Public bug reported:

to make a persistent /root, I'd usually like to rm -rf /root and make it a 
symlink to somewhere on the harddrive, when I run with the Ubuntu Studio 15.10 
(Wily Werewolf) Daily Build, it just crashed the kernel, this crash didn't 
happen of my last visit ubuntu14.10

http://cdimages.ubuntu.com/ubuntustudio/dvd/current/ (current is
28-Jun-2015 as the time now)

then I can reproduce this within VM, with Ubuntu 15.10 daily build
(current is 09-Jun-2015), from serial console I run strace \rm -rvf
/root and see kernel panic messages:

root@ubuntu-studio:~# cd /
root@ubuntu-studio:/# strace \rm -rvf /root && echo true
execve("/bin/rm", ["rm", "-rvf", "/root"], [/* 19 vars */]) = 0
brk(0)                                  = 0x2090000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 
0x7f91151e4000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=123268, ...}) = 0
mmap(NULL, 123268, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f91151c5000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0`\v\2\0\0\0\0\0"..., 
832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1869392, ...}) = 0
mmap(NULL, 3972864, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 
0x7f9114bf9000
mprotect(0x7f9114db9000, 2097152, PROT_NONE) = 0
mmap(0x7f9114fb9000, 24576, PROT_READ|PROT_WRITE, 
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1c0000) = 0x7f9114fb9000
mmap(0x7f9114fbf000, 16128, PROT_READ|PROT_WRITE, 
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f9114fbf000
close(3)                                = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 
0x7f91151c4000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 
0x7f91151c3000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 
0x7f91151c2000
arch_prctl(ARCH_SET_FS, 0x7f91151c3700) = 0
mprotect(0x7f9114fb9000, 16384, PROT_READ) = 0
mprotect(0x60d000, 4096, PROT_READ)     = 0
mprotect(0x7f91151e6000, 4096, PROT_READ) = 0
munmap(0x7f91151c5000, 123268)          = 0
brk(0)                                  = 0x2090000
brk(0x20b1000)                          = 0x20b1000
open("/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=2919792, ...}) = 0
mmap(NULL, 2919792, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f9114930000
close(3)                                = 0
ioctl(0, SNDCTL_TMR_TIMEBASE or SNDRV_TIMER_IOCTL_NEXT_DEVICE or TCGETS, {B9600 
opost isig icanon echo ...}) = 0
lstat("/", {st_mode=S_IFDIR|0755, st_size=260, ...}) = 0
newfstatat(AT_FDCWD, "/root", {st_mode=S_IFDIR|0700, st_size=60, ...}, 
AT_SYMLINK_NOFOLLOW) = 0
openat(AT_FDCWD, "/root", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_DIRECTORY|O_NOFOLLOW) 
= 3
fstat(3, {st_mode=S_IFDIR|0700, st_size=60, ...}) = 0
fcntl(3, F_GETFL)                       = 0x38800 (flags 
O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_NOFOLLOW)
fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
getdents(3, /* 5 entries */, 32768)     = 144
close(3)                                = 0
openat(AT_FDCWD, "/root", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_DIRECTORY|O_NOFOLLOW) 
= 3
fcntl(3, F_GETFD)                       = 0
fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
fstat(3, {st_mode=S_IFDIR|0700, st_size=60, ...}) = 0
fcntl(3, F_GETFL)                       = 0x38800 (flags 
O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_NOFOLLOW)
fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
fcntl(3, F_DUPFD, 3)                    = 4
fcntl(4, F_GETFD)                       = 0
fcntl(4, F_SETFD, FD_CLOEXEC)           = 0
getdents(3, /* 5 entries */, 32768)     = 144
getdents(3, /* 0 entries */, 32768)     = 0
close(3)                                = 0
unlinkat(4, ".bashrc", 0)               = 0
open("/usr/share/locale/locale.alias", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=2570, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 
0x7f91151e3000
read(3, "# Locale name alias data base.\n#"..., 1024) = 1024
read(3, " entries are case independent.\n\n"..., 1024) = 1024
read(3, "R\nko_KR\t\tko_KR.eucKR\nlithuanian "..., 1024) = 522
read(3, "", 1024)                       = 0
close(3)                                = 0
munmap(0x7f91151e3000, 4096)            = 0
open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 
ENOENT (No such file or directory)
open("/usr/share/locale/en_US.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 
ENOENT (No such file or directory)
open("/usr/share/locale/en_US/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT 
(No such file or directory)
open("/usr/share/locale/en.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 
ENOENT (No such file or directory)
open("/usr/share/locale/en.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 
ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No 
such file or directory)
open("/usr/share/locale-langpack/en_US.UTF-8/LC_MESSAGES/coreutils.mo", 
O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en_US.utf8/LC_MESSAGES/coreutils.mo", 
O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en_US/LC_MESSAGES/coreutils.mo", O_RDONLY) = 
-1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) 
= -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = 
