On 09/24/2012 06:26 PM, Borislav Petkov wrote: > On Mon, Sep 24, 2012 at 08:29:00PM +0800, Fengguang Wu wrote: >> On Mon, Sep 24, 2012 at 02:20:53PM +0200, Borislav Petkov wrote: >>> On Mon, Sep 24, 2012 at 07:34:47PM +0800, Fengguang Wu wrote: >>>> Will you test such a line? At least the generic do_div() only uses the >>>> lower 32bits for division. >>>> >>>> WARN_ON(!(den & 0xffffffff)); >>> >>> But, but, the asm output says: >>> >>> 28: 48 89 c8 mov %rcx,%rax >>> 2b:* 48 f7 f7 div %rdi <-- trapping instruction >>> 2e: 31 d2 xor %edx,%edx >>> >>> and this version of DIV does an unsigned division of RDX:RAX by the >>> contents of a *64-bit register* ... in our case %rdi. >>> >>> Srivatsa's oops shows the same: >>> >>> 28: 48 89 f0 mov %rsi,%rax >>> 2b:* 48 f7 f7 div %rdi <-- trapping instruction >>> 2e: 41 8b 94 24 74 02 00 mov 0x274(%r12),%edx >>> >>> Right? >> >> Right, that's why I said "at least". As for x86, I'm as clueless as you.. > > Right, both oopses are on x86 so I don't think it is the bitness of the > division. > > Another thing those two have in common is that both happen when a CPU > comes online. Srivatsa's is when CPU9 comes online (oops is detected on > CPU9) and in our case CPU4 comes online but the oops says CPU0. > I had posted another dump from one of my tests. That one triggers while offlining a CPU (CPU 9). https://lkml.org/lkml/2012/9/14/235 > So it has to be hotplug-related. Regards, Srivatsa S. Bhat -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>