Re: [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped.

From: Robert O'Callahan
Date: Sun Sep 03 2017 - 23:19:24 EST


Sorry about replying to this old thread, but...

On Mon, Apr 3, 2017 at 9:07 AM, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
> I don't know who actually useses PTRACE_O_TRACEEXIT so I don't actually
> know what the implications of changing it are. Let's see...
>
> gdb - no
> upstart - no
> lldb - yes
> strace - no

For the record, rr uses PTRACE_O_TRACEEXIT.

When a thread exits we need to examine its address space to find its
robust futex list and record the changes that will be performed by the
kernel as it cleans up that list. So, any failures to deliver
PTRACE_EVENT_EXIT are potentially problematic for us because we won't
get a chance to examine the address space before it disappears.

Rob
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