Chen Jingpiao's GSoC status report - #1 of #13

[Zhibin Li]

Hi,

JFYI, I've also tried your reproducer on my laptop using a newly installed
ubuntu 18.04.

$ uname -r
4.17.0-rc5+
$ ldd --version
ldd (Ubuntu GLIBC 2.27-3ubuntu1) 2.27
...
$ ./strace -eclone ./a.out
clone(child_stack=NULL,
flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD,
child_tidptr=0x7fccc3684790) = 3723
3723
+++ exited with 0 +++
$ dmesg
[49004.917782] traps: a.out[3723] general protection ip:7fccc3165dfe
sp:7fff6d775c58 error:0 in libc-2.27.so[7fccc3081000+1e7000]

I'm curious while getting this error log, I still can't reproduce the
problem you said so I wonder if this error is really the cause of your
problem.
I can't figure it out and I guess I should learn more about this "general
protection".

Zhibin Li

On Mon, May 21, 2018 at 11:54 PM, Chen Jingpiao <chenjingpiao at gmail.com>
wrote:

> Unfortunately, the progress was slow last week. I meet a fault that I
> never meet.
> It took me a lot of time to debug.
>
> I report the bug here, look forward to someone can give me a help.
>
> Environment:
> $ uname -a
> Linux VM-250-130-ubuntu 4.16.0-rc5 #14 SMP Tue Mar 20 11:06:37 CST 2018
> x86_64 x86_64 x86_64 GNU/Linux
>
> glibc: libc-2.19.so
>
> Description:
> The child process does not return after fork().
>
> $ dmesg
> [ 4648.471410] traps: a.out[31678] general protection
> ip:7fed4d16e100 sp:7fff286159e8 error:0 in libc-2.19.so[7fed4d0a9000+
> 1be000]
>
> Reproduce the fault:
> $ git remote add ppiao https://github.com/ppiao/strace.git
> $ git fetch ppiao ppiao/next:ppiao/next
> $ git checkout ppiao/next
> $ ./bootstrap && ./configure && make
> $ ./strace -eopen ls >/dev/null # work properly
>
> /* fork.c */
> #include <stdio.h>
> #include <unistd.h>
>
> int main(void)
> {
> int pid = fork();
>
> fprintf(stderr, "%d\n", pid);
>
> return 0;
> }
>
> $ gcc fork.c
> $ ./strace -eclone ./a.out # the child process does not return
> $ dmesg
> [ 4648.471410] traps: a.out[31678] general protection
> ip:7fed4d16e100 sp:7fff286159e8 error:0 in libc-2.19.so[7fed4d0a9000+
> 1be000]
>
> Thank you!
>
> --
> Chen Jingpiao
>
> --
> Strace-devel mailing list
> Strace-devel at lists.strace.io
> https://lists.strace.io/mailman/listinfo/strace-devel
>
>
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