On Fri, Sep 16, 2016 at 03:47:04PM -0700, Guenter Roeck wrote: > Adding pr_info() just before the "if (unlikely..." fixes the problem. > > Commenting out the "if (unlikely())" code fixes the problem. > > Using a new variable "unsigned long x" for the return code instead of > re-using __copy_size fixes the problem. > > Replacing "return __copy_size;" with "return __copy_size & 0xffffffff;" > fixes the problem. > > The problem only seems to be seen if the copy size length is odd (more > specifically, the failing copy always has a length of 25 bytes). > > No idea what is going on. Bug in __copy_user() ? Compiler bug ?
Definitely a compiler bug. __kernel_size_t is 32 bits on sh; that & 0xffffffff should've been optimized away, for crying out loud!
