[CRIU] Dumping a restored apache process

[Deyan Doychev]

Hi again,

Now I am having issues trying to dump a previously restored httpd
(apache) process but I am hitting this:

(00.079994) fdinfo: type: 0x 4 flags: 02/01 pos: 0x       0 fd: 3
(00.080018) 6560 fdinfo 4: pos: 0x               0 flags:               
2/0x1
(00.080027)     Searching for socket 122b71d (family 10)
(00.080032) Error (sk-inet.c:250): BUG at sk-inet.c:250
pie: Error (pie/parasite.c:371): Trimmed message received (12/0)
pie: 6560: new_sp=0x7fa51eb63008 ip 0x7f92f78bee59
Aborted

Here is the whole use-case:
1. start httpd
    Let's say main httpd process pid is 9499

2. criu dump --tcp-established --file-locks -t 9499
    It successfully dumps.

3. criu restore --tcp-established --file-locks --restore-detached
    It successfully restores.

4. criu dump --tcp-established --file-locks -t 9499 -v4
    Here I get the error described above.

5. If I decide to dump it again I get:

(00.000881) Writing image inventory (version 1)
(00.000961) Collected 1.pid namespace
(00.000972) Collected 2.net namespace
(00.000982) Collected 3.ipc namespace
(00.000991) Collected 4.uts namespace
(00.000998) Collected 5.mnt namespace
(00.003146) Error (ptrace.c:122): SEIZE 9499: task not stopped after seize
(00.003161) Unfreezing tasks into 1
(00.003165)     Unseizing 9499 into 1
(00.003172) Unlock network
(00.003180) Unfreezing tasks into 1
(00.003189)     Unseizing 9499 into 1
(00.003233) Error (cr-dump.c:1854): Dumping FAILED.

After this error I got no dump and the httpd process is stopped.

I see we check if the socket is already dumped and if so we BUG. However
sometimes (rarely) I am able to dump and restore the process again and
if so I get the BUG on the third attampt to dump it. I've never
succeeded going further than one dump of a previously-restored process.

Is this intentional and how can I be sure If after the attempt to dump
the restored httpd process I won't get to the point where the next dump
is "fatal" for this process?

Thanks,
Deyan

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