The stack guard page error case has long incorrectly caused a SIGBUS rather than a SIGSEGV, but nobody actually noticed until commit fee7e49d4514 ("mm: propagate error from stack expansion even for guard page") because that error case was never actually triggered in any normal situations. Now that we actually report the error, people noticed the wrong signal that resulted