Hi, I've been running some x86_64 guests with the new ptrace_fixes patch for the last few days. For the most part everything has been running very well, but I have encountered a couple of problems running the apache2 server. The first problem is documented here.
Ordinarily apache2 runs just fine, but when you configure it to run with ssl configured (mod_ssl) it starts to get hit by a SIGSEGV about once every second. This condition is triggered as soon as the first request arrives. Note, that this initial request does not need to be on port 443 (HTTPS), a normal HTTP request triggers it as well. My Host is a debian stock 2.6.18-3-amd64. My Guest is 2.6.20 built from kernel.org sources with the following six patches applied: [patches from 2007-01-23] 5/7: style fixes in startup code 6/7: libc-dependent code should call libc 7/7: fix style violations [patches from 2007-02-08] 1/3: Fix error output during early boot 2/3: x86_64 thread fixes 3/3: x86_64 ptrace fixes I've taken straces running both with and without mod_ssl loaded. The major difference appears to be that epoll is used when mod_ssl is loaded. The following shows what happens when I issue something like: curl --head http://my.pache.server == Output without mod_ssl == 842 02:35:43 accept(3, <unfinished ...> ... 812 02:35:53 select(0, NULL, NULL, NULL, {1, 0}) = 0 (Timeout) 812 02:35:54 wait4(-1, 0x7f7ffabcdc, WNOHANG|WSTOPPED, NULL) = 0 812 02:35:54 select(0, NULL, NULL, NULL, {1, 0} <unfinished ...> 842 02:35:54 <... accept resumed> {sa_family=AF_INET, sin_port=htons(53125), sin_addr=inet_addr("10.0.0.22")}, [17179869200]) = 10 842 02:35:54 futex(0x64124c, FUTEX_WAKE, 1) = 1 841 02:35:54 <... futex resumed> ) = 0 842 02:35:54 accept(3, <unfinished ...> 841 02:35:54 futex(0x6411f8, FUTEX_WAKE, 1) = 0 841 02:35:54 getsockname(10, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("10.0.0.190")}, [17179869200]) = 0 ... 841 02:35:54 futex(0x64124c, FUTEX_WAIT, 27, NULL <unfinished ...> 812 02:35:55 <... select resumed> ) = 0 (Timeout) 812 02:35:55 wait4(-1, 0x7f7ffabcdc, WNOHANG|WSTOPPED, NULL) = 0 812 02:35:55 select(0, NULL, NULL, NULL, {1, 0}) = 0 (Timeout) == END TRACE == == Output with mod_ssl == 904 03:19:56 epoll_create(2) = 13 904 03:19:56 epoll_ctl(13, EPOLL_CTL_ADD, 4, {EPOLLIN, {u32=6031368, u64=6031368}}) = 0 904 03:19:56 epoll_ctl(13, EPOLL_CTL_ADD, 3, {EPOLLIN, {u32=6031416, u64=6031416}}) = 0 904 03:19:56 rt_sigprocmask(SIG_UNBLOCK, [HUP], NULL, 8) = 0 904 03:19:56 rt_sigaction(SIGHUP, {0x445040, [], SA_RESTORER|SA_INTERRUPT, 0x4113f410}, {0x445000, [HUP USR1], SA_RESTORER, 0x4113f410}, 8) = 0 904 03:19:56 semop(65536, 0x40df2da0, 1) = 0 904 03:19:56 epoll_wait(13, <unfinished ...> ... 870 03:20:43 select(0, NULL, NULL, NULL, {1, 0}) = 0 (Timeout) 870 03:20:44 wait4(-1, 0x7f7f907e2c, WNOHANG|WSTOPPED, NULL) = 0 870 03:20:44 select(0, NULL, NULL, NULL, {1, 0} <unfinished ...> 904 03:20:45 <... epoll_wait resumed> {{EPOLLIN, {u32=0, u64=0}}}, 2, 4294967295) = 1 904 03:20:45 --- SIGSEGV (Segmentation fault) @ 0 (0) --- 904 03:20:45 chdir("/etc/apache2") = 0 904 03:20:45 rt_sigaction(SIGSEGV, {SIG_DFL}, {SIG_DFL}, 8) = 0 904 03:20:45 kill(871, SIGSEGV) = 0 871 03:20:45 <... read resumed> 0x7f7f907de7, 1) = ? ERESTARTSYS (To be restarted) 871 03:20:45 --- SIGSEGV (Segmentation fault) @ 0 (0) --- 904 03:20:45 +++ killed by SIGSEGV +++ 875 03:20:45 <... futex resumed> ) = -1 EINTR (Interrupted system call) 877 03:20:45 <... futex resumed> ) = -1 EINTR (Interrupted system call) ... 875 03:20:45 +++ killed by SIGSEGV +++ 877 03:20:45 +++ killed by SIGSEGV +++ == END TRACE == Soon after this it enters a loop of cloning batches of processes (threads?) only to have them killed off by a SIGSEGV. epoll is actually used when mod_ssl is not loaded as well, but it's used very sparingly (a few calls to epoll_create and epoll_ctl). Apache2 isn't shutting down very cleanly at the moment (as I hope to highlight in follow up post), so I'm hoping there's a correlation here. jez ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user