-1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en/LC_MESSAGES/coreutils.mo", O_RDONLY) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=619, ...}) = 0
mmap(NULL, 619, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f91151e3000
close(3)                                = 0
open("/usr/lib/charset.alias", O_RDONLY|O_NOFOLLOW) = -1 ENOENT (No such file 
or directory)
fstat(1, {st_mode=S_IFCHR|0600, st_rdev=makedev(4, 64), ...}) = 0
ioctl(1, SNDCTL_TMR_TIMEBASE or SNDRV_TIMER_IOCTL_NEXT_DEVICE or TCGETS, {B9600 
opost isig icanon echo ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 
0x7f91151e2000
write(1, "removed \342\200\230/root/.bashrc\342\200\231\n", 28removed 
‘/root/.bashrc’
) = 28
unlinkat(4, ".profile", 0)              = 0
write(1, "removed \342\200\230/root/.profile\342\200\231\n", 29removed 
‘/root/.profile’
) = 29
newfstatat(4, ".cache", {st_mode=S_IFDIR|0700, st_size=60, ...}, 
AT_SYMLINK_NOFOLLOW) = 0
openat(4, ".cache", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_DIRECTORY|O_NOFOLLOW) = 3
fstat(3, {st_mode=S_IFDIR|0700, st_size=60, ...}) = 0
fcntl(3, F_GETFL)                       = 0x38800 (flags 
O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_NOFOLLOW)
fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
getdents(3, /* 3 entries */, 32768)     = 88
close(3)                                = 0
openat(4, ".cache", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_DIRECTORY|O_NOFOLLOW) = 3
fcntl(3, F_GETFD)                       = 0
fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
fstat(3, {st_mode=S_IFDIR|0700, st_size=60, ...}) = 0
fcntl(3, F_GETFL)                       = 0x38800 (flags 
O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_NOFOLLOW)
fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
fcntl(3, F_DUPFD, 3)                    = 5
fcntl(5, F_GETFD)                       = 0
fcntl(5, F_SETFD, FD_CLOEXEC)           = 0
getdents(3, /* 3 entries */, 32768)     = 88
getdents(3, /* 0 entries */, 32768)     = 0
close(3)                                = 0
unlinkat(5, "motd.legal-displayed", 0)  = 0
write(1, "removed \342\200\230/root/.cache/motd.leg"..., 48removed 
‘/root/.cache/motd.legal-displayed’
) = 48
close(5)                                = 0
unlinkat(4, ".cache", AT_REMOVEDIR)     = 0
write(1, "removed directory: \342\200\230/root/.cac"..., 38removed directory: 
‘/root/.cache’
) = 38
close(4)                                = 0
unlinkat(AT_FDCWD, "/root", AT_REMOVEDIR[   77.975408] BUG: unable to handle 
kernel NULL pointer dereference at 0000000000000016
[   77.976006] IP: [<ffffffff81219ba0>] __detach_mounts+0x40/0x90
[   77.976006] PGD 127fa067 PUD 112cd067 PMD 0 
[   77.976006] Oops: 0000 [#1] PREEMPT SMP 
[   77.976006] Modules linked in: kvm_intel kvm crct10dif_pclmul crc32_pclmul 
ghash_clmulni_intel aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper 
cryptd dm_multipath scsi_dh serio_raw i2c_piix4 cfg80211 8250_fintek mac_hid 
cuse parport_pc ppdev lp parport autofs4 squashfs overlay nls_utf8 isofs 
dm_mirror dm_region_hash dm_log psmouse e1000 pata_acpi floppy
[   77.976006] CPU: 0 PID: 2308 Comm: rm Not tainted 3.19.0-22-lowlatency 
#22-Ubuntu
[   77.976006] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
1.8.1-20150604_211837-tipua 04/01/2014
[   77.976006] task: ffff880006db09f0 ti: ffff880011310000 task.ti: 
ffff880011310000
[   77.976006] RIP: 0010:[<ffffffff81219ba0>]  [<ffffffff81219ba0>] 
__detach_mounts+0x40/0x90
[   77.976006] RSP: 0018:ffff880011313e38  EFLAGS: 00010206
[   77.976006] RAX: 0000000026842684 RBX: fffffffffffffffe RCX: 000000000000000c
[   77.976006] RDX: 0000000000002684 RSI: ffffffffffffffff RDI: ffffffff81c0c4c4
[   77.976006] RBP: ffff880011313e48 R08: 0000000000000000 R09: 0000000000000246
[   77.976006] R10: ffffffff81198297 R11: ffff8800051d4c00 R12: ffff88003305f718
[   77.976006] R13: ffff880053323cd8 R14: 00000000ffffff9c R15: 0000000000000000
[   77.976006] FS:  00007f91151c3700(0000) GS:ffff880055e00000(0000) 
knlGS:0000000000000000
[   77.976006] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   77.976006] CR2: 0000000000000016 CR3: 000000001240f000 CR4: 00000000001407f0
[   77.976006] Stack:
[   77.976006]  ffff880011313e48 ffff88003305f6c0 ffff880011313e78 
ffffffff81202a7f
[   77.976006]  ffff880011313e68 ffff88001f427000 0000000000000000 
00000000020910c0
[   77.976006]  ffff880011313f68 ffffffff812083f3 ffff88003305f6c0 
ffff880011313ea8
[   77.976006] Call Trace:
[   77.976006]  [<ffffffff81202a7f>] vfs_rmdir+0x12f/0x140
[   77.976006]  [<ffffffff812083f3>] do_rmdir+0x203/0x220
[   77.976006]  [<ffffffff810257f7>] ? syscall_trace_enter_phase2+0x107/0x240
[   77.976006]  [<ffffffff81025a23>] ? syscall_trace_leave+0x83/0x170
[   77.976006]  [<ffffffff812097f5>] SyS_unlinkat+0x25/0x40
[   77.976006]  [<ffffffff817cf984>] tracesys_phase2+0xd8/0xdd
[   77.976006] Code: 83 ec 08 e8 93 3b 5b 00 48 89 df e8 eb d2 ff ff 48 85 c0 
48 89 c3 74 55 48 c7 c7 c4 c4 c0 81 e8 77 58 5b 00 83 05 20 29 9f 00 01 <48> 8b 
53 18 48 85 d2 74 1e 0f 1f 80 00 00 00 00 48 8d ba 10 ff 
[   77.976006] RIP  [<ffffffff81219ba0>] __detach_mounts+0x40/0x90
[   77.976006]  RSP <ffff880011313e38>
[   77.976006] CR2: 0000000000000016
[   77.976006] ---[ end trace ba33e07ed00b256d ]---
[   77.976006] note: rm[2308] exited with preempt_count 1

