Operation steps & amp; problem phenomenon
1, sysbench prepare, 100 tables, each table 100 million, 50 concurrency.
Try attempts to lower the concurrent number to 25 or the data volume to 5kw. Eventually, there are various memory reporting errors in the create secondary index link.
parameter:
Physical Server memory: 128GB
gs_guc reload -N all -I all -c "shared_buffers='30GB'"
gs_guc reload -N all -I all -c "max_process_memory='90GB'"
gs_guc reload -N all -I all -c "maintenance_work_mem='10GB'"
Report wrong phenomenon 1:
249FATAL: `sysbench.cmdline.call_command' function failed: ./oltp_common.lua:245: db_bulk_insert_next() failed
FATAL: PQexec() failed: 7 memory is temporarily unavailable
FATAL: failed query was: CREATE INDEX k_56 ON sbtest56(k)
FATAL: `sysbench.cmdline.call_command' function failed: ./oltp_common.lua:253: SQL error, errno = 0, state = 'YY006': memory is temporarily unavailable
Creating table 'sbtest76'...
Inserting 100000000 records into
Report wrong phenomenon 2:
Message from syslogd#testserver at Feb 23 10:19:45 ...
systemd:Caught , cannot fork for core dump: Cannot allocate memory
Report wrong phenomenon 3：
opengauss hitch。
Creating a secondary index on 'sbtest9'...
Segmentation fault (core dumped)
log 3：
could not fork new process for connection: Cannot allocate memory
could not fork new process for connection: Cannot allocate memory
I'm on a VirtualBox with Ubuntu 18.10 installed on, and I'm new using it. My code creates 100 forked child that works on a shared memory. SOMETIME I get this message
Sender(Pid = (childPID)) terminated with status 0x008B.
Searching in the web I found that could be a SIGSEGV error. Is it true?
Finally, is there any way to find WHERE the code fails in over 1000 lines? I tryed using this Guide: http://www.unknownroad.com/rtfm/gdbtut/gdbsegfault.html to find the error with gdb but my terminal says me that I have "No Stack". I'm totally new with this kind of problems, any hint will be appreciated.
Sender(Pid = (childPID)) terminated with status 0x008B.
Searching in the web I found that could be a SIGSEGV error. Is it true?
Yes, that indicates termination by signal 11 (0xB).
Finally, is there any way to find WHERE the code fails in over 1000 lines?
I'd run the program with valgrind.
I have installed OpenMPI and tried to compile/execute one of the examples delivered with the newest version.
As I try to run with mpiexec it says that the address is already in use.
Someone got a hint why this is always happening?
Kristians-MacBook-Pro:examples kristian$ mpicc -o hello hello_c.c
Kristians-MacBook-Pro:examples kristian$ mpiexec -n 4 ./hello
[Kristians-MacBook-Pro.local:02747] [[56076,0],0] bind() failed on error Address already in use (48)
[Kristians-MacBook-Pro.local:02747] [[56076,0],0] ORTE_ERROR_LOG: Error in file oob_usock_component.c at line 228
[Kristians-MacBook-Pro.local:02748] [[56076,1],0] usock_peer_send_blocking: send() to socket 19 failed: Socket is not connected (57)
[Kristians-MacBook-Pro.local:02748] [[56076,1],0] ORTE_ERROR_LOG: Unreachable in file oob_usock_connection.c at line 315
[Kristians-MacBook-Pro.local:02748] [[56076,1],0] orte_usock_peer_try_connect: usock_peer_send_connect_ack to proc [[56076,0],0] failed: Unreachable (-12)
[Kristians-MacBook-Pro.local:02749] [[56076,1],1] usock_peer_send_blocking: send() to socket 20 failed: Socket is not connected (57)
[Kristians-MacBook-Pro.local:02749] [[56076,1],1] ORTE_ERROR_LOG: Unreachable in file oob_usock_connection.c at line 315
[Kristians-MacBook-Pro.local:02749] [[56076,1],1] orte_usock_peer_try_connect: usock_peer_send_connect_ack to proc [[56076,0],0] failed: Unreachable (-12)
-------------------------------------------------------
Primary job terminated normally, but 1 process returned
a non-zero exit code.. Per user-direction, the job has been aborted.
-------------------------------------------------------
--------------------------------------------------------------------------
mpiexec detected that one or more processes exited with non-zero status, thus causing
the job to be terminated. The first process to do so was:
Process name: [[56076,1],0]
Exit code: 1
--------------------------------------------------------------------------
Thanks in advance.
Okay.
I have now changed the $TMPDIR environment variable with export TMPDIR=/tmp and it works.
Now it seems to me that the OpenMPI Session folder was blocking my communication. But why did it?
Am I missing something here?
I wanted to start using gdbserver for remote debugging and so I tested-out its functionality on my local machine with a simple test program that generates a segfault shown below:
segfault.c -- compiles to elf named "test"
#define NULL ((void*)0)
int main()
{
int value = *((int*)NULL);
return value;
}
Now when I run:
#gdb test
(gdb)run
I get:
Starting program: /home/awaibel/digiworkspace/test/Debug/test
Program received signal SIGSEGV, Segmentation fault.
