After upgrade from Kubuntu 15.04 to Kubuntu 15.10 X Server starting to crash every few days

[RussianNeuroMancer]

After upgrade from Kubuntu 15.04 to Kubuntu 15.10 X Server starting to crash every few days. Sometimes crash may happen few times per day. This crash is reproducible with packages from main repository and from Xorg Edgers PPA. Attached logs is crated with Xorg Edgers PPA.

Please look into attached xorgcrash file. Other relevant logs is Xorglog2 and gdb-Xorg2.txt.
If this matter, Xorg also crash on login if I trying to start with glamor or modesetting driver (but I doesn't sure it's a same crash). I didn't tried modesetting driver in Kubuntu 15.04, but glamor works for sure (with some issues, but at least it doesn't crash on login). Currently radeon driver is used (GPU is Radeon HD 6620G).

[RussianNeuroMancer (russianneuromancer)]

I tried to attach additional logs using apport-collect, but unable to do this probably due to bug 1439784.

Please let me know which logs you need.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[RussianNeuroMancer (russianneuromancer)]

I get same crash with Intel GPU (ironlake generation) on another laptop, but with fglrx this crash seems like not reproducible (with same Radeon HD 6620G).

[Gannet (ken20001)]

The same is with Radeon HD2600 on wily. Xorg log is attached.