Messages in this thread | | | Date | Tue, 04 Jun 2013 09:53:21 -0700 | From | Ben Greear <> | Subject | Re: Please add to stable: module: don't unlink the module until we've removed all exposure. |
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On 06/04/2013 07:07 AM, Joe Lawrence wrote: > On Tue, 04 Jun 2013 15:26:28 +0930 > Rusty Russell <rusty@rustcorp.com.au> wrote: > >> Do you have a backtrace of the 3.9.4 crash? You can add "CFLAGS_module.o >> = -O0" to get a clearer backtrace if you want... > > Hi Rusty, > > See my 3.9 stack traces below, which may or may not be what Ben had > been seeing. If you like, I can try a similar loop as the one you were > testing in the other email.
My stack traces are similar. I had better luck reproducing the problem once I enabled lots of debugging (slub memory poisoning, lockdep, object debugging, etc).
I'm using Fedora 17 on 2-core core-i7 (4 CPU threads total) for most of this testing. We reproduced on dual-core Atom system as well (32-bit Fedora 14 and Fedora 17). Relatively standard hardware as far as I know.
I'll run the insmod/rmmod stress test on my patched systems and see if I can reproduce with the patch in the title applied.
Rusty: I'm also seeing lockups related to migration on stock 3.9.4+ (with and without the 'don't unlink the module...' patch. Much harder to reproduce. But, that code appears to be mostly called during module load/unload, so it's possible it is related. The first traces are from a system with local patches, applied, but a later post by me has traces from clean upstream kernel.
Further debugging showed that this could be a race, because it seems that all migration/ threads think they are done with their state machine, but the atomic thread counter sits at 1, so no progress is ever made.
http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg443471.html
Thanks, Ben
-- Ben Greear <greearb@candelatech.com> Candela Technologies Inc http://www.candelatech.com
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