On Mon, Nov 15, 2021 at 3:27 PM Baoquan He <bhe@xxxxxxxxxx> wrote: > > Hi, > > On 11/13/21 at 10:40am, Dongliang Mu wrote: > > Hi all KDUMP maintainers, > > > > I would like to generate a kernel dump within QEMU VM. > > > > 1. I reproduced the kernel crash [1] in QEMU VM. The QEMU startup > > script is as follows: > > > > qemu-system-x86_64 \ > > -kernel $KERNEL/arch/x86/boot/bzImage \ > > -append "console=ttyS0 root=/dev/sda debug earlyprintk=serial slub_debug=QUZ"\ > > -hda $IMAGE/stretch.img \ > > -net user,hostfwd=tcp::10021-:22 -net nic \ > > -enable-kvm \ > > -nographic \ > > -m 2G \ > > -smp 2 \ > > -pidfile vm.pid \ > > 2>&1 | tee vm.log > > > > The stretch.img is generated by Syzkaller script [1]. -kernel option > > is convenient for loading any other kernels. > > > > 2. As the .config already has the essential > > configuration(CONFIG_KEXEC, CONFIG_CRASH_DUMP, CONFIG_DEBUG_INFO), I > > did not change this configuration file. > > > > 3. I installed kdump-tools crash kexec-tools makedumpfile > > linux-image-4.9.0-13-amd64 in the stretch.img. Here I installed > > linux-image-4.9.0-13-amd64 because there is no default kernel in /boot > > directory. And to make kdump-tools working, I modify > > /etc/default/kdump-tools in the following: > > > > KDUMP_INITRD=/boot/initrd.img-4.9.0-13-amd64 > > KDUMP_KERNEL=/boot/vmlinuz-4.9.0-13-amd64 > > What distros are you using? Asking this because I am sure you are not > using Fedora/RHEL OS. The implementation of kdump tools is different in > each distros, even though the mechanims in kdump code is the same. > I am using Debian stretch as the guest OS. So kdump-tools kexec makedumpfile is all from Debian. > When we try to get help from upstream, considering and asking good question > is very important for getting quick response and effective help. > > Thanks > Baoquan > > > > > 4. I append "crashkernel=384M-:128M" to the command line in the > > startup script of QEMU. > > > > 5. After rebooting, kdump service can start successfully, and the > > kdump-config shows: > > > > root@syzkaller:~# kdump-config show > > DUMP_MODE: kdump > > USE_KDUMP: 1 > > KDUMP_SYSCTL: kernel.panic_on_oops=1 > > KDUMP_COREDIR: /var/crash > > crashkernel addr: 0x77000000 > > /boot/vmlinuz-4.9.0-13-amd64 > > kdump initrd: > > /boot/initrd.img-4.9.0-13-amd64 > > current state: ready to kdump > > > > kexec command: > > /sbin/kexec -p --command-line="earlyprintk=serial oops=panic > > panic_on_warn=1 nmi_watchdog=panic panic=86400 net.ifnames=0 > > sysctl.kernel.hung_task_all_cpu_backtrace=1 ima_policy=tcb > > kvm-intel.nested=1 nf-conntrack-ftp.ports=20000 > > nf-conntrack-tftp.ports=20000 nf-conntrack-sip.ports=20000 > > nf-conntrack-irc.ports=20000 nf-conntrack-sane.ports=20000 > > vivid.n_devs=16 vivid.multiplanar=1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2 > > netrom.nr_ndevs=16 rose.rose_ndevs=16 spec_store_bypass_disable=prctl > > numa=fake=2 nopcid dummy_hcd.num=8 binder.debug_mask=0 > > rcupdate.rcu_expedited=1 root=/dev/sda console=ttyS0 vsyscall=native > > watchdog_thresh=55 workqueue.watchdog_thresh=140 console=ttyS0 > > root=/dev/sda debug earlyprintk=serial slub_debug=QUZ irqpoll > > nr_cpus=1 nousb systemd.unit=kdump-tools.service > > ata_piix.prefer_ms_hyperv=0" --initrd=/boot/initrd.img-4.9.0-13-amd64 > > /boot/vmlinuz-4.9.0-13-amd64 > > > > 6. When I execute the PoC, the current kernel crashes and then reboots > > into the dump-capture kernel. However, the kernel log shows, it is in > > emergency mode, > > > > You are in emergency mode. After logging in, type "journalctl -xb" to view > > system logs, "systemctl reboot" to reboot, "systemctl default" or ^D to > > try again to boot into default mode. > > > > Finally, I would like to ask several questions: > > 1) is the emergency mode due to the incorrect command line? > > 2) is this the right way to generate kernel dump from QEMU VM? > > 3) Any comments on the above procedures? > > > > Thanks very much in advance. > > > > [1] general protection fault in reiserfs_security_init > > (https://syzkaller.appspot.com/bug?id=8abaedbdeb32c861dc5340544284167dd0e46cde) > > > > [2] https://github.com/google/syzkaller/blob/master/tools/create-image.sh > > > > -- > > My best regards to you. > > > > No System Is Safe! > > Dongliang Mu > > _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
