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.. Thanks, Fengguang -- 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>