To my knowledge, UML on 64-bit is a no-go at this point. I also happen
to know that it is an issue that is being worked on. You MAY be able to
get it working by emptying the /lib/tls directory on the guest, but that
is baseless rumor and no guarantees. I would seriously recommend that
you go with 32 bit at this point if you are planning on using this
machine for anything approaching a production environment. Try again in
6 months. Sorry...
Jonas
jez wrote:
> Hi Guys,
>
> We're trying to run a pure 64-bit environment (the debian etch
> amd64 port on both host and guests) but we're having serious
> problems running our server applications on the guests. To my
> untrained eyes, it looks like a process calls clone() and then
> it's child and itself get killed off by a SIGSEGV. I've included
> some straces down below. Any insight or direction anyone can offer
> would be much appreciated. A solution that doesn't involve changing
> the host kernel wins full points! :-)
>
> We tested this stuff using host:
>
> * debian stock 2.6.18-3-amd64 kernel
>
> and guests:
>
> * 2.6.20 from kernel.org
> * 2.6.18 with debian patches applied
>
> Most of the testing was done using the default configuration
> (ARCH=um make defconfig) but statically linked. We tried a few
> other configurations as well but the problem remained.
>
> We usually run UML instances inside chroot jails, but we've
> also tested all this stuff in the wild with:
>
> ./vmlinux umid=tuff mem=160M ubda=fs.cow,fs.base \
> ubdb=swapfile eth0=tuntap,ituff con=pts ssl=pts uml_dir=tmp
>
> Startup output looks like:
> Checking that ptrace can change system call numbers...OK
> Checking syscall emulation patch for ptrace...missing
> Checking for tmpfs mount on /dev/shm...OK
> Checking PROT_EXEC mmap in /dev/shm/...OK
> Checking for the skas3 patch in the host:
> - /proc/mm...not found
> - PTRACE_FAULTINFO...not found
> - PTRACE_LDT...not found
> UML running in SKAS0 mode
> Checking that ptrace can change system call numbers...OK
> Checking syscall emulation patch for ptrace...missing
>
> The server software that we've been testing with (Asterisk and
> Apache) are standard debian packages that seem to work fine
> on the host platform. We also compiled Asterisk from it's
> original source on a guest and tried that as well. All this
> stuff (configurations, packages, etc) work fine for us on x86.
>
> I'm including three sample strace outputs:
>
> (1) A trace taken from the host when sshd is the only server
> running on the guest.
> (2) A guest trace of Asterisk dying.
> (3) A guest trace of Apache running. Unlike Asterisk, Apache
> doesn't get killed. I reckon this is because it
> registers a signal handler, but what do I know. :-)
>
> I've got plenty more traces but the other ones tend to be
> very verbose.
>
> (1) Sample trace of the guest doing nothing much:
> ...
> --- SIGALRM (Alarm clock) @ 0 (0) ---
> setitimer(ITIMER_REAL, {it_interval={0, 0}, it_value={0, 0}}, NULL) = 0
> setitimer(ITIMER_VIRTUAL, {it_interval={0, 10000}, it_value={0, 10000}},
> NULL) = 0
> rt_sigprocmask(SIG_UNBLOCK, [USR1], [USR1 ALRM WINCH IO], 8) = 0
> setitimer(ITIMER_VIRTUAL, {it_interval={0, 0}, it_value={0, 0}}, NULL) = 0
> setitimer(ITIMER_REAL, {it_interval={0, 10000}, it_value={0, 10000}}, NULL) = > 0
> rt_sigreturn(0) = -1 EINTR (Interrupted system call)
> nanosleep({10, 0}, 0) = ? ERESTART_RESTARTBLOCK (To be restarted)
> --- SIGALRM (Alarm clock) @ 0 (0) ---
> ...
> --- SIGCHLD (Child exited) @ 0 (0) ---
> wait4(5627, [{WIFSTOPPED(s) && WSTOPSIG(s) == 133}], WSTOPPED, NULL) = 5627
> ptrace(PTRACE_GETREGS, 5627, 0, 0x60e9f188) = 0
> ptrace(PTRACE_GETFPREGS, 5627, 0, 0x60e9f260) = 0
> ptrace(PTRACE_POKEUSER, 5627, 8*ORIG_RAX, 0x27) = 0
> ptrace(PTRACE_SYSCALL, 5627, 0, SIG_0) = 0
> --- SIGCHLD (Child exited) @ 0 (0) ---
> wait4(5627, [{WIFSTOPPED(s) && WSTOPSIG(s) == 133}], WSTOPPED, NULL) = 5627
> ptrace(PTRACE_SETREGS, 5627, 0, 0x60e9f188) = 0
> ptrace(PTRACE_SETFPREGS, 5627, 0, 0x60e9f260) = 0
> ptrace(PTRACE_SYSCALL, 5627, 0, SIG_0) = 0
> ...
>
>
> (2) Sample trace of Asterisk's demise:
> 1785 clone(child_stack=0,
> flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD,
> child_tidptr=0x4001f640) = 1786
> 1785 exit_group(0) = ?