0x080483bf in main () at ../segfault.c:4
4 int value = *((int*)NULL);
however if I debug it with gdb server like so:
#gdbserver :65535 test
#gdb test
(gdb)target remote 127.0.0.1:65535
(gdb)continue
it gives me the debug info:
Program received signal SIGSEGV, Segmentation fault.
0x080483bf in ?? ()
it seems to give the same function address for the segfault, but the name and line number is omitted when debugging with the remote debugger. is it possible to have the remote debugger display this information, and if so, how?
I guess I should add that the program was compiled with GCC using the "-g" debug flag
Thanks to markys' comments I was able to figure out the problem. Since the gdb client is what parses the symbols and not the server, I had to make sure the client knew the full path to a copy of the executable. Since 'test' was not in the current directory for the command prompt that was used to run gdbtest it did not have a copy of the symbols to use. adding the the binary to PATH for the terminal running the client solved the problem. Thanks.
Summarizing:
server side:
gdbserver --multi :port "path-to-executable"
client side:
gdb "path-to-executable"
(gdb)> target remote "ip-of-the-remote-device:port"
I'm trying to attach a program with gdb but it returns:
Attaching to process 29139
Could not attach to process. If your uid matches the uid of the target
process, check the setting of /proc/sys/kernel/yama/ptrace_scope, or try
again as the root user. For more details, see /etc/sysctl.d/10-ptrace.conf
ptrace: Operation not permitted.
gdb-debugger returns "Failed to attach to process, please check privileges and try again."
strace returns "attach: ptrace(PTRACE_ATTACH, ...): Operation not permitted"
I changed "kernel.yama.ptrace_scope" 1 to 0 and /proc/sys/kernel/yama/ptrace_scope 1 to 0 and tried set environment LD_PRELOAD=./ptrace.so with this:
#include <stdio.h>
int ptrace(int i, int j, int k, int l) {
printf(" ptrace(%i, %i, %i, %i), returning -1\n", i, j, k, l);
return 0;
}
But it still returns the same error. How can I attach it to debuggers?
If you are using Docker, you will probably need these options:
docker run --cap-add=SYS_PTRACE --security-opt seccomp=unconfined
If you are using Podman, you will probably need its --cap-add option too:
podman run --cap-add=SYS_PTRACE
This is due to kernel hardening in Linux; you can disable this behavior by echo 0 > /proc/sys/kernel/yama/ptrace_scope or by modifying it in /etc/sysctl.d/10-ptrace.conf
See also this article about it in Fedora 22 (with links to the documentation) and this comment thread about Ubuntu and .
I would like to add that I needed --security-opt apparmor=unconfined along with the options that #wisbucky mentioned. This was on Ubuntu 18.04 (both Docker client and host). Therefore, the full invocation for enabling gdb debugging within a container is:
docker run --cap-add=SYS_PTRACE --security-opt seccomp=unconfined --security-opt apparmor=unconfined
Just want to emphasize a related answer. Let's say that you're root and you've done:
strace -p 700
and get:
strace: attach: ptrace(PTRACE_SEIZE, 700): Operation not permitted
Check:
grep TracerPid /proc/700/status
If you see something like TracerPid: 12, i.e. not 0, that's the PID of the program that is already using the ptrace system call. Both gdb and strace use it, and there can only be one active at a time.
Not really addressing the above use-case but I had this problem:
Problem: It happened that I started my program with sudo, so when launching gdb it was giving me ptrace: Operation not permitted.
Solution: sudo gdb ...
As most of us land here for Docker issues I'll add the Kubernetes answer as it might come in handy for someone...
You must add the SYS_PTRACE capability in your pod's security context
at spec.containers.securityContext:
securityContext:
capabilities:
add: [ "SYS_PTRACE" ]
There are 2 securityContext keys at 2 different places. If it tells you that the key is not recognized than you missplaced it. Try the other one.
You probably need to have a root user too as default. So in the other security context (spec.securityContext) add :
securityContext:
runAsUser: 0
runAsGroup: 0
fsGroup: 101
FYI : 0 is root. But the fsGroup value is unknown to me. For what I'm doing I don't care but you might.
Now you can do :
strace -s 100000 -e write=1 -e trace=write -p 16
You won't get the permission denied anymore !
BEWARE : This is the Pandora box. Having this in production it NOT recommended.
I was running my code with higher privileges to deal with Ethernet Raw Sockets by setting set capability command in Debian Distribution. I tried the above solution: echo 0 > /proc/sys/kernel/yama/ptrace_scope
or by modifying it in /etc/sysctl.d/10-ptrace.conf but that did not work for me.
Additionally, I also tried with set capabilities command for gdb in installed directory (usr/bin/gdb) and it works: /sbin/setcap CAP_SYS_PTRACE=+eip /usr/bin/gdb.
