Messages in this thread | | | Date | Fri, 3 Feb 2012 20:46:23 -0600 | Subject | Re: [perf] perf top segfaulting | From | Dan McGee <> |
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On Fri, Feb 3, 2012 at 8:24 PM, David Daney <david.daney@cavium.com> wrote: > On 02/03/2012 04:45 PM, Dan McGee wrote: >> >> On i686, version 3.2-2, but looks like annotate.c hasn't changed much >> since. It sometimes happens within 5 seconds of starting perf, >> sometimes much later, but almost always if I leave it running I well >> come back to it having segfaulted. When ran with gdb here it took >> about 3 minutes; I had a 5 second segfault and a 5 minute segfault >> before and after this run as well. I'm not sure what triggers it other >> than it isn't user input, as I can start `perf top`, not touch it, and >> it will eventually segfault. >> > > > I have seen the same thing (basically the same stack trace), so I think what > I see is probably closely related. My failures however are on mips64 based > systems. > > My debugging suggests that this happens when the ABIs used by the running > processes are heterogeneous (A mixture of 32-bit and 64-bit processes). > What I see is that all processes use a library with a common name, but > differing in paths (/lib32/libc-2.11.3.so and /lib64/libc-2.11.3.so for > example). It looks like perf is confusing the offsets it caches from one > library to look up information in the other and since the symbols are in > different locations, the resulting erroneous address calculations result in > accesses to unmapped portions of perf's address space and you get SIGSEGV. > > I haven't dug into the code enough to suggest a fix, but I think that at a > high hand-waving level, this is what is happening. I have never observed > the failure when using only a single ABI on the system
Note that in this case, it is a pure 32-bit x86 system, and no library changes were going on in the background. So I wouldn't be surprised if the causes are similar (or the same), but I don't think I can chalk it up to being a single ABI vs multiple ABI problem; i686 only has one ABI.
-Dan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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