Just visiting some URLs will crash X and bring down the whole system without warning. Reproducible example: visit http://ello.co/jondcook in Chromium and the GPU will crash.
Ubuntu 12.04.5 LTS
[75195.004056] [drm] stuck on render ring
[75195.004067] [drm] GPU crash dump saved to /sys/class/drm/card0/error
[75195.004071] [drm] GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace.
[75195.004075] [drm] Please file a _new_ bug report on bugs.freedesktop.org against DRI -> DRM/Intel
[75195.004078] [drm] drm/i915 developers can then reassign to the right component if it's not a kernel issue.
[75195.004082] [drm] The gpu crash dump is required to analyze gpu hangs, so please always attach it.
[75195.005398] [drm:i915_set_reset_status] *ERROR* render ring hung inside bo (0x2088000 ctx 0) at 0x2089954
[75195.512106] [drm:i915_reset] *ERROR* Failed to reset chip.
[75200.348321] Watchdog[5421]: segfault at 0 ip aff4a4c8 sp ad0c4cf0 error 6 in libcontent.so[af72f000+11ee000]
[75205.036042] [drm:i915_gem_wait_for_error] *ERROR* Timed out waiting for the gpu reset to complete
[75205.092053] [drm] GMBUS [i915 gmbus vga] timed out, falling back to bit banging on pin 2
[75205.119530] ------------[ cut here ]------------
[75205.119593] WARNING: CPU: 0 PID: 1931 at /build/buildd/linux-lts-trusty-3.13.0/drivers/gpu/drm/i915/intel_display.c:922 assert_pll+0x7a/0x80 [i915]()
[75205.119597] PLL state assertion failure (expected on, current off)
[75205.119600] Modules linked in: usb_storage nls_iso8859_1 serpent_sse2_i586 ablk_helper cryptd glue_helper lrw serpent_generic twofish_generic twofish_i586 twofish_common xts gf128mul hidp hid nvram pci_stub vboxpci(OX) vboxnetadp(OX) vboxnetflt(OX) vboxdrv(OX) ctr ccm vsock zram(C) bnep rfcomm parport_pc ppdev binfmt_misc dm_crypt joydev xt_hl ip6t_rt nf_conntrack_ipv6 nf_defrag_ipv6 btusb bluetooth ipt_REJECT xt_LOG xt_multiport xt_limit xt_tcpudp xt_addrtype nf_conntrack_ipv4 nf_defrag_ipv4 xt_state ip6table_filter ip6_tables nf_conntrack_netbios_ns nf_conntrack_broadcast nf_nat_ftp nf_nat nf_conntrack_ftp nf_conntrack iptable_filter snd_hda_codec_si3054 snd_hda_codec_realtek ip_tables x_tables snd_hda_intel hp_wmi snd_hda_codec sparse_keymap snd_hwdep arc4 snd_pcm r852 snd_seq_midi snd_rawmidi snd_seq_midi_event iwl3945 sm_common nand iwlegacy mtd snd_seq nand_ids nand_bch snd_timer bch r592 mac80211 nand_ecc psmouse memstick lpc_ich serio_raw snd_seq_device cfg80211 snd soundcore snd_page_alloc mac_hid coretemp lp parport i915 firewire_ohci drm_kms_helper firewire_core drm ahci crc_itu_t libahci i2c_algo_bit r8169 sdhci_pci sdhci mii video wmi
[75205.119720] CPU: 0 PID: 1931 Comm: upowerd Tainted: G C OX 3.13.0-39-generic #66~precise1-Ubuntu
[75205.119724] Hardware name: Hewlett-Packard Presario V6500 Notebook PC /30CC, BIOS F.5A 03/22/2010
[75205.119727] 00000000 00000000 ee449c50 c1683110 f89adb0c ee449c80 c1059c54 f89afb04
[75205.119737] ee449cac 0000078b f89adb0c 0000039a f895e0fa f895e0fa 00000001 00000001
[75205.119746] 00000001 ee449c98 c1059d13 00000009 ee449c90 f89afb04 ee449cac ee449cbc
[75205.119755] Call Trace:
[75205.119766] [<c1683110>] dump_stack+0x41/0x52
[75205.119776] [<c1059c54>] warn_slowpath_common+0x84/0xa0
[75205.119813] [<f895e0fa>] ? assert_pll+0x7a/0x80 [i915]
[75205.119847] [<f895e0fa>] ? assert_pll+0x7a/0x80 [i915]
[75205.119852] [<c1059d13>] warn_slowpath_fmt+0x33/0x40
[75205.119887] [<f895e0fa>] assert_pll+0x7a/0x80 [i915]
[75205.119928] [<f8962104>] intel_crtc_load_lut+0x194/0x1a0 [i915]
[75205.119961] [<f895f37c>] ? i9xx_enable_pll+0x11c/0x190 [i915]
[75205.119994] [<f89621b8>] i9xx_crtc_enable+0xa8/0x150 [i915]
[75205.120059] [<f8963594>] __intel_set_mode+0x244/0x2f0 [i915]
[75205.120106] [<f8965ae3>] ? intel_framebuffer_create_for_mode.constprop.57+0xa3/0xb0 [i915]
[75205.120150] [<f8964ec7>] intel_set_mode+0x27/0x40 [i915]
[75205.120189] [<f8965d0d>] intel_get_load_detect_pipe+0x21d/0x300 [i915]
[75205.120237] [<f898b195>] intel_tv_detect+0x125/0x230 [i915]
[75205.120252] [<c1312101>] ? lockref_get_not_dead+0x11/0x40
[75205.120280] [<f880cbed>] status_show+0x3d/0x80 [drm]
[75205.120286] [<c116fcb4>] ? __kmalloc+0xa4/0x210
[75205.120310] [<f880cbb0>] ? dpms_show+0x60/0x60 [drm]
[75205.120317] [<c1425e0f>] dev_attr_show+0x1f/0x50
[75205.120324] [<c11e7d23>] sysfs_seq_show+0x103/0x1e0
[75205.120329] [<c1425df0>] ? root_device_unregister+0x30/0x30
[75205.120335] [<c11a38be>] seq_read+0xde/0x360
[75205.120340] [<c11850a4>] vfs_read+0x84/0x160
[75205.120345] [<c11a37e0>] ? seq_lseek+0x160/0x160
[75205.120350] [<c1185307>] SyS_read+0x57/0xa0
[75205.120355] [<c1695b8d>] sysenter_do_call+0x12/0x12
[75205.120361] [<c1680000>] ? ext4_check_descriptors+0x104/0x3b0
[75205.120364] ---[ end trace ed9b043f70466751 ]---
ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: chromium-browser 37.0.2062.120-0ubuntu0.12.04.1~pkg917
ProcVersionSignature: Ubuntu 3.13.0-39.66~precise1-generic 3.13.11.8
Uname: Linux 3.13.0-39-generic i686
ApportVersion: 2.0.1-0ubuntu17.8
Architecture: i386
Date: Sat Nov 1 23:36:56 2014
InstallationMedia: Ubuntu-Netbook 10.04 "Lucid Lynx" - Release i386 (20100429.4)
MarkForUpload: True
SourcePackage: chromium-browser
UpgradeStatus: No upgrade log present (probably fresh install)
modified.conffile..etc.default.chromium.browser: [deleted]
mtime.conffile..etc.chromium.browser.default: 2014-10-04T20:08:56.798366
m, thank you for reporting this and helping make Ubuntu better.
Could you please run the following command once from a terminal by ensuring you have the package xdiagnose installed, and that you click the Yes button for attaching additional debugging information:
apport-collect -p mesa 1388349