telnet> send brk                 # here I tried to send a break for
SysRq, but the kernel is not responding at the moment,

[  104.042006] NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [rm:2308]
[  104.042006] Modules linked in: kvm_intel kvm crct10dif_pclmul crc32_pclmul 
ghash_clmulni_intel aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper 
cryptd dm_multipath scsi_dh serio_raw i2c_piix4 cfg80211 8250_fintek mac_hid 
cuse parport_pc ppdev lp parport autofs4 squashfs overlay nls_utf8 isofs 
dm_mirror dm_region_hash dm_log psmouse e1000 pata_acpi floppy
[  104.042006] CPU: 0 PID: 2308 Comm: rm Tainted: G      D        
3.19.0-22-lowlatency #22-Ubuntu
[  104.042006] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
1.8.1-20150604_211837-tipua 04/01/2014
[  104.042006] task: ffff880006db09f0 ti: ffff880011310000 task.ti: 
ffff880011310000
[  104.042006] RIP: 0010:[<ffffffff8105d156>]  [<ffffffff8105d156>] 
native_safe_halt+0x6/0x10
[  104.042006] RSP: 0018:ffff880011313910  EFLAGS: 00000206
[  104.042006] RAX: 0000000000002685 RBX: 0100000000000000 RCX: 0000000000075898
[  104.042006] RDX: 0000000000000000 RSI: 0000000000000002 RDI: ffff8800560ed000
[  104.042006] RBP: ffff880011313910 R08: 0000000000000004 R09: 0000000000000246
[  104.042006] R10: ffffffff8119f621 R11: 0000000000000000 R12: ffff8800560f1780
[  104.042006] R13: ffffea000044b3c0 R14: ffffffff811d7255 R15: ffff880011313918
[  104.042006] FS:  0000000000000000(0000) GS:ffff880055e00000(0000) 
knlGS:0000000000000000
[  104.042006] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  104.042006] CR2: 0000000000000016 CR3: 0000000001c13000 CR4: 00000000001407f0
[  104.042006] Stack:
[  104.042006]  ffff880011313960 ffffffff8105cb8c ffffffff811d76d6 
00002686113139b8
[  104.042006]  ffff8800051d0a80 ffff88004f5c7280 0000000040000010 
ffff8800127c6a98
[  104.042006]  ffff8800051a5a80 ffff88004f5c72a0 ffff8800113139b8 
ffffffff8105be51
[  104.042006] Call Trace:
[  104.042006]  [<ffffffff8105cb8c>] kvm_lock_spinning+0xbc/0x220
[  104.042006]  [<ffffffff811d76d6>] ? kmem_cache_free+0x206/0x240
[  104.042006]  [<ffffffff8105be51>] 
__raw_callee_save_kvm_lock_spinning+0x11/0x20
[  104.042006]  [<ffffffff8119f621>] ? kzfree+0x31/0x40
[  104.042006]  [<ffffffff817cf48b>] ? _raw_spin_lock+0x7b/0x80
[  104.042006]  [<ffffffff81218694>] mntput_no_expire+0x44/0x160
[  104.042006]  [<ffffffff812187d4>] mntput+0x24/0x40
[  104.042006]  [<ffffffff811f8a72>] __fput+0x182/0x240
[  104.042006]  [<ffffffff811f8b7e>] ____fput+0xe/0x10
[  104.042006]  [<ffffffff81094317>] task_work_run+0xb7/0xf0
[  104.042006]  [<ffffffff81079c5d>] do_exit+0x35d/0xa70
[  104.042006]  [<ffffffff810ce625>] ? kmsg_dump+0xc5/0xd0
[  104.042006]  [<ffffffff81019ba8>] oops_end+0xa8/0x120
[  104.042006]  [<ffffffff81063b2d>] no_context+0x11d/0x390
[  104.042006]  [<ffffffff81211149>] ? __d_alloc+0x29/0x190
[  104.042006]  [<ffffffff8108022d>] ? ns_capable+0x2d/0x60
[  104.042006]  [<ffffffff81063e1d>] __bad_area_nosemaphore+0x7d/0x210
[  104.042006]  [<ffffffff81211149>] ? __d_alloc+0x29/0x190