Be sure to run this command with root privileges.
Jesup's answer is correct; it is due to Linux kernel hardening. In my case, I am using Docker Community for Mac, and in order to do change the flag I must enter the LinuxKit shell using justin cormack's nsenter (ref: https://www.bretfisher.com/docker-for-mac-commands-for-getting-into-local-docker-vm/ ).
docker run -it --rm --privileged --pid=host justincormack/nsenter1
/ # cat /etc/issue
Welcome to LinuxKit
## .
## ## ## ==
## ## ## ## ## ===
/"""""""""""""""""\___/ ===
{ / ===-
\______ O __/
\ \ __/
\____\_______/
/ # cat /proc/sys/kernel/yama/ptrace_scope
1
/ # echo 0 > /proc/sys/kernel/yama/ptrace_scope
/ # exit
Maybe someone has attached this process with gdb.
ps -ef | grep gdb
can't gdb attach the same process twice.
I was going to answer this old question as it is unaccepted and any other answers are not got the point. The real answer may be already written in /etc/sysctl.d/10-ptrace.conf as it is my case under Ubuntu. This file says:
For applications launching crash handlers that need PTRACE, exceptions can
be registered by the debugee by declaring in the segfault handler
specifically which process will be using PTRACE on the debugee:
prctl(PR_SET_PTRACER, debugger_pid, 0, 0, 0);
So just do the same thing as above: keep /proc/sys/kernel/yama/ptrace_scope as 1 and add prctl(PR_SET_PTRACER, debugger_pid, 0, 0, 0); in the debugee. Then the debugee will allow debugger to debug it. This works without sudo and without reboot.
Usually, debugee also need to call waitpid to avoid exit after crash so debugger can find the pid of debugee.
If permissions are a problem, you probably will want to use gdbserver. (I almost always use gdbserver when I gdb, docker or no, for numerous reasons.) You will need gdbserver (Deb) or gdb-gdbserver (RH) installed in the docker image. Run the program in docker with
$ sudo gdbserver :34567 myprogram arguments
(pick a port number, 1025-65535). Then, in gdb on the host, say
(gdb) target remote 172.17.0.4:34567
where 172.17.0.4 is the IP address of the docker image as reported by /sbin/ip addr list run in the docker image. This will attach at a point before main runs. You can tb main and c to stop at main, or wherever you like. Run gdb under cgdb, emacs, vim, or even in some IDE, or plain. You can run gdb in your source or build tree, so it knows where everything is. (If it can't find your sources, use the dir command.) This is usually much better than running it in the docker image.
gdbserver relies on ptrace, so you will also need to do the other things suggested above. --privileged --pid=host sufficed for me.
If you deploy to other OSes or embedded targets, you can run gdbserver or a gdb stub there, and run gdb the same way, connecting across a real network or even via a serial port (/dev/ttyS0).
I don't know what you are doing with LD_PRELOAD or your ptrace function.
Why don't you try attaching gdb to a very simple program? Make a program that simply repeatedly prints Hello or something and use gdb --pid [hello program PID] to attach to it.
If that does not work then you really do have a problem.
Another issue is the user ID. Is the program that you are tracing setting itself to another UID? If it is then you cannot ptrace it unless you are using the same user ID or are root.
I have faced the same problem and try a lot of solution but finally, I have found the solution, but really I don't know what the problem was. First I modified the ptrace_conf value and login into Ubuntu as a root but the problem still appears. But the most strange thing that happened is the gdb showed me a message that says:
Could not attach to process. If your uid matches the uid of the target process, check the setting of /proc/sys/kernel/yama/ptrace_scope, or try again as the root user.
For more details, see /etc/sysctl.d/10-ptrace.conf
warning: process 3767 is already traced by process 3755 ptrace: Operation not permitted.
With ps command terminal, the process 3755 was not listed.
I found the process 3755 in /proc/$pid but I don't understand what was it!!
Finally, I deleted the target file (foo.c) that I try to attach it vid gdb and tracer c program using PTRACE_ATTACH syscall, and in the other folder, I created another c program and compiled it.
the problem is solved and I was enabled to attach to another process either by gdb or ptrace_attach syscall.
(gdb) attach 4416
Attaching to process 4416
and I send a lot of signals to process 4416. I tested it with both gdb and ptrace, both of them run correctly.
really I don't know the problem what was, but I think it is not a bug in Ubuntu as a lot of sites have referred to it, such https://askubuntu.com/questions/143561/why-wont-strace-gdb-attach-to-a-process-even-though-im-root
Extra information
If you wanna make changes in the interfaces such as add the ovs bridge, you must use --privileged instead of --cap-add NET_ADMIN.
sudo docker run -itd --name=testliz --privileged --cap-add=SYS_PTRACE --security-opt seccomp=unconfined ubuntu
If you are using FreeBSD, edit /etc/sysctl.conf, change the line
security.bsd.unprivileged_proc_debug=0
to
security.bsd.unprivileged_proc_debug=1
Then reboot.