On Wed, Jun 16, 2021 at 11:58 PM Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxx> wrote: > > $ dmesg > [ 166.864325] BUG: unable to handle page fault for address: 0000000000d12345 > [ 166.864336] #PF: supervisor read access in kernel mode > [ 166.864338] #PF: error_code(0x0000) - not-present page > > 0xd12345 is unallocated userspace address. Similarly, I also tried with that's unfortunately expected, since this is a user address. > p->dte = (void *)0xffffffffc1234567 after confirming it's not allocated > to kernel or any module address. I see the same failure with it too. This one is surprising though. Sounds like a bug in exception table construction. Can you debug it to see what's causing it? First check that do_kern_addr_fault() is invoked in this case. And then fixup_exception() and why search_bpf_extables() cannot find it. Separately we probably need to replace the NULL check with addr >= TASK_SIZE_MAX to close this issue though it's a bit artificial.