[  104.042006]  [<ffffffff81063fc3>] bad_area_nosemaphore+0x13/0x20
[  104.042006]  [<ffffffff810642be>] __do_page_fault+0xbe/0x5e0
[  104.042006]  [<ffffffff810da87d>] ? call_rcu+0x1d/0x20
[  104.042006]  [<ffffffff811940e1>] ? shmem_destroy_inode+0x31/0x50
[  104.042006]  [<ffffffff81064895>] trace_do_page_fault+0x45/0x140
[  104.042006]  [<ffffffff8105c4de>] do_async_page_fault+0x1e/0xd0
[  104.042006]  [<ffffffff817d1948>] async_page_fault+0x28/0x30
[  104.042006]  [<ffffffff81198297>] ? shmem_evict_inode+0x57/0x140
[  104.042006]  [<ffffffff81219ba0>] ? __detach_mounts+0x40/0x90
[  104.042006]  [<ffffffff81219b99>] ? __detach_mounts+0x39/0x90
[  104.042006]  [<ffffffff81202a7f>] vfs_rmdir+0x12f/0x140
[  104.042006]  [<ffffffff812083f3>] do_rmdir+0x203/0x220
[  104.042006]  [<ffffffff810257f7>] ? syscall_trace_enter_phase2+0x107/0x240
[  104.042006]  [<ffffffff81025a23>] ? syscall_trace_leave+0x83/0x170
[  104.042006]  [<ffffffff812097f5>] SyS_unlinkat+0x25/0x40
[  104.042006]  [<ffffffff817cf984>] tracesys_phase2+0xd8/0xdd
[  104.042006] Code: 00 00 00 00 00 55 48 89 e5 fa 5d c3 66 0f 1f 84 00 00 00 
00 00 55 48 89 e5 fb 5d c3 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 fb f4 <5d> c3 
0f 1f 84 00 00 00 00 00 55 48 89 e5 f4 5d c3 66 0f 1f 84 
QEMU 2.3.0 monitor - type 'help' for more information
(qemu) quit
Connection closed by foreign host.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: linux-image-3.19.0-22-lowlatency 3.19.0-22.22
ProcVersionSignature: Ubuntu 3.19.0-22.22-lowlatency 3.19.8-ckt1
Uname: Linux 3.19.0-22-lowlatency x86_64
NonfreeKernelModules: wl
ApportVersion: 2.17.3-0ubuntu4
Architecture: amd64
CasperVersion: 1.361
CurrentDesktop: XFCE
Date: Sun Jun 28 18:38:29 2015
LiveMediaBuild: Ubuntu-Studio 15.10 "Wily Werewolf" - Alpha amd64 (20150623)
MachineType: Apple Inc. MacBookPro11,2
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/studio/casper/vmlinuz 
file=/cdrom/preseed/ubuntustudio.seed boot=casper 
iso-scan/filename=/studio/wily-dvd-amd64.iso quiet splash username=username 
acpi_osi=Linux acpi=force acpi_enforce_resources=lax i915.enable_rc6=1 
i915.enable_fbc=1 i915.lvds_downclock=1 i915.semaphores=1 pcie_aspm=force 
crashkernel=auto ---
RelatedPackageVersions:
 linux-restricted-modules-3.19.0-22-lowlatency N/A
 linux-backports-modules-3.19.0-22-lowlatency  N/A
 linux-firmware                                1.144
SourcePackage: linux
StagingDrivers: r8188eu
UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 01/07/2015
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MBP112.88Z.0138.B14.1501071031
dmi.board.asset.tag: Base Board Asset Tag#
dmi.board.name: Mac-3CBD00234E554E41
dmi.board.vendor: Apple Inc.
dmi.board.version: MacBookPro11,2
dmi.chassis.type: 10
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-3CBD00234E554E41
dmi.modalias: 
dmi:bvnAppleInc.:bvrMBP112.88Z.0138.B14.1501071031:bd01/07/2015:svnAppleInc.:pnMacBookPro11,2:pvr1.0:rvnAppleInc.:rnMac-3CBD00234E554E41:rvrMacBookPro11,2:cvnAppleInc.:ct10:cvrMac-3CBD00234E554E41:
dmi.product.name: MacBookPro11,2
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug staging wily

