warning: Can‘t attach LWP 540028960: No child processes

最近使用GDB调试自己的程序，遇到一个问题：

warning: Can't attach LWP 540028960: No child processes
linux-thread-db.c:434: internal-error: thread_get_info_callback: Assertion `inout->thread_info != NULL' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) n

linux-thread-db.c:434: internal-error: thread_get_info_callback: Assertion `inout->thread_info != NULL' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Create a core file of GDB? (y or n) y

一番查找之后，这个问题基本确定是GDB的bug，但是对应自己的应用程序可能也存在一些问题。可以参考：

https://sourceware.org/bugzilla/show_bug.cgi?id=18006

Bug ID: 18006
Summary: internal error if threaded program calls
clone(CLONE_VM)
Product: gdb
Version: HEAD
Status: NEW
Severity: normal
Priority: P2
Component: threads
Assignee: unassigned at sourceware dot org
Reporter: palves at redhat dot com

On GNU/Linux, if a pthreaded program has a thread call clone(CLONE_VM)
directly,
and then that clone LWP hits a debug event (breakpoint, etc.) GDB internal
errors. Threaded programs shouldn't really be calling clone directly, but GDB
shouldn't crash either.

On GDB 7.9, the crash looks like:

(gdb) break clone_fn
Breakpoint 2 at 0x4007d8: file clone-thread_db.c, line 35.
(gdb) r
...
[Thread debugging using libthread_db enabled]
...
/home/pedro/gdb/mygit/src/gdb/linux-nat.c:1030: internal-error:
lin_lwp_attach_lwp: Assertion `lwpid > 0' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.

On earlier releases, it looked like this:

(gdb) b clone_fn
Breakpoint 1 at 0x4007d8: file clone-thread_db.c, line 35.
(gdb) r
...
[Thread debugging using libthread_db enabled]
...
[New Thread 0x7ffff7fc2700 (LWP 3886)]
../../gdb/linux-thread-db.c:437: internal-error: thread_get_info_callback:
Assertion `inout->thread_info != NULL' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.

1、https://stackoverflow.com/questions/20726907/gdb-internal-error-when-using-clone

2、https://sourceware.org/bugzilla/show_bug.cgi?id=18006

3、https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=730444

4、https://gdb-prs.sourceware.narkive.com/fHUhcwS4/bug-threads-18006-new-internal-error-if-threaded-program-calls-clone-clone-vm

有遇到同样问题的，有更清楚的说明的，欢迎留言。