> 1786 setsid() = 1786
> 1786 chdir("/") = 0
> 1786 open("/dev/null", O_RDWR) = 3
> 1786 fstat(3, {st_mode=S_IFCHR|0666, st_rdev=makedev(1, 3), ...}) = 0
> 1786 dup2(3, 0) = 0
> 1786 dup2(3, 1) = 1
> 1786 dup2(3, 2) = 2
> 1786 close(3) = 0
> 1786 unlink("/var/run/asterisk/asterisk.pid") = 0
> 1786 open("/var/run/asterisk/asterisk.pid", O_WRONLY|O_CREAT|O_TRUNC, 0666)
> = 3
> 1786 fstat(3, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
> 1786 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
> 0) = 0x40019000
> 1786 write(3, "1786\n", 5) = 5
> 1786 close(3) = 0
> 1786 munmap(0x40019000, 4096) = 0
> 1786 mmap(NULL, 266240, PROT_READ|PROT_WRITE,
> MAP_PRIVATE|MAP_ANONYMOUS|0x40, -1, 0) = 0x40020000
> 1786 mprotect(0x40020000, 4096, PROT_NONE) = 0
> 1786 clone(child_stack=0x40060280,
> flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID|CLONE_DETACHED,
> parent_tidptr=0x400609f0, tls=0x40060960, child_tidptr=0x400609f0) = 1787
> 1786 nanosleep({0, 100000}, <unfinished ...>
> 1787 --- SIGSEGV (Segmentation fault) @ 0 (0) ---
>
>
> (3) Sample trace of Apache:
> ...
> 945 rt_sigaction(SIGSEGV, {0x43ace0, [], SA_RESTORER|SA_ONESHOT,
> 0x4113f410}, NULL, 8) = 0
> 945 rt_sigaction(SIGBUS, {0x43ace0, [], SA_RESTORER|SA_ONESHOT, 0x4113f410},
> NULL, 8) = 0
> ...
> 945 select(0, NULL, NULL, NULL, {1, 0}) = 0 (Timeout)
> 945 clone(child_stack=0,
> flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD,
> child_tidptr=0x40025a60) = 961
> 945 wait4(-1, 0x7f7fc3267c, WNOHANG|WSTOPPED, NULL) = 0
> 945 select(0, NULL, NULL, NULL, {1, 0} <unfinished ...>
> 961 rt_sigaction(SIGTERM, {0x446b10, [], SA_RESTORER|SA_INTERRUPT,
> 0x4113f410}, {0x444fd0, [], SA_RESTORER, 0x4113f410}, 8) = 0
> 961 geteuid() = 0
> 961 setgid(33) = 0
> 961 open("/proc/sys/kernel/ngroups_max", O_RDONLY) = 8
> 961 read(8, "65536\n", 31) = 6
> 961 close(8) = 0
> 961 open("/etc/group", O_RDONLY) = 8
> 961 fcntl(8, F_GETFD) = 0
> 961 fcntl(8, F_SETFD, FD_CLOEXEC) = 0
> 961 lseek(8, 0, SEEK_CUR) = 0
> 961 fstat(8, {st_mode=S_IFREG|0644, st_size=485, ...}) = 0
> 961 mmap(NULL, 485, PROT_READ, MAP_SHARED, 8, 0) = 0x40019000
> 961 lseek(8, 485, SEEK_SET) = 485
> 961 fstat(8, {st_mode=S_IFREG|0644, st_size=485, ...}) = 0
> 961 munmap(0x40019000, 485) = 0
> 961 close(8) = 0
> 961 setgroups(1, [33]) = 0
> 961 geteuid() = 0
> 961 setuid(33) = 0
> 961 rt_sigprocmask(SIG_SETMASK, ~[ILL TRAP ABRT BUS FPE SEGV USR2 PIPE SYS
> RTMIN RT_1], NULL, 8) = 0
> 961 mmap(NULL, 8392704, PROT_READ|PROT_WRITE,
> MAP_PRIVATE|MAP_ANONYMOUS|0x40, -1, 0) = 0x43981000
> 961 mprotect(0x43981000, 4096, PROT_NONE) = 0
> 961 clone(child_stack=0x44181280,
> flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETT
> ID|LONE_CHILD_CLEARTID|CLONE_DETACHED, parent_tidptr=0x441819f0,
> tls=0x44181960, child_tidptr=0x441819f0) = 962
> 961 rt_sigprocmask(SIG_UNBLOCK, [TERM], NULL, 8) = 0
> 961 rt_sigaction(SIGTERM, {0x445040, [], SA_RESTORER|SA_INTERRUPT,
> 0x4113f410}, {0x446b10, [], SA_RESTORER|SA_INTERRUPT, 0x4113f410}, 8) = 0
> 961 read(4, <unfinished ...>
> 962 --- SIGSEGV (Segmentation fault) @ 0 (0) ---
> 962 chdir("/etc/apache2") = 0
> 962 rt_sigaction(SIGSEGV, {SIG_DFL}, {SIG_DFL}, 8) = 0
> 962 kill(961, SIGSEGV) = 0
> 961 <... read resumed> 0x7f7fc32657, 1) = ? ERESTARTSYS (To be restarted)
> 961 --- SIGSEGV (Segmentation fault) @ 0 (0) ---
> 962 +++ killed by SIGSEGV +++
> 945 <... select resumed> ) = ? ERESTARTNOHAND (To be restarted)
> 945 --- SIGCHLD (Child exited) @ 0 (0) ---
> 945 select(0, NULL, NULL, NULL, {1, 0}) = 0 (Timeout)
> 945 wait4(-1, [{WIFSIGNALED(s) && WTERMSIG(s) == SIGSEGV}],
> WNOHANG|WSTOPPED, NULL) = 961
> 945 write(6, "[Tue Feb 20 02:46:59 2007] [notice] child pid 961 exit signal
> Segmentation fault (11)\n", 86) = 86
> 945 wait4(-1, 0x7f7fc3267c, WNOHANG|WSTOPPED, NULL) = 0
> 945 select(0, NULL, NULL, NULL, {1, 0}) = 0 (Timeout)
> 945 clone(child_stack=0,
> flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD,
> child_tidptr=0x40025a60) = 963
> ... -- a la groundhog day
>
> Even if you can't help, thanks for reading this far!
>
> jez
>
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