-- 
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https://bugs.launchpad.net/bugs/1469579

Title:
  kernel crash when doing `rm -rf /root`

Status in linux package in Ubuntu:
  New

Bug description:
  
  to make a persistent /root, I'd usually like to rm -rf /root and make it a 
symlink to somewhere on the harddrive, when I run with the Ubuntu Studio 15.10 
(Wily Werewolf) Daily Build, it just crashed the kernel, this crash didn't 
happen of my last visit ubuntu14.10

  http://cdimages.ubuntu.com/ubuntustudio/dvd/current/ (current is
  28-Jun-2015 as the time now)

  then I can reproduce this within VM, with Ubuntu 15.10 daily build
  (current is 09-Jun-2015), from serial console I run strace \rm -rvf
  /root and see kernel panic messages:

  root@ubuntu-studio:~# cd /
  root@ubuntu-studio:/# strace \rm -rvf /root && echo true
  execve("/bin/rm", ["rm", "-rvf", "/root"], [/* 19 vars */]) = 0
  brk(0)                                  = 0x2090000
  access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or 
directory)
  mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 
0x7f91151e4000
  access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or 
directory)
  open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
  fstat(3, {st_mode=S_IFREG|0644, st_size=123268, ...}) = 0
  mmap(NULL, 123268, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f91151c5000
  close(3)                                = 0
  access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or 
directory)
  open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
  read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0`\v\2\0\0\0\0\0"..., 
832) = 832
  fstat(3, {st_mode=S_IFREG|0755, st_size=1869392, ...}) = 0
  mmap(NULL, 3972864, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 
0x7f9114bf9000
  mprotect(0x7f9114db9000, 2097152, PROT_NONE) = 0
  mmap(0x7f9114fb9000, 24576, PROT_READ|PROT_WRITE, 
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1c0000) = 0x7f9114fb9000
  mmap(0x7f9114fbf000, 16128, PROT_READ|PROT_WRITE, 
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f9114fbf000
  close(3)                                = 0
  mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 
0x7f91151c4000
  mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 
0x7f91151c3000
  mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 
0x7f91151c2000
  arch_prctl(ARCH_SET_FS, 0x7f91151c3700) = 0
  mprotect(0x7f9114fb9000, 16384, PROT_READ) = 0
  mprotect(0x60d000, 4096, PROT_READ)     = 0
  mprotect(0x7f91151e6000, 4096, PROT_READ) = 0
  munmap(0x7f91151c5000, 123268)          = 0
  brk(0)                                  = 0x2090000
  brk(0x20b1000)                          = 0x20b1000
  open("/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 3
  fstat(3, {st_mode=S_IFREG|0644, st_size=2919792, ...}) = 0
  mmap(NULL, 2919792, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f9114930000
  close(3)                                = 0
  ioctl(0, SNDCTL_TMR_TIMEBASE or SNDRV_TIMER_IOCTL_NEXT_DEVICE or TCGETS, 
{B9600 opost isig icanon echo ...}) = 0
  lstat("/", {st_mode=S_IFDIR|0755, st_size=260, ...}) = 0
  newfstatat(AT_FDCWD, "/root", {st_mode=S_IFDIR|0700, st_size=60, ...}, 
AT_SYMLINK_NOFOLLOW) = 0
  openat(AT_FDCWD, "/root", 
O_RDONLY|O_NOCTTY|O_NONBLOCK|O_DIRECTORY|O_NOFOLLOW) = 3
  fstat(3, {st_mode=S_IFDIR|0700, st_size=60, ...}) = 0
  fcntl(3, F_GETFL)                       = 0x38800 (flags 
O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_NOFOLLOW)
  fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
  getdents(3, /* 5 entries */, 32768)     = 144
  close(3)                                = 0
  openat(AT_FDCWD, "/root", 
O_RDONLY|O_NOCTTY|O_NONBLOCK|O_DIRECTORY|O_NOFOLLOW) = 3
  fcntl(3, F_GETFD)                       = 0
  fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
  fstat(3, {st_mode=S_IFDIR|0700, st_size=60, ...}) = 0
  fcntl(3, F_GETFL)                       = 0x38800 (flags 
O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_NOFOLLOW)
  fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
  fcntl(3, F_DUPFD, 3)                    = 4
  fcntl(4, F_GETFD)                       = 0
  fcntl(4, F_SETFD, FD_CLOEXEC)           = 0
  getdents(3, /* 5 entries */, 32768)     = 144
  getdents(3, /* 0 entries */, 32768)     = 0
  close(3)                                = 0
  unlinkat(4, ".bashrc", 0)               = 0
  open("/usr/share/locale/locale.alias", O_RDONLY|O_CLOEXEC) = 3
  fstat(3, {st_mode=S_IFREG|0644, st_size=2570, ...}) = 0
  mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 
0x7f91151e3000
  read(3, "# Locale name alias data base.\n#"..., 1024) = 1024
  read(3, " entries are case independent.\n\n"..., 1024) = 1024
  read(3, "R\nko_KR\t\tko_KR.eucKR\nlithuanian "..., 1024) = 522
  read(3, "", 1024)                       = 0
  close(3)                                = 0
  munmap(0x7f91151e3000, 4096)            = 0
  open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 
ENOENT (No such file or directory)
  open("/usr/share/locale/en_US.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 
ENOENT (No such file or directory)
  open("/usr/share/locale/en_US/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 
ENOENT (No such file or directory)
  open("/usr/share/locale/en.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 
ENOENT (No such file or directory)
  open("/usr/share/locale/en.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 
ENOENT (No such file or directory)
  open("/usr/share/locale/en/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT 
(No such file or directory)
  open("/usr/share/locale-langpack/en_US.UTF-8/LC_MESSAGES/coreutils.mo", 
O_RDONLY) = -1 ENOENT (No such file or directory)
  open("/usr/share/locale-langpack/en_US.utf8/LC_MESSAGES/coreutils.mo", 
O_RDONLY) = -1 ENOENT (No such file or directory)
