Messages in this thread | | | Date | Mon, 28 Jul 2014 20:09:02 +0200 | From | Markus Trippelsdorf <> | Subject | Re: Random panic in load_balance() with 3.16-rc |
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On 2014.07.28 at 10:27 -0700, Alexei Starovoitov wrote: > On Mon, Jul 28, 2014 at 09:45:45AM -0700, Linus Torvalds wrote: > > On Mon, Jul 28, 2014 at 5:26 AM, Frank Ch. Eigler <fche@redhat.com> wrote: > > > > > > Please note that the data produced by "-g -fvar-tracking" is consumed > > > by tools like systemtap, perf, crash, and makes a significant > > > difference to the observability of debug AND non-debug kernels. > > > > Yeah, and compared to having a buggy kernel, I care exactly this much: "". > > It's not pretty, but adding it unconditionally was the right thing to do. > Black listing compiler versions is too fragile. > Look at the flip side: now size of build dir will be much smaller :)
It shouldn't be too hard to implement a simple check for the bug in the next release. Just compile the gcc/testsuite/gcc.target/i386/pr61801.c testcase with -fcompare-debug. If gcc returns 0 then -fvar-tracking-assignments could safely be enabled again.
Here's the testcase:
int a, b, c; void fn1 () { int d; if (fn2 () && !0) { b = ( { int e; fn3 (); switch (0) default: asm volatile("" : "=a"(e) : "0"(a), "i"(0)); e; }); d = b; } c = d; }
-- Markus
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