On 01/25/2018, 04:12 PM, Greg Kroah-Hartman wrote: > On Thu, Jan 25, 2018 at 03:47:32PM +0100, Jiri Slaby wrote: >> On 01/25/2018, 03:30 PM, Thomas Gleixner wrote: >>> So what's the problem? >> >> The problem I see is that every stable kernel now requires updated >> strace with their commit from yesterday to build correctly. In >> particular, the new stable kernels cause rpm build failures of strace in >> all our distros (based on those stable kernels). Sure, we can patch >> strace in every distro every nth kernel update, but it's mere >> impractical. Kernel should not break userspace, right? > > Well, when userspace is doing something stupid... :) No doubt... But does that mean we no longer maintain the "no userspace breakage even if it is stupid" rule? >> BTW why was the patch applied to stable? We actually do pass >> -fno-strict-overflow. > > The same reason it was applied upstream, it fixes a reported > issue. > > Does that mean that all UBSAN overflow error reports are not valid > because of how we build the kernel? IMO yes, because with the option, signed overflow is not undefined. In the long term, it would be nice to get rid of *all* signed integer overflows and kill the compiler option from Makefile. Therefore the fixes are indeed very valid in upstream. thanks, -- js suse labs