  open("/usr/share/locale-langpack/en_US/LC_MESSAGES/coreutils.mo", O_RDONLY) = 
-1 ENOENT (No such file or directory)
  open("/usr/share/locale-langpack/en.UTF-8/LC_MESSAGES/coreutils.mo", 
O_RDONLY) = -1 ENOENT (No such file or directory)
  open("/usr/share/locale-langpack/en.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) 
= -1 ENOENT (No such file or directory)
  open("/usr/share/locale-langpack/en/LC_MESSAGES/coreutils.mo", O_RDONLY) = 3
  fstat(3, {st_mode=S_IFREG|0644, st_size=619, ...}) = 0
  mmap(NULL, 619, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f91151e3000
  close(3)                                = 0
  open("/usr/lib/charset.alias", O_RDONLY|O_NOFOLLOW) = -1 ENOENT (No such file 
or directory)
  fstat(1, {st_mode=S_IFCHR|0600, st_rdev=makedev(4, 64), ...}) = 0
  ioctl(1, SNDCTL_TMR_TIMEBASE or SNDRV_TIMER_IOCTL_NEXT_DEVICE or TCGETS, 
{B9600 opost isig icanon echo ...}) = 0
  mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 
0x7f91151e2000
  write(1, "removed \342\200\230/root/.bashrc\342\200\231\n", 28removed 
‘/root/.bashrc’
  ) = 28
  unlinkat(4, ".profile", 0)              = 0
  write(1, "removed \342\200\230/root/.profile\342\200\231\n", 29removed 
‘/root/.profile’
  ) = 29
  newfstatat(4, ".cache", {st_mode=S_IFDIR|0700, st_size=60, ...}, 
AT_SYMLINK_NOFOLLOW) = 0
  openat(4, ".cache", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_DIRECTORY|O_NOFOLLOW) = 3
  fstat(3, {st_mode=S_IFDIR|0700, st_size=60, ...}) = 0
  fcntl(3, F_GETFL)                       = 0x38800 (flags 
O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_NOFOLLOW)
  fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
  getdents(3, /* 3 entries */, 32768)     = 88
  close(3)                                = 0
  openat(4, ".cache", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_DIRECTORY|O_NOFOLLOW) = 3
  fcntl(3, F_GETFD)                       = 0
  fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
  fstat(3, {st_mode=S_IFDIR|0700, st_size=60, ...}) = 0
  fcntl(3, F_GETFL)                       = 0x38800 (flags 
O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_NOFOLLOW)
  fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
  fcntl(3, F_DUPFD, 3)                    = 5
  fcntl(5, F_GETFD)                       = 0
  fcntl(5, F_SETFD, FD_CLOEXEC)           = 0
  getdents(3, /* 3 entries */, 32768)     = 88
  getdents(3, /* 0 entries */, 32768)     = 0
  close(3)                                = 0
  unlinkat(5, "motd.legal-displayed", 0)  = 0
  write(1, "removed \342\200\230/root/.cache/motd.leg"..., 48removed 
‘/root/.cache/motd.legal-displayed’
  ) = 48
  close(5)                                = 0
  unlinkat(4, ".cache", AT_REMOVEDIR)     = 0
  write(1, "removed directory: \342\200\230/root/.cac"..., 38removed directory: 
‘/root/.cache’
  ) = 38
  close(4)                                = 0
  unlinkat(AT_FDCWD, "/root", AT_REMOVEDIR[   77.975408] BUG: unable to handle 
kernel NULL pointer dereference at 0000000000000016
  [   77.976006] IP: [<ffffffff81219ba0>] __detach_mounts+0x40/0x90
  [   77.976006] PGD 127fa067 PUD 112cd067 PMD 0 
  [   77.976006] Oops: 0000 [#1] PREEMPT SMP 
  [   77.976006] Modules linked in: kvm_intel kvm crct10dif_pclmul crc32_pclmul 
ghash_clmulni_intel aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper 
cryptd dm_multipath scsi_dh serio_raw i2c_piix4 cfg80211 8250_fintek mac_hid 
cuse parport_pc ppdev lp parport autofs4 squashfs overlay nls_utf8 isofs 
dm_mirror dm_region_hash dm_log psmouse e1000 pata_acpi floppy
  [   77.976006] CPU: 0 PID: 2308 Comm: rm Not tainted 3.19.0-22-lowlatency 
#22-Ubuntu
  [   77.976006] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
1.8.1-20150604_211837-tipua 04/01/2014
  [   77.976006] task: ffff880006db09f0 ti: ffff880011310000 task.ti: 
ffff880011310000
  [   77.976006] RIP: 0010:[<ffffffff81219ba0>]  [<ffffffff81219ba0>] 
__detach_mounts+0x40/0x90
  [   77.976006] RSP: 0018:ffff880011313e38  EFLAGS: 00010206
  [   77.976006] RAX: 0000000026842684 RBX: fffffffffffffffe RCX: 
000000000000000c
  [   77.976006] RDX: 0000000000002684 RSI: ffffffffffffffff RDI: 
ffffffff81c0c4c4
  [   77.976006] RBP: ffff880011313e48 R08: 0000000000000000 R09: 
0000000000000246
  [   77.976006] R10: ffffffff81198297 R11: ffff8800051d4c00 R12: 
ffff88003305f718
  [   77.976006] R13: ffff880053323cd8 R14: 00000000ffffff9c R15: 
0000000000000000
  [   77.976006] FS:  00007f91151c3700(0000) GS:ffff880055e00000(0000) 
knlGS:0000000000000000
  [   77.976006] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [   77.976006] CR2: 0000000000000016 CR3: 000000001240f000 CR4: 
00000000001407f0
  [   77.976006] Stack:
  [   77.976006]  ffff880011313e48 ffff88003305f6c0 ffff880011313e78 
ffffffff81202a7f
  [   77.976006]  ffff880011313e68 ffff88001f427000 0000000000000000 
00000000020910c0
  [   77.976006]  ffff880011313f68 ffffffff812083f3 ffff88003305f6c0 
ffff880011313ea8
  [   77.976006] Call Trace:
  [   77.976006]  [<ffffffff81202a7f>] vfs_rmdir+0x12f/0x140
  [   77.976006]  [<ffffffff812083f3>] do_rmdir+0x203/0x220
  [   77.976006]  [<ffffffff810257f7>] ? syscall_trace_enter_phase2+0x107/0x240
  [   77.976006]  [<ffffffff81025a23>] ? syscall_trace_leave+0x83/0x170
  [   77.976006]  [<ffffffff812097f5>] SyS_unlinkat+0x25/0x40
  [   77.976006]  [<ffffffff817cf984>] tracesys_phase2+0xd8/0xdd
  [   77.976006] Code: 83 ec 08 e8 93 3b 5b 00 48 89 df e8 eb d2 ff ff 48 85 c0 
48 89 c3 74 55 48 c7 c7 c4 c4 c0 81 e8 77 58 5b 00 83 05 20 29 9f 00 01 <48> 8b 
53 18 48 85 d2 74 1e 0f 1f 80 00 00 00 00 48 8d ba 10 ff 
  [   77.976006] RIP  [<ffffffff81219ba0>] __detach_mounts+0x40/0x90
  [   77.976006]  RSP <ffff880011313e38>
  [   77.976006] CR2: 0000000000000016
  [   77.976006] ---[ end trace ba33e07ed00b256d ]---
  [   77.976006] note: rm[2308] exited with preempt_count 1

