That is what is logged into /var/log/kern.log on Vivid i386 running 3.18.0.4 (canonical-kernel-team ppa), and using ext4 partitions for lts/current/dev ubuntu os, /home is on ext3 (aka sda3) (there is no other format around on that pc) : Nov 25 17:54:35 u32 kernel: [29589.094552] EXT4-fs (sda3): unable to read superblock Nov 25 17:54:35 u32 kernel: [29589.095944] EXT4-fs (sda3): unable to read superblock Nov 25 17:54:35 u32 kernel: [29589.097316] EXT4-fs (sda3): unable to read superblock Nov 25 17:54:35 u32 kernel: [29589.098783] FAT-fs (sda3): bogus number of reserved sectors Nov 25 17:54:35 u32 kernel: [29589.098786] FAT-fs (sda3): Can't find a valid FAT filesystem Nov 25 17:54:35 u32 kernel: [29589.103508] XFS (sda3): Invalid superblock magic number Nov 25 17:54:35 u32 kernel: [29589.106556] FAT-fs (sda3): bogus number of reserved sectors Nov 25 17:54:35 u32 kernel: [29589.106559] FAT-fs (sda3): Can't find a valid FAT filesystem Nov 25 17:54:35 u32 kernel: [29589.111064] MINIX-fs: unable to read superblock Nov 25 17:54:35 u32 kernel: [29589.112470] attempt to access beyond end of device Nov 25 17:54:35 u32 kernel: [29589.112473] sda3: rw=16, want=3, limit=2 Nov 25 17:54:35 u32 kernel: [29589.112476] hfsplus: unable to find HFS+ superblock Nov 25 17:54:35 u32 kernel: [29589.113914] qnx4: no qnx4 filesystem (no root dir). Nov 25 17:54:35 u32 kernel: [29589.115265] ufs: You didn't specify the type of your ufs filesystem Nov 25 17:54:35 u32 kernel: [29589.115265] Nov 25 17:54:35 u32 kernel: [29589.115265] mount -t ufs -o ufstype=sun|sunx86|44bsd|ufs2|5xbsd|old|hp|nextstep|nextstep-cd|openstep ... Nov 25 17:54:35 u32 kernel: [29589.115265] Nov 25 17:54:35 u32 kernel: [29589.115265] >>>WARNING<<< Wrong ufstype may corrupt your filesystem, default is ufstype=old Nov 25 17:54:35 u32 kernel: [29589.118051] hfs: can't find a HFS filesystem on dev sda3 Nov 25 17:54:55 u32 kernel: [29609.377181] EXT4-fs (sda3): unable to read superblock Nov 25 17:54:55 u32 kernel: [29609.378565] EXT4-fs (sda3): unable to read superblock Nov 25 17:54:55 u32 kernel: [29609.379947] EXT4-fs (sda3): unable to read superblock Nov 25 17:54:55 u32 kernel: [29609.381458] FAT-fs (sda3): bogus number of reserved sectors Nov 25 17:54:55 u32 kernel: [29609.381462] FAT-fs (sda3): Can't find a valid FAT filesystem Nov 25 17:54:55 u32 kernel: [29609.386248] XFS (sda3): Invalid superblock magic number Nov 25 17:54:55 u32 kernel: [29609.389318] FAT-fs (sda3): bogus number of reserved sectors Nov 25 17:54:55 u32 kernel: [29609.389322] FAT-fs (sda3): Can't find a valid FAT filesystem Nov 25 17:54:55 u32 kernel: [29609.395129] MINIX-fs: unable to read superblock Nov 25 17:54:55 u32 kernel: [29609.396744] attempt to access beyond end of device Nov 25 17:54:55 u32 kernel: [29609.396748] sda3: rw=16, want=3, limit=2 Nov 25 17:54:55 u32 kernel: [29609.396750] hfsplus: unable to find HFS+ superblock Nov 25 17:54:55 