Description of problem:

Firefox sometimes falls into a state when it has 100% CPU consumption for few seconds and then few seconds nothing and again.

This happens no matter whether there is or not any interaction with the browser. When the browser is used, such CPU usage peak freezes the UI (I  cannot even edit this text area).

Then I tried to find out which code is causing that, I have found very strange numbers:

# perf report
    10.87%     0.04%  firefox   [unknown]  [.] 0000000000000000
     8.07%     0.00%  firefox   [unknown]  [.] 0x00007f34ba6554e8
     4.78%     0.00%  firefox   [unknown]  [.] 0x00007f340e93f400
     4.53%     0.03%  firefox   libxul.so  [.] nsGenericHTMLElement::AddRef
     4.52%     0.00%  firefox   [unknown]  [.] 0x48f389485355fc89
     4.05%     0.00%  firefox   [unknown]  [.] 0x0000000000000001
     3.96%     0.00%  firefox   [unknown]  [.] 0x00007f34d85d1ce8
     3.65%     0.00%  firefox   [unknown]  [.] 0xeef8920e39e9be00
     3.30%     0.00%  firefox   libxul.so  [.] SnowWhiteKiller::Trace
     3.30%     0.00%  firefox   [unknown]  [.] 0x00007f34c218c000
     3.30%     0.00%  firefox   [unknown]  [.] 0x048b4864168b4818
     2.46%     2.45%  firefox   libxul.so  [.] nsCycleCollector::FreeSnowWhite
     2.25%     0.00%  firefox   [unknown]  [.] 0x630d8d4800042453
     2.11%     0.00%  firefox   [unknown]  [.] 0x002d007200610062
     2.05%     0.00%  firefox   [unknown]  [.] 0x358d48f3894853d5
     2.05%     0.03%  firefox   libxul.so  [.] nsPresContext::AddRef
     2.01%     0.00%  firefox   [unknown]  [.] 0x00e4d38c358d48f5

What is strange is that [unknown] DSO, since I have matching firefox-debuginfo installed, the 0000000000000000 is even more strange, however, even the correct addresses should be translated to function/method names, such as those from libxul.so. Thus, it looks like some code at 0 address from an unknown DSO is causing firefox freezes.

When attaching gdb to firefox during the peak, it also shows that there is a NULL-addresed code.

Restart helps, so firefox behaves normally again, but after some browsing, it falls to the freezing state again. It is very hard to debug, since I don't know how to reproduce the freezing state, probably the best thing is to have some important work to do in the browser, thus the chance of getting into it is higher.

The problem does not seem to be of a specific firefox version, it is somehow persistent across the versions.

It is annoying since it requires restarting FF again and again to fix it for some time.


Version-Release number of selected component (if applicable):
firefox-45.6.0-1.el7_3.x86_64

How reproducible:
often after some time of running

Steps to Reproduce:
unknown, just regular using with multiple tabs open

Actual results:


Expected results:


Additional info: