Hi, I am running lubuntu 14.04 with the latest Linaro kernel (git.linaro.org/kernel/linux-linaro-tracking) on arndale, I found once X is started ('xinit' is enough) , any one of the following operations will very easily cause kernel panic or hang, (1) Ctrl+Alt+F1 and Alt+F7 switch between graphic mode and text mode; (2) 'xinit' to start graphic mode, then 'exit' to quit graphic mode; (3) After login into Lunbuntu desktop, switch user account to login;

The kernel is compiled by using the 'exynos_defconfig' and 'exynos5250-arndale.dts'. Sometimes the kernel hang without any response, sometimes the kernel panic with messages below,

[ 72.675919] Unable to handle kernel paging request at virtual address 72643d5 [ 72.676016] pgd = e8bdc000 [ 72.676055] [72643d45] *pgd=00000000 [ 72.676111] Internal error: Oops: 5 [#1] PREEMPT SMP ARM [ 72.676181] Modules linked in: [ 72.676231] CPU: 0 PID: 3840 Comm: udev-acl.ck Not tainted 3.15.0-rc8-dirty 2 [ 72.682703] task: e93b0c00 ti: e88fe000 task.ti: e88fe000 [ 72.688091] PC is at strnlen+0xc/0x54 [ 72.691733] LR is at string.isra.4+0x2c/0xcc ... [<c01c63c0>] (strnlen) from [<c01c7f34>] (string.isra.4+0x2c/0xc) [ 73.296125] [<c01c7f34>] (string.isra.4) from [<c01c92e4>] (vsnprintf+0x180/) [ 73.303676] [<c01c92e4>] (vsnprintf) from [<c01c9570>] (sprintf+0x24/0x34) [ 73.310536] [<c01c9570>] (sprintf) from [<c025f9fc>] (uevent_show+0xcc/0x100) [ 73.317651] [<c025f9fc>] (uevent_show) from [<c026004c>] (dev_attr_show+0x20) [ 73.325204] [<c026004c>] (dev_attr_show) from [<c0114ed0>] (sysfs_kf_seq_sho) [ 73.333276] [<c0114ed0>] (sysfs_kf_seq_show) from [<c0113cb4>] (kernfs_seq_s) [ 73.341522] [<c0113cb4>] (kernfs_seq_show) from [<c00d9670>] (seq_read+0x1c0) [ 73.349160] [<c00d9670>] (seq_read) from [<c00bb204>] (vfs_read+0x9c/0x12c) [ 73.356103] [<c00bb204>] (vfs_read) from [<c00bb3d0>] (SyS_read+0x44/0x84) [ 73.362961] [<c00bb3d0>] (SyS_read) from [<c000e420>] (ret_fast_syscall+0x0/) [ 73.370423] Code: e12fff1e e3510000 01a00001 012fff1e (e5d02000)

or sometimes with below,

[ 55.480788] Unable to handle kernel NULL pointer dereference ac [ 55.480896] pgd = e9b84000 [ 55.480935] [0000026c] *pgd=00000000 [ 55.480991] Internal error: Oops: 5 [#1] PREEMPT SMP ARM [ 55.481061] Modules linked in: [ 55.481155] CPU: 1 PID: 3488 Comm: Xorg Not tainted 3.15.0-rc8-dirty #12 [ 55.487835] task: ea1aa400 ti: e8f54000 task.ti: e8f54000 [ 55.493222] PC is at evdev_poll+0x28/0x64 [ 55.497218] LR is at do_select+0x328/0x650 [ 55.501291] pc : [<c02eb088>] lr : [<c00cb2dc>] psr: 600f0013 [ 55.501291] sp : e8f55b30 ip : e9bc4900 fp : c02eb060 [ 55.512747] r10: e9bc4900 r9 : 00000000 r8 : 00003c00 [ 55.517955] r7 : 0000000e r6 : 00000016 r5 : 00000000 r4 : e9355000 [ 55.524465] r3 : 00000000 r2 : e8f55bb4 r1 : 00000028 r0 : e9bc4900 [ 55.530976] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user [ 55.538093] Control: 10c5387d Table: 69b8406a DAC: 00000015 ... [<c02eb088>] (evdev_poll) from [<c00cb2dc>] (do_select+0x328/0x6) [ 56.505313] [<c00cb2dc>] (do_select) from [<c00cb754>] (core_sys_select+0x15) [ 56.513037] [<c00cb754>] (core_sys_select) from [<c00cb9d4>] (SyS_select+0xc) [ 56.520764] [<c00cb9d4>] (SyS_select) from [<c000e420>] (ret_fast_syscall+0x) [ 56.528397] Code: e2851028 e3530000 13750028 1a00000c (e5d5326c) [ 56.534547] ---[ end trace 6b03dd550054bcfd ]---

Any suggestion on how to fix this is appreciated.

Cheers,