u32 kernel: [29609.398259] qnx4: no qnx4 filesystem (no root dir). Nov 25 17:54:55 u32 kernel: [29609.399623] ufs: You didn't specify the type of your ufs filesystem Nov 25 17:54:55 u32 kernel: [29609.399623] Nov 25 17:54:55 u32 kernel: [29609.399623] mount -t ufs -o ufstype=sun|sunx86|44bsd|ufs2|5xbsd|old|hp|nextstep|nextstep-cd|openstep ... Nov 25 17:54:55 u32 kernel: [29609.399623] Nov 25 17:54:55 u32 kernel: [29609.399623] >>>WARNING<<< Wrong ufstype may corrupt your filesystem, default is ufstype=old Nov 25 17:54:55 u32 kernel: [29609.402391] hfs: can't find a HFS filesystem on dev sda3 ************************ NOTE********************** these logged lines are written when the system is shuted down by the user: running a gnome-shell session and hitting the 'shutdown' gui icon from the 'shutdown' icon on top right tray. Why all that mess when a system is closed ? (system booted with systemd-boot) Looks like a package (os-prober ? or else) is running some 'starting' boot routines it never should be calling at closed time. **************************************************** What happen on next cold boot ? A KERNEL PANIC Nov 26 07:36:26 u32 kernel: [ 42.058213] nvidia 0000:06:00.0: irq 32 for MSI/MSI-X Nov 26 07:36:27 u32 kernel: [ 42.806927] ------------[ cut here ]------------ Nov 26 07:36:27 u32 kernel: [ 42.806948] WARNING: CPU: 3 PID: 818 at /build/buildd/linux-3.18.0/drivers/gpu/drm/drm_ioctl.c:143 drm_setversion+0x185/0x190 [drm]() Nov 26 07:36:27 u32 kernel: [ 42.807020] No drm_driver.set_busid() implementation provided by nv_drm_driver [nvidia]. Use drm_dev_set_unique() to set the unique name explicitly. Nov 26 07:36:27 u32 kernel: [ 42.807021] Modules linked in: binfmt_misc ip6t_REJECT nf_reject_ipv6 nf_log_ipv6 xt_hl ip6t_rt nf_conntrack_ipv6 nf_defrag_ipv6 ipt_REJECT nf_reject_ipv4 nf_log_ipv4 nf_log_common xt_LOG xt_limit xt_tcpudp xt_addrtype nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack ip6table_filter ip6_tables nf_conntrack_netbios_ns nf_conntrack_broadcast nf_nat_ftp nf_nat nf_conntrack_ftp nf_conntrack iptable_filter ip_tables x_tables nvidia(POE) drm serio_raw lpc_ich shpchp snd_hda_codec_hdmi 8250_fintek coretemp kvm_intel asus_atk0110 kvm snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel snd_hda_controller snd_hda_codec snd_hwdep snd_pcm snd_seq_midi i82975x_edac edac_core snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device snd_timer snd soundcore mac_hid parport_pc ppdev lp parport autofs4 hid_generic usbhid hid pata_acpi ahci pata_jmicron libahci sky2 Nov 26 07:36:27 u32 kernel: [ 42.807074] CPU: 3 PID: 818 Comm: Xorg Tainted: P OE 3.18.0-4-generic #5-Ubuntu Nov 26 07:36:27 u32 kernel: [ 42.807076] Hardware name: ASUSTEK COMPUTER INC P5W DH Deluxe/P5W DH Deluxe, BIOS 3002 07/22/2010 Nov 26 07:36:27 u32 kernel: [ 42.807078] 00000003 00000000 f6859dd4 c16c3ad6 f6859e18 f6859e08 c105f9b2 f84af000 Nov 26 07:36:27 