Re: Random panic in load_balance() with 3.16-rc

Linus Torvalds
2014-07-26T18:28:13Z

On Fri, Jul 25, 2014 at 11:29 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> I'm sure it's possible, but it sounds potentially complicated.

Hmm. The bugzilla entry just taught me a new gcc flag:
"-fcompare-debug". That apparently makes gcc compile things twice,
once with debugging and once without, and verify that the result is
the same.

And you can enable it for the whole kernel build with just a simple

export GCC_COMPARE_DEBUG=1

before doing the build.

It actually results in a failure for me even on my standard small
localized kernel build, even with gcc-4.8.3. I get a compare failure
for (at least) fs/ext4/inode.c.

That's a bit worrisome. I haven't actually checked if the code
generation differs in significant ways yet..

Linus