  telnet> send brk                 # here I tried to send a break for
  SysRq, but the kernel is not responding at the moment,

  [  104.042006] NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [rm:2308]
  [  104.042006] Modules linked in: kvm_intel kvm crct10dif_pclmul crc32_pclmul 
ghash_clmulni_intel aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper 
cryptd dm_multipath scsi_dh serio_raw i2c_piix4 cfg80211 8250_fintek mac_hid 
cuse parport_pc ppdev lp parport autofs4 squashfs overlay nls_utf8 isofs 
dm_mirror dm_region_hash dm_log psmouse e1000 pata_acpi floppy
  [  104.042006] CPU: 0 PID: 2308 Comm: rm Tainted: G      D        
3.19.0-22-lowlatency #22-Ubuntu
  [  104.042006] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
1.8.1-20150604_211837-tipua 04/01/2014
  [  104.042006] task: ffff880006db09f0 ti: ffff880011310000 task.ti: 
ffff880011310000
  [  104.042006] RIP: 0010:[<ffffffff8105d156>]  [<ffffffff8105d156>] 
native_safe_halt+0x6/0x10
  [  104.042006] RSP: 0018:ffff880011313910  EFLAGS: 00000206
  [  104.042006] RAX: 0000000000002685 RBX: 0100000000000000 RCX: 
0000000000075898
  [  104.042006] RDX: 0000000000000000 RSI: 0000000000000002 RDI: 
ffff8800560ed000
  [  104.042006] RBP: ffff880011313910 R08: 0000000000000004 R09: 
0000000000000246
  [  104.042006] R10: ffffffff8119f621 R11: 0000000000000000 R12: 
ffff8800560f1780
  [  104.042006] R13: ffffea000044b3c0 R14: ffffffff811d7255 R15: 
ffff880011313918
  [  104.042006] FS:  0000000000000000(0000) GS:ffff880055e00000(0000) 
knlGS:0000000000000000
  [  104.042006] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [  104.042006] CR2: 0000000000000016 CR3: 0000000001c13000 CR4: 
00000000001407f0
  [  104.042006] Stack:
  [  104.042006]  ffff880011313960 ffffffff8105cb8c ffffffff811d76d6 
00002686113139b8
  [  104.042006]  ffff8800051d0a80 ffff88004f5c7280 0000000040000010 
ffff8800127c6a98
  [  104.042006]  ffff8800051a5a80 ffff88004f5c72a0 ffff8800113139b8 
ffffffff8105be51
  [  104.042006] Call Trace:
  [  104.042006]  [<ffffffff8105cb8c>] kvm_lock_spinning+0xbc/0x220
  [  104.042006]  [<ffffffff811d76d6>] ? kmem_cache_free+0x206/0x240
  [  104.042006]  [<ffffffff8105be51>] 
__raw_callee_save_kvm_lock_spinning+0x11/0x20
  [  104.042006]  [<ffffffff8119f621>] ? kzfree+0x31/0x40
  [  104.042006]  [<ffffffff817cf48b>] ? _raw_spin_lock+0x7b/0x80
  [  104.042006]  [<ffffffff81218694>] mntput_no_expire+0x44/0x160
  [  104.042006]  [<ffffffff812187d4>] mntput+0x24/0x40
  [  104.042006]  [<ffffffff811f8a72>] __fput+0x182/0x240
  [  104.042006]  [<ffffffff811f8b7e>] ____fput+0xe/0x10
  [  104.042006]  [<ffffffff81094317>] task_work_run+0xb7/0xf0
  [  104.042006]  [<ffffffff81079c5d>] do_exit+0x35d/0xa70
  [  104.042006]  [<ffffffff810ce625>] ? kmsg_dump+0xc5/0xd0
  [  104.042006]  [<ffffffff81019ba8>] oops_end+0xa8/0x120
  [  104.042006]  [<ffffffff81063b2d>] no_context+0x11d/0x390
  [  104.042006]  [<ffffffff81211149>] ? __d_alloc+0x29/0x190
  [  104.042006]  [<ffffffff8108022d>] ? ns_capable+0x2d/0x60
  [  104.042006]  [<ffffffff81063e1d>] __bad_area_nosemaphore+0x7d/0x210
  [  104.042006]  [<ffffffff81211149>] ? __d_alloc+0x29/0x190
  [  104.042006]  [<ffffffff81063fc3>] bad_area_nosemaphore+0x13/0x20
  [  104.042006]  [<ffffffff810642be>] __do_page_fault+0xbe/0x5e0
  [  104.042006]  [<ffffffff810da87d>] ? call_rcu+0x1d/0x20
  [  104.042006]  [<ffffffff811940e1>] ? shmem_destroy_inode+0x31/0x50
  [  104.042006]  [<ffffffff81064895>] trace_do_page_fault+0x45/0x140
  [  104.042006]  [<ffffffff8105c4de>] do_async_page_fault+0x1e/0xd0
  [  104.042006]  [<ffffffff817d1948>] async_page_fault+0x28/0x30
  [  104.042006]  [<ffffffff81198297>] ? shmem_evict_inode+0x57/0x140
  [  104.042006]  [<ffffffff81219ba0>] ? __detach_mounts+0x40/0x90
  [  104.042006]  [<ffffffff81219b99>] ? __detach_mounts+0x39/0x90
  [  104.042006]  [<ffffffff81202a7f>] vfs_rmdir+0x12f/0x140
  [  104.042006]  [<ffffffff812083f3>] do_rmdir+0x203/0x220
  [  104.042006]  [<ffffffff810257f7>] ? syscall_trace_enter_phase2+0x107/0x240
  [  104.042006]  [<ffffffff81025a23>] ? syscall_trace_leave+0x83/0x170
  [  104.042006]  [<ffffffff812097f5>] SyS_unlinkat+0x25/0x40
  [  104.042006]  [<ffffffff817cf984>] tracesys_phase2+0xd8/0xdd
  [  104.042006] Code: 00 00 00 00 00 55 48 89 e5 fa 5d c3 66 0f 1f 84 00 00 00 
00 00 55 48 89 e5 fb 5d c3 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 fb f4 <5d> c3 
0f 1f 84 00 00 00 00 00 55 48 89 e5 f4 5d c3 66 0f 1f 84 
  QEMU 2.3.0 monitor - type 'help' for more information
  (qemu) quit
  Connection closed by foreign host.

