Bug 225583
| Summary: | UML on FC6 fails because of utrace patch | ||
|---|---|---|---|
| Product: | [Fedora] Fedora | Reporter: | JuanJo Ciarlante <jjo> |
| Component: | kernel | Assignee: | Roland McGrath <roland> |
| Status: | CLOSED WORKSFORME | QA Contact: | Brian Brock <bbrock> |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | 6 | CC: | cebbert, davej, wtogami |
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2007-09-04 20:45:23 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
I forgot metioning I did more testing:
I did the following tests, based on released utrace patch (OK means UML runs
w/no problem, BAD means UML stops after VFS root mounting )
#1 2.6.18.6 vanilla: OK
#2 2.6.18.6+utrace,CONFIG_{UP}TRACE=y : BAD (same behaviour as FC6 stock kernel)
#3 2.6.18.6+utrace,CONFIG_{UP}TRACE unset: BAD (idem)
Curiously, #3 did the very same as #2 (even wrt strace process disposition
and strace "behaviour"), I'd expected #3 to simply fail at boot with
EINVAL or alike (given that no ptrace support was compiled in).
Regards
Would it be possible for you to test against vanilla 2.6.20? The utrace patches in http://redhat.com/~roland/utrace/2.6-current/ are now against 2.6.20, and have some fixes not in the 2.6.18 backport. If utrace is breaking UML, I'll need to debug it against the current kernel. I've tested against 2.6.20: SAME (bad) behaviour as 2.6.18.6. FYI ss with previous kernels, I've downloaded 2.6.20 vanilla, copied .config make && make install && boot ; later applied utrace patch , edited EXTRA_VERSION && ... && boot. According to Jeff Dike "UML runs on the utrace in -mm (i.e. utrace on the host), which it didn't with several Fedora kernels." http://lkml.org/lkml/2007/2/20/299 Indeed, apparently problems with UML are now seen only on a CONFIG_PREEMPT=y kernel, which Fedora does not ship. However, it may be only the luck of the timing, as the bug biting UML was never isolated. Several old bugs that might have affected this have been fixed. Reopen if the problem reoccurs. |
Description of problem: Running any user-mode-linux kernel (did try self compiled 2.6.17 and dloaded 2.6.18, 2.6.19.2 umls) fails: it boots and stops responding after "VFS: Mounted root (ext3 filesystem) readonly." I tracked back and narrowed the kernel versions where the problem started to show: OK: kernel-smp-2.6.17-1.2187_FC5 (last FC5 upd. kernel I know to run ok) BAD: kernel-smp-2.6.18-1.2239.fc5 (IIRC 1st non-working FC5 kernel) BAD: kernel-2.6.19-1.2895.fc6 (current FC6 kernel) Note: this is a FC6 uptodate distro, booted with these 3 diff. kernels. Because those FC5 kernels have same selinux policyversion , FC6 "environment" runs ok AFAICT. To see at least if the command gets "enough" CPU to halt the UML, I tried: ./linux init=/sbin/halt -f It didn't, "ps lx" on the host shows: $ ps lx 0 240 4284 4152 15 0 33000 11000 - R+ pts/1 3:31 ./linux (Jj9kkn) /sbin/halt] 1 240 4293 4284 25 0 33000 11000 - S+ pts/1 0:00 ./linux (Jj9kkn) /sbin/halt] 1 240 4294 4284 24 0 33000 11000 - S+ pts/1 0:00 ./linux (Jj9kkn) /sbin/halt] 1 240 4295 4284 15 0 33000 11000 - S+ pts/1 0:00 ./linux (Jj9kkn) /sbin/halt] 1 240 4296 4284 15 0 60 56 - R+ pts/1 2:42 [linux] , where cpu time for those "R+" procs almost equals wall time; strace'ing repeats eternally these lines: $ strace -p 4284 -- SIGCHLD (Child exited) @ 0 (0) --- waitpid(4296, [{WIFSTOPPED(s) && WSTOPSIG(s) == SIGSEGV}], WSTOPPED) = 4296 ptrace(PTRACE_GETREGS, 4296, 0, 0xa06ab82c) = 0 ptrace(PTRACE_GETFPXREGS, 4296, 0, 0xa06ab8dc) = 0 ptrace(PTRACE_CONT, 4296, 0, SIGSEGV) = 0 : : Version-Release number of selected component (if applicable): kernel-2.6.19-1.2895.fc6 How reproducible: Check that you are running a stock FC6 kernel Compile or download an UML guest kernel (eg: http://uml.nagafix.co.uk/) and any root_fs image, boot UML: it will stop after VFS mount. Steps to Reproduce: 1. Download/compile UML guest kernel, eg: set -e wget http://uml.nagafix.co.uk/kernels/kernel32-2.6.19.2 mv kernel32-2.6.19.2 linux chmod +x linux 2. Download/build UML guest root_fs, eg: wget http://uml.nagafix.co.uk/DSL-2.2/DSL-2.2-root_fs.bz2 bunzip2 DSL-2.2-root_fs.bz2 mv DSL-2.2-root_fs root_fs 3. ./linux Actual results: UML stops actually running after: "VFS: Mounted root (ext3 filesystem) readonly." Expected results: To continue normal guest boot (run /sbin/init) Additional info: I've posted the FULL report uml-users mailing list: http://sourceforge.net/mailarchive/forum.php?thread_id=31527621&forum_id=3647