debugging frequent crashes/reboot with nexus 6p
after going through the logs we found this part:

fs_mgr: Running /system/bin/e2fsck on /dev/block/platform/soc.0/f9824900.sdhci/by-name/userdata
&lt;14&gt;[    6.585352] e2fsck: e2fsck 1.42.9 (28-Dec-2013)
&lt;14&gt;[    6.585352] 
&lt;14&gt;[    6.585390] e2fsck: ext2fs_open2: Bad magic number in super-block
&lt;14&gt;[    6.585390] 
&lt;14&gt;[    6.585402] e2fsck: /system/bin/e2fsck: Superblock invalid, trying backup blocks...
&lt;14&gt;[    6.585402] 
&lt;14&gt;[    6.585414] e2fsck: /system/bin/e2fsck: Bad magic number in super-block while trying to open /dev/block/platform/soc.0/f9824900.sdhci/by-name/userdata
&lt;14&gt;[    6.585414] 
&lt;14&gt;[    6.585424] e2fsck: 
&lt;14&gt;[    6.585424] 
&lt;14&gt;[    6.585434] e2fsck: The superblock could not be read or does not describe a correct ext2
&lt;14&gt;[    6.585434] 
&lt;14&gt;[    6.585445] e2fsck: filesystem.  If the device is valid and it really contains an ext2
&lt;14&gt;[    6.585445] 
&lt;14&gt;[    6.585455] e2fsck: filesystem (and not swap or ufs or something else), then the superblock
&lt;14&gt;[    6.585455] 
&lt;14&gt;[    6.585466] e2fsck: is corrupt, and you might try running e2fsck with an alternate superblock:
&lt;14&gt;[    6.585466] 
&lt;14&gt;[    6.585476] e2fsck:     e2fsck -b 8193 &lt;device&gt;
&lt;14&gt;[    6.585476] 
&lt;14&gt;[    6.585486] e2fsck: 
&lt;14&gt;[    6.585486] 
&lt;14&gt;[    6.585501] e2fsck: e2fsck terminated by exit(8)
&lt;14&gt;[    6.585501] 


which shows that the file system is corrupt.. i guess that's it