title: How to investigate runtime Linux Kernel warning
body: <p>My device is running a software based on Linux Kernel 2.6.32.
  There was an occurrence of Kernel warning as follow: </p>
  
  <pre><code>WARNING,Aug 27 21:55:09,"------------[ cut here ]------------"
  WARNING,Aug 27 21:55:09,"WARNING: at net/sched/sch_generic.c:255 dev_watchdog+0x144/0x224()"
  INFORMATIONAL,Aug 27 21:55:09,"NETDEV WATCHDOG: eth1 (cdc_ether): transmit queue 0 timed out"
  WARNING,Aug 27 21:55:09,"Modules linked in: GobiSerial GobiNet g_ether leddrv cryptr_micro gpio_event_drv [last unloaded: wlan]"
  WARNING,Aug 27 21:55:09,"[&lt;c0a7b518&gt;] (unwind_backtrace+0x0/0xdc) from [&lt;c0a9cfb0&gt;] (warn_slowpath_common+0x48/0x60)"
  WARNING,Aug 27 21:55:09,"[&lt;c0a9cfb0&gt;] (warn_slowpath_common+0x48/0x60) from [&lt;c0a9d000&gt;] (warn_slowpath_fmt+0x24/0x30)"
  WARNING,Aug 27 21:55:09,"[&lt;c0a9d000&gt;] (warn_slowpath_fmt+0x24/0x30) from [&lt;c0ccae98&gt;] (dev_watchdog+0x144/0x224)"
  WARNING,Aug 27 21:55:09,"[&lt;c0ccae98&gt;] (dev_watchdog+0x144/0x224) from [&lt;c0aa56a8&gt;] (run_timer_softirq+0x138/0x1b4)"
  WARNING,Aug 27 21:55:09,"[&lt;c0aa56a8&gt;] (run_timer_softirq+0x138/0x1b4) from [&lt;c0aa1a60&gt;] (__do_softirq+0x70/0xf4)"
  WARNING,Aug 27 21:55:09,"[&lt;c0aa1a60&gt;] (__do_softirq+0x70/0xf4) from [&lt;c0aa1b24&gt;] (irq_exit+0x40/0x8c)"
  WARNING,Aug 27 21:55:09,"[&lt;c0aa1b24&gt;] (irq_exit+0x40/0x8c) from [&lt;c0a75070&gt;] (asm_do_IRQ+0x70/0x8c)"
  WARNING,Aug 27 21:55:09,"[&lt;c0a75070&gt;] (asm_do_IRQ+0x70/0x8c) from [&lt;c0a75a70&gt;] (__irq_svc+0x30/0x80)"
  WARNING,Aug 27 21:55:09,"Exception stack(0xc0ed7f80 to 0xc0ed7fc8)"
  WARNING,Aug 27 21:55:09,"7f80: 00000000 40000013 00712778 00003505 c0ed6000 c0f11f1c c0a6d3f4 c0ed9bd8"
  WARNING,Aug 27 21:55:09,"7fa0: 80027104 411fc087 0000001f 00000000 c0edb8e0 c0ed7fc8 c0a85cc4 c0a864a4"
  WARNING,Aug 27 21:55:09,"7fc0: 60000013 ffffffff"
  WARNING,Aug 27 21:55:09,"[&lt;c0a75a70&gt;] (__irq_svc+0x30/0x80) from [&lt;c0a864a4&gt;] (omap3_pm_idle+0x48/0x4c)"
  WARNING,Aug 27 21:55:09,"[&lt;c0a864a4&gt;] (omap3_pm_idle+0x48/0x4c) from [&lt;c0a773e4&gt;] (cpu_idle+0x48/0x88)"
  WARNING,Aug 27 21:55:09,"[&lt;c0a773e4&gt;] (cpu_idle+0x48/0x88) from [&lt;c0008a68&gt;] (start_kernel+0x234/0x28c)"
  WARNING,Aug 27 21:55:09,"[&lt;c0008a68&gt;] (start_kernel+0x234/0x28c) from [&lt;80008034&gt;] (0x80008034)"
  WARNING,Aug 27 21:55:09,"---[ end trace 7fe9ba4a7fb84cb4 ]---"
  </code></pre>
  
  <p>It does not occur often, but when it does the modules connected to eth1 do not work properly and only device reboot helps.</p>
  
  <p>What is the procedure to investigated such a Kernel issue, or to find an eventual patch(es) related to this in later Kernel versions?</p>
  
  <p>Thanks.</p>