stop() will always sleep if ptrace_freeze_traced() succeeds. may_ptrace_stop() has gone.
IOW. Lets forget about RT
> --- a/kernel/ptrace.c > +++ b/kernel/ptrace.c > @@ -266,17 +266,9 @@ static int ptrace_check_attach(struct task_struct *child, bool ignore_state) > } > read_unlock(&tasklist_lock); > > - if (!ret && !ignore_state) { > - if (!wait_task_inactive(child, __TASK_TRACED)) { > - /* > - * This can only happen if may_ptrace_stop() fails and > - * ptrace_stop() changes ->state back to TASK_RUNNING, > - * so we should not worry about leaking __TASK_TRACED. > - */ > - WARN_ON(READ_ONCE(child->__state) == __TASK_TRACED); > - ret = -ESRCH; > - } > - } > + if (!ret && !ignore_state && > + WARN_ON_ONCE(!wait_task_inactive(child, __TASK_TRACED))) > + ret = -ESRCH; > > return ret; > }
Why do you think this change would be wrong without any other changes?
Oleg.
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