[Xperia Z2 Android Development] neonixxx:
Thanks for that response. I think you may be right about the ROM too. I was getting random reboots here and there on previous versions, but since updating to 5.5.5, the reboots seem more frequent.

[MENTION=4817632]varund7726[/MENTION] I've pulled logs for the last two random reboots and the same thing seems to have happened both times. It looks like the kernel panics and emergency remounts the system as read only and then restarts. No clue why though. I posted the first log in Myself5's thread asking him if he might understand any more than I do, but I'm not so sure his kernel is solely at fault since [MENTION=4474140]oulouloul[/MENTION] reported random reboots with the stock kernel.

[49520.200383] IRQ40 no longer affine to CPU1
[49520.289513] init: untracked pid 24830 exited with status 1
[49522.150752] tfa98xx-codec tfa98xx-codec.1: set format for codec dai failed
[49525.317555] init: untracked pid 24859 exited with status 1
[49528.682567] tfa98xx-codec tfa98xx-codec.1: set format for codec dai failed
[49530.328592] init: untracked pid 24871 exited with status 1
[49535.879880] init: untracked pid 24900 exited with status 1
[49540.909964] init: untracked pid 24906 exited with status 1
[49545.938563] init: untracked pid 24909 exited with status 1
[49546.463454] tfa98xx-codec tfa98xx-codec.1: set format for codec dai failed
[49550.966588] init: untracked pid 24949 exited with status 1
[49555.867839] init: untracked pid 24990 exited with status 1
[49558.060785] IRQ40 no longer affine to CPU2
[49559.194084] qup_i2c f9928000.i2c: QUP: I2C status flags :0x81343c8, irq:132
[49559.194264] qup_i2c f9928000.i2c: I2C slave addr:0x28 not connected
[49560.472587] init: untracked pid 25109 exited with status 1
[49564.040710] android.bg: page allocation failure: order:4, mode:0x40d0
[49564.096976] android.bg: page allocation failure: order:4, mode:0x40d0
[49565.855127] init: untracked pid 25139 exited with status 1
[49570.866753] init: untracked pid 25204 exited with status 1
[49572.623039] init: untracked pid 4699 exited with status 0
[49575.638866] init: untracked pid 25294 exited with status 1
[B][49576.202865] SysRq : Emergency Remount R/O
[49576.415395] IRQ40 no longer affine to CPU2
[49576.809521] Restarting system with command ''.
[49576.809624] Restarting Linux version 3.4.0-M5-Kernel-ge816654-00630-g91dd0e7 (silas@X8SIL) (gcc version 4.9.x-sabermod 20150716 (release) (GCC) ) #1 SMP PREEMPT Fri Jul 24 22:42:56 CEST 2015
[49576.809628]
[49576.809771] Going down for restart now
[49576.810706] Calling SCM to disable SPMI PMIC arbiter
[/B]
No errors detected

[20305.471796] IRQ40 no longer affine to CPU3
[20307.730393] init: untracked pid 1138 exited with status 1
[20312.743662] init: untracked pid 1141 exited with status 1
[20317.768001] init: untracked pid 1145 exited with status 1
[20317.882713] tfa98xx-codec tfa98xx-codec.1: set format for codec dai failed
[20322.179616] tfa98xx-codec tfa98xx-codec.1: set format for codec dai failed
[20322.797903] init: untracked pid 1157 exited with status 1
[20326.384986] qup_i2c f9928000.i2c: QUP: I2C status flags :0x81343c8, irq:132
[20326.385148] qup_i2c f9928000.i2c: I2C slave addr:0x28 not connected
[20327.854795] init: untracked pid 1238 exited with status 1
[20328.280318] leds rgb: rgbcommon_sync_state_store do nothing. same state
[20328.308548] leds rgb: rgbcommon_sync_state_store do nothing. same state
[20328.740546] IRQ40 no longer affine to CPU3
[20332.795399] init: untracked pid 1329 exited with status 1
[20337.060696] IRQ40 no longer affine to CPU3
[20337.203278] init: untracked pid 1374 exited with status 1
[20337.505903] init: untracked pid 4983 exited with status 0
[B][20340.977547] SysRq : Emergency Remount R/O
[20341.083377] IRQ40 no longer affine to CPU2
[20341.559379] Restarting system with command ''.
[20341.559471] Restarting Linux version 3.4.0-M5-Kernel-ge816654-00630-g91dd0e7 (silas@X8SIL) (gcc version 4.9.x-sabermod 20150716 (release) (GCC) ) #1 SMP PREEMPT Fri Jul 24 22:42:56 CEST 2015
[20341.559475]
[20341.559777] Going down for restart now
[20341.560582] Calling SCM to disable SPMI PMIC arbiter[/B]

No errors detected

I notice that after most of the random reboots, there either is "No SIM card", or no data connection, or some other radio issue. But I think these point us more to something that happens as a result of the random reboot rather than to the cause of the reboots themselves.