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? -- Regards/Gruss, Boris. Advanced Micro Devices GmbH Einsteinring 24, 85609 Dornach GM: Alberto Bozzo Reg: Dornach, Landkreis Muenchen HRB Nr. 43632 WEEE Registernr: 129 19551 -- 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>