u32 kernel: [ 42.807083] f6859e34 00000332 f84aef64 0000008f f848a7e5 0000008f f848a7e5 f6859e8c Nov 26 07:36:27 u32 kernel: [ 42.807088] f6612400 ffffffea f6859e20 c105fa03 00000009 f6859e18 f84af000 f6859e34 Nov 26 07:36:27 u32 kernel: [ 42.807094] Call Trace: Nov 26 07:36:27 u32 kernel: [ 42.807101] [] dump_stack+0x41/0x52 Nov 26 07:36:27 u32 kernel: [ 42.807105] [] warn_slowpath_common+0x82/0xa0 Nov 26 07:36:27 u32 kernel: [ 42.807117] [] ? drm_setversion+0x185/0x190 [drm] Nov 26 07:36:27 u32 kernel: [ 42.807127] [] ? drm_setversion+0x185/0x190 [drm] Nov 26 07:36:27 u32 kernel: [ 42.807130] [] warn_slowpath_fmt+0x33/0x40 Nov 26 07:36:27 u32 kernel: [ 42.807140] [] drm_setversion+0x185/0x190 [drm] Nov 26 07:36:27 u32 kernel: [ 42.807151] [] ? drm_noop+0x40/0x40 [drm] Nov 26 07:36:27 u32 kernel: [ 42.807161] [] drm_ioctl+0x2bc/0x560 [drm] Nov 26 07:36:27 u32 kernel: [ 42.807171] [] ? drm_noop+0x40/0x40 [drm] Nov 26 07:36:27 u32 kernel: [ 42.807176] [] ? user_path_at_empty+0x49/0x80 Nov 26 07:36:27 u32 kernel: [ 42.807180] [] ? _copy_to_user+0x26/0x30 Nov 26 07:36:27 u32 kernel: [ 42.807183] [] ? do_filp_open+0x31/0x90 Nov 26 07:36:27 u32 kernel: [ 42.807193] [] ? drm_getmap+0xc0/0xc0 [drm] Nov 26 07:36:27 u32 kernel: [ 42.807196] [] do_vfs_ioctl+0x302/0x510 Nov 26 07:36:27 u32 kernel: [ 42.807199] [] ? final_putname+0x1d/0x40 Nov 26 07:36:27 u32 kernel: [ 42.807203] [] ? final_putname+0x1d/0x40 Nov 26 07:36:27 u32 kernel: [ 42.807205] [] ? putname+0x24/0x40 Nov 26 07:36:27 u32 kernel: [ 42.807209] [] ? do_sys_open+0x19d/0x260 Nov 26 07:36:27 u32 kernel: [ 42.807212] [] SyS_ioctl+0x60/0x90 Nov 26 07:36:27 u32 kernel: [ 42.807216] [] sysenter_do_call+0x12/0x12 Nov 26 07:36:27 u32 kernel: [ 42.807218] ---[ end trace 02c9e0eed197c80a ]--- Nov 26 07:36:27 u32 kernel: [ 42.807221] ------------[ cut here ]------------ Nov 26 07:36:27 u32 kernel: [ 42.807231] WARNING: CPU: 3 PID: 818 at /build/buildd/linux-3.18.0/drivers/gpu/drm/drm_ioctl.c:143 drm_setversion+0x185/0x190 [drm]() Nov 26 07:36:27 u32 kernel: [ 42.807283] No drm_driver.set_busid() implementation provided by nv_drm_driver [nvidia]. Use drm_dev_set_unique() to set the unique name explicitly. Nov 26 07:36:27 u32 kernel: [ 42.807284] Modules linked in: binfmt_misc ip6t_REJECT nf_reject_ipv6 nf_log_ipv6 xt_hl ip6t_rt nf_conntrack_ipv6 nf_defrag_ipv6 ipt_REJECT nf_reject_ipv4 nf_log_ipv4 nf_log_common xt_LOG xt_limit xt_tcpudp xt_addrtype nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack ip6table_filter ip6_tables nf_conntrack_netbios_ns nf_conntrack_broadcast nf_nat_ftp nf_nat nf_conntrack_ftp nf_conntrack iptable_filter ip_tables x_tables nvidia(POE) drm serio_raw lpc_ich shpchp snd_hda_codec_hdmi 8250_fintek coretemp kvm_intel asus_atk0110 kvm snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel snd_hda_controller snd_hda_codec snd_hwdep snd_pcm snd_seq_midi i82975x_edac edac_core snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device snd_timer snd soundcore mac_hid parport_pc ppdev lp parport autofs4 hid_generic usbhid hid pata_acpi ahci pata_jmicron libahci sky2 Nov 26 07:36:27 u32 kernel: [ 42.807328] CPU: 3 PID: 818 Comm: Xorg Tainted: P W OE 3.18.0-4-generic #5-Ubuntu Nov 26 07:36:27 u32 kernel: [ 42.807330] Hardware name: ASUSTEK COMPUTER INC P5W DH Deluxe/P5W DH Deluxe, BIOS 3002 07/22/2010 Nov 26 07:36:27 u32 kernel: [ 42.807332] 00000003 00000000 f6859dd4 c16c3ad6 f6859e18 f6859e08 c105f9b2 f84af000 Nov 26 07:36:27 u32 kernel: [ 42.807337] f6859e34 00000332 f84aef64 0000008f f848a7e5 0000008f f848a7e5 f6859e8c Nov 26 07:36:27 u32 kernel: [ 42.807342] f6612400 ffffffea f6859e20 c105fa03 00000009 f6859e18 f84af000 f6859e34 Nov 26 07:36:27 u32 kernel: [ 42.807347] Call Trace: Nov 26 07:36:27 u32 kernel: [ 42.807350] [] dump_stack+0x41/0x52 Nov 26 07:36:27 u32 kernel: [ 42.807354] [] warn_slowpath_common+0x82/0xa0 Nov 26 07:36:27 u32 kernel: [ 42.807364] [] ? drm_setversion+0x185/0x190 [drm] Nov 26 07:36:27 u32 kernel: [ 42.807374] [] ? drm_setversion+0x185/0x190 [drm] Nov 26 07:36:27 u32 kernel: [ 42.807377] [] warn_slowpath_fmt+0x33/0x40 Nov 26 07:36:27 u32 kernel: [ 42.807388] [] drm_setversion+0x185/0x190 [drm] Nov 26 07:36:27 u32 kernel: [ 42.807398] [] ? drm_noop+0x40/0x40 [drm] Nov 26 07:36:27 u32 kernel: [ 42.807408] [] drm_ioctl+0x2bc/0x560 [drm] Nov 26 07:36:27 u32 kernel: [ 42.807418] [] ? drm_noop+0x40/0x40 [drm] Nov 26 07:36:27 u32 kernel: [ 42.807422] [] ? user_path_at_empty+0x49/0x80 Nov 26 07:36:27 u32 kernel: [ 42.807426] [] ? _copy_to_user+0x26/0x30 Nov 26 07:36:27 u32 kernel: [ 42.807428] [] ? do_filp_open+0x31/0x90 Nov 26 07:36:27 u32 kernel: [ 42.807438] [] ? drm_getmap+0xc0/0xc0 [drm] Nov 26 07:36:27 u32 kernel: [ 42.807441] [] do_vfs_ioctl+0x302/0x510 Nov 26 07:36:27 u32 kernel: [ 42.807444] [] ? final_putname+0x1d/0x40 Nov 26 07:36:27 u32 kernel: [ 42.807447] [] ? final_putname+0x1d/0x40 Nov 26 07:36:27 u32 kernel: [ 42.807450] [] ? putname+0x24/0x40 Nov 26 07:36:27 u32 kernel: [ 42.807453] [] ? do_sys_open+0x19d/0x260 Nov 26 07:36:27 u32 kernel: [ 42.807456] [] SyS_ioctl+0x60/0x90 Nov 26 07:36:27 u32 kernel: [ 42.807459] [] sysenter_do_call+0x12/0x12 Nov 26 07:36:27 u32 kernel: [ 42.807461] ---[ end trace 02c9e0eed197c80b ]--- Nov 26 07:36:34 u32 kernel: [ 49.790074] nf_conntrack: automatic helper assignment is deprecated and it will be removed soon. Use the iptables CT target to attach helpers instead. so a new cold boot is needed, and boots fine that time. ****************** Comment for Andy (apw)************ that issue is more serious than you think: simply silencing os-prober is not what is needed. as said previously, it seems that some 'booting' processes are called at shutdown time, and should never be ran. That kernel panic at 'the next cold boot' is not new and has been met since at least the latest LTS release.