  ProblemType: Bug
  DistroRelease: Ubuntu 15.10
  Package: linux-image-3.19.0-22-lowlatency 3.19.0-22.22
  ProcVersionSignature: Ubuntu 3.19.0-22.22-lowlatency 3.19.8-ckt1
  Uname: Linux 3.19.0-22-lowlatency x86_64
  NonfreeKernelModules: wl
  ApportVersion: 2.17.3-0ubuntu4
  Architecture: amd64
  CasperVersion: 1.361
  CurrentDesktop: XFCE
  Date: Sun Jun 28 18:38:29 2015
  LiveMediaBuild: Ubuntu-Studio 15.10 "Wily Werewolf" - Alpha amd64 (20150623)
  MachineType: Apple Inc. MacBookPro11,2
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/studio/casper/vmlinuz 
file=/cdrom/preseed/ubuntustudio.seed boot=casper 
iso-scan/filename=/studio/wily-dvd-amd64.iso quiet splash username=username 
acpi_osi=Linux acpi=force acpi_enforce_resources=lax i915.enable_rc6=1 
i915.enable_fbc=1 i915.lvds_downclock=1 i915.semaphores=1 pcie_aspm=force 
crashkernel=auto ---
  RelatedPackageVersions:
   linux-restricted-modules-3.19.0-22-lowlatency N/A
   linux-backports-modules-3.19.0-22-lowlatency  N/A
   linux-firmware                                1.144
  SourcePackage: linux
  StagingDrivers: r8188eu
  UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 01/07/2015
  dmi.bios.vendor: Apple Inc.
  dmi.bios.version: MBP112.88Z.0138.B14.1501071031
  dmi.board.asset.tag: Base Board Asset Tag#
  dmi.board.name: Mac-3CBD00234E554E41
  dmi.board.vendor: Apple Inc.
  dmi.board.version: MacBookPro11,2
  dmi.chassis.type: 10
  dmi.chassis.vendor: Apple Inc.
  dmi.chassis.version: Mac-3CBD00234E554E41
  dmi.modalias: 
dmi:bvnAppleInc.:bvrMBP112.88Z.0138.B14.1501071031:bd01/07/2015:svnAppleInc.:pnMacBookPro11,2:pvr1.0:rvnAppleInc.:rnMac-3CBD00234E554E41:rvrMacBookPro11,2:cvnAppleInc.:ct10:cvrMac-3CBD00234E554E41:
  dmi.product.name: MacBookPro11,2
  dmi.product.version: 1.0
  dmi.sys.vendor: Apple Inc.

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