Ralf Baechle wrote: > On Fri, May 03, 2002 at 02:46:19PM -0700, Jun Sun wrote: > > >>When running LTP, I notice that recent kernel has a kernel access fault: >> >><1>Unable to handle kernel paging request at virtual address 00000000, epc >>== 80273860, ra == 80205aa4 >> > > Well, decode the oops message. The question is what is at 0x80273860? > 0x80273860 is copy_bytes in arch/mips/lib/memcpy.S, which is reached through __copy_user. The faulting instruction, not suprisingly, is writing a byte to the destination at 0x0. Anybody can try to call copy_to_user(0x0, ...) inside kernel and see the scene. The question here is whether we should reach do_page_fault() and terminate calling process or try to catch the fault and return some meaningful error. It appears earlier version of kernel does not have this problem. I have not fully figured out why. Jun
