Messages in this thread | | | Date | Sun, 10 Sep 2006 15:16:16 +0200 | From | Willy Tarreau <> | Subject | Re: Oops after 30 days of uptime |
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On Sun, Sep 10, 2006 at 12:43:25PM +0200, Ondrej Zary wrote: > On Sunday 10 September 2006 10:26, Willy Tarreau wrote: > > Hi Ondrej, > > > > OK, I've analysed your oops with your kernel. My conclusions are that you > > have a hardware problem (most probably the CPU), because you've hit an > > impossible case : > > > > ip_nat_cheat_check() pushed the size of the data (8) on the stack, followed > > by the pointer to the data, then called csum_partial() : > > > > c01e657f: 6a 08 push $0x8 > > c01e6581: 52 push %edx > > c01e6582: e8 a5 85 00 00 call c01eeb2c <csum_partial> > > > > In csum_partial(), ECX is filled with the size (8) and ESI with the data > > pointer (0xc0227ce8) : > > > > c01eeb32: 8b 4c 24 10 mov 0x10(%esp),%ecx > > c01eeb36: 8b 74 24 0c mov 0xc(%esp),%esi > > > > Then, the size is divided by 32 to count how many 32 bytes blocks can be > > read at a time. If the size is lower than 32, the code branches to a > > special location which reads 1 word at a time : > > > > c01eeb78: 89 ca mov %ecx,%edx > > c01eeb7a: c1 e9 05 shr $0x5,%ecx > > c01eeb7d: 74 32 je c01eebb1 <csum_partial+0x85> > > > > Your oops comes from a few instructions below. The branch has not been > > taken while it should have because (8 >> 5) == 0. You can also see from EDX > > in the oops that it really was 0x8 when copied from ECX. The rest is pretty > > obvious. The data are read 32 bytes at a time after ESI, and ECX is > > decreased by 1 every 32 bytes. When ESI+0x18 reaches an unmapped area > > (0xc2000000), you get the oops, and ECX = 0xfff113e8 as in your oops. > > > > Given that the failing instruction is the most common conditionnal jump, it > > is very fortunate that your system can work 30 days before crashing. I > > think that your CPU might be running too hot and might get wrong results > > during branch prediction. It's also possible that you have a poor power > > supply. However, I'm pretty sure that this is not a RAM problem. > > Thank you very much for the analysis. Good that it's not a kernel bug. > The CPU is 33MHz UMC GreenCPU which does not run hot even without a heatsink. > It's powered directly from 5V so it might be the power supply.
CPUs from this generation did not eat much power. I would find it strange that a glitch in the PSU causes trouble. Maybe you have dead capacitors on the motherboard close to the CPU (they would look bumped on the top).
Regards, Willy
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