[CRIU] [PATCH] s390: Prevent GOT relocations

[Michael Holzheu]

Am Mon, 17 Jul 2017 10:07:23 +0200
schrieb Adrian Reber <areber at redhat.com>:

> On Fri, Jul 14, 2017 at 02:56:26PM +0200, Michael Holzheu wrote:
> > Am Fri, 14 Jul 2017 14:08:31 +0200
> > schrieb Adrian Reber <areber at redhat.com>:
> > 
> > > Thanks for the patch. I tried it on my s390 test system and I get the
> > > following error now:
> > 
> > Ok, fine - at least we don't see the compiler error any more.
> > 
> > > 
> > > (00.002625)        f15 0000000000000000
> > > (00.002626)        No VXRS
> > > (00.002628) Putting tsock into pid 24
> > > (00.002639) ptrace_set_regs: pid=24
> > > (00.002656) Error (compel/src/lib/infect.c:633): Unable to connect a transport socket: Function not implemented
> > > (00.002665) Error (compel/src/lib/infect.c:559): Can't inject syscall blob (pid: 24)
> > > (00.002667) Error (compel/src/lib/infect.c:1312): munmap for remote map 0x3fffd5c5000, 53248 returned 4398002229248
> > > (00.002669) Error (criu/cr-dump.c:1362): Can't infect (pid: 24) with parasite
> > > (00.002720) Unlock network
> > > (00.002735) Unfreezing tasks into 1
> > > (00.002737) 	Unseizing 24 into 1
> > > (00.002740) Error (compel/src/lib/infect.c:341): Unable to detach from 24: No such process
> > > (00.002745) 	Unseizing 25 into 1
> > > (00.002754) Error (criu/cr-dump.c:1800): Dumping FAILED.
> > 
> > I think the problem is not related to the patch.
> > Could you send me the full log?
> 
> https://lisas.de/~adrian/dump-log.s390

I assume that the target process "somehow" dies very early when
the parasite code is started:

compel/src/lib/infect.c:

 627         if (parasite_run(pid, PTRACE_CONT, ctl->parasite_ip, ctl->rstack, &regs, &ctl->orig))
 628                 goto err;

Here the __export_parasite_head_start() function is executed in the target
process. This function then calls the parasite_service() function with
the PARASITE_CMD_INIT_DAEMON command:

compel/arch/s390/plugins/std/parasite-head.S:

ENTRY(__export_parasite_head_start)
        larl    %r14,__export_parasite_cmd
        llgf    %r2,0(%r14)
        larl    %r3,__export_parasite_args
        brasl   %r14,parasite_service
        .long 0x00010001        /* S390_BREAKPOINT_U16: Generates SIGTRAP */
__export_parasite_cmd:
        .long 0

Perhaps you could manually try the following:

 1) Run sleep program:

    # ulimit -c unlimited
    # sleep 10000
      [1] 8532

 2) Checkpoint program

    # mkdir ~/dump
    # criu/criu dump -t 8532 --shell-job -D ~/dump

 3) Check if we got a core dump for the sleep process

Unfortunately I currently can't reproduce this on my RHEL7.4 kernel 3.10.0-685.el7.s390x
because of a different problem:

 ~/criu # criu/criu dump -t 14545 --shell-job -D ~/dump/
 Error (criu/proc_parse.c:2654): Can't open 14545/task/14545/children on procfs: No such file or directory
 Error (criu/cr-dump.c:1800): Dumping FAILED.

 ~/criu # ls /proc/14545/task/14545/children
 ls: cannot access /proc/14545/task/14545/children: No such file or directory

I assmue the problem is that my kernel has not enabled CONFIG_CHECKPOINT_RESTORE.

Michael



Michael