On Tue, Nov 5, 2024 at 12:18 PM Ilya Leoshkevich <iii@xxxxxxxxxxxxx> wrote: > > On Tue, 2024-11-05 at 12:30 +0800, Hou Tao wrote: > > From: Hou Tao <houtao1@xxxxxxxxxx> > > > > As reported by Byeonguk, the bad_words test in verifier_bits_iter.c > > occasionally fails on s390 host. Quoting Ilya's explanation: > > > > s390 kernel runs in a completely separate address space, there is > > no > > user/kernel split at TASK_SIZE. The same address may be valid in > > both > > the kernel and the user address spaces, there is no way to tell by > > looking at it. The config option related to this property is > > ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE. > > > > Also, unfortunately, 0 is a valid address in the s390 kernel > > address > > space. > > > > Fix the issue by using -4096 as the bad address for bits iterator, as > > suggested by Ilya. Verify that bpf_iter_bits_new() returns -EINVAL > > for > > NULL address and -EFAULT for bad address. > > The code uses -4095, which I think is better, since it's the current > value of MAX_ERRNO, therefore, IS_ERR_VALUE() sees it as an error. It's > also not aligned, which may be an additional reason it may not be > dereferenceable on some CPUs. > > Other than this discrepancy in the commit message: > > Acked-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx> Fixed it up while applying.
