On Mon, 2018-07-16 at 12:09 +0200, Dmitry Vyukov wrote: > On Fri, Jul 13, 2018 at 11:58 PM, Andrew Morton > <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > On Fri, 13 Jul 2018 14:39:02 -0700 syzbot < > > syzbot+cce9ef2dd25246f815ee@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > > Hello, > > > > > > syzbot found the following crash on: > > > > hm, I don't think I've seen an "unexpected reboot" report before. > > > > Can you expand on specifically what happened here? Did the machine > > simply magically reboot itself? Or did an external monitor whack it, > > or... > > We put some user-space workload (not involving reboot syscall), and > the machine suddenly rebooted. We don't know what triggered the > reboot, we only see the consequences. We've seen few such bugs before, > e.g.: > https://syzkaller.appspot.com/bug?id=4f1db8b5e7dfcca55e20931aec0ee707c5cafc99 > Usually it involves KVM. Potentially it's a bug in the outer > kernel/VMM, it may or may not be present in tip kernel. I have been using GCE with my custom VirtualBox -created reiser4 root fs VMs since at least 2018, long term mainly as web servers with LAMP / LEMP -- including some Ruby apps with Postgresql -- and short term to build our Debian Linux kernels. I have not experienced 'suddenly rebooted' scenarios. Note that I have been usin Intel CPUs at the Los Angeles zone us-west2-a, as well as us-east1-b zone, and AMD Epyc CPUs at us-central1-a zone, without abnormalities (other than it's becoming more expensive ;-) As a matter of fact, I am currently testing a Debian'ized reiser4 (AMD Epyc - flavored reizer4 label) -enabled Linux kernel 5.10.15-2 which has logged 17 days +hours already and sustaining most of the apps already mentioned. < https://metztli.it/buster/r4-5.10.15-gce.png > > > > > Does this test distinguish from a kernel which simply locks up? > > Yes. If you look at the log: > > https://syzkaller.appspot.com/x/log.txt?x=17c6a6d0400000 > > We've booted the machine, started running a program, and them boom! it > reboots without any other diagnostics. It's not a hang. > > > > > > HEAD commit: 1e4b044d2251 Linux 4.18-rc4 > > > git tree: upstream > > > console output: https://syzkaller.appspot.com/x/log.txt?x=17c6a6d0400000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=25856fac4e580aa7 > > > dashboard link: > > > https://syzkaller.appspot.com/bug?extid=cce9ef2dd25246f815ee > > > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > > syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=165012c2400000 > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1571462c400000 > > > > I assume the "C reproducer" is irrelevant here. > > > > Is it reproducible? > > Yes, it is reproducible and the C reproducer is relevant. > If syzbot provides a reproducer, it means that it booted a clean > machine, run the provided program (nothing else besides typical init > code and ssh/scp invocation) and that's the kernel output it observed > running this exact program. > However in this case, the exact setup can be relevant. syzbot uses GCE > VMs, it may or may not reproduce with other VMMs/physical hardware, > sometimes such bugs depend on exact CPU type. > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > > Reported-by: syzbot+cce9ef2dd25246f815ee@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > > > output_len: 0x00000000092459b0 > > > kernel_total_size: 0x000000000a505000 > > > trampoline_32bit: 0x000000000009d000 > > > > > > Decompressing Linux... Parsing ELF... done. > > > Booting the kernel. > > > [ 0.000000] Linux version 4.18.0-rc4+ (syzkaller@ci) (gcc version 8.0.1 > > > 20180413 (experimental) (GCC)) #138 SMP Mon Jul 9 10:45:11 UTC 2018 > > > [ 0.000000] Command line: BOOT_IMAGE=/vmlinuz root=/dev/sda1 > > > console=ttyS0 earlyprintk=serial vsyscall=native rodata=n > > > ftrace_dump_on_oops=orig_cpu oops=panic panic_on_warn=1 nmi_watchdog=panic > > > panic=86400 workqueue.watchdog_thresh=140 kvm-intel.nested=1 > > > > > > ... > > > > > > regulatory database > > > [ 4.519364] cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7' > > > [ 4.520839] platform regulatory.0: Direct firmware load for > > > regulatory.db failed with error -2 > > > [ 4.522155] cfg80211: failed to load regulatory.db > > > [ 4.522185] ALSA device list: > > > [ 4.523499] #0: Dummy 1 > > > [ 4.523951] #1: Loopback 1 > > > [ 4.524389] #2: Virtual MIDI Card 1 > > > [ 4.825991] input: ImExPS/2 Generic Explorer Mouse as > > > /devices/platform/i8042/serio1/input/input4 > > > [ 4.829533] md: Waiting for all devices to be available before > > > autodetect > > > [ 4.830562] md: If you don't use raid, use raid=noautodetect > > > [ 4.835237] md: Autodetecting RAID arrays. > > > [ 4.835882] md: autorun ... > > > [ 4.836364] md: ... autorun DONE. > > > > Can we assume that the failure occurred in or immediately after the MD code, > > or might some output have been truncated? > > > > It would be useful to know what the kernel was initializing immediately > > after MD. Do you have a kernel log for the same config when the kerenl > > didn't fail? Or maybe enable initcall_debug? > > > > -- > > You received this message because you are subscribed to the Google Groups > > "syzkaller-bugs" group. > > To unsubscribe from this group and stop receiving emails from it, send an > > email to syzkaller-bugs+unsubscribe@xxxxxxxxxxxxxxxx. > > To view this discussion on the web visit > > https://groups.google.com/d/msgid/syzkaller-bugs/20180713145811.683ffd0043cac26a5a5af725%40linux-foundation.org > > . > > For more options, visit https://groups.google.com/d/optout. (saw your last message of just a couple of hours and...) Hope provided info helps. Best Professional Regards. -- -- Jose R R http://metztli.it ----------------------------------------------------------------------- Download Metztli Reiser4: Debian Buster w/ Linux 5.9.16 AMD64 ----------------------------------------------------------------------- feats ZSTD compression https://sf.net/projects/metztli-reiser4/ ----------------------------------------------------------------------- or SFRN 5.1.3, Metztli Reiser5 https://sf.net/projects/debian-reiser4/ ----------------------------------------------------------------------- Official current Reiser4 resources: https://reiser4.wiki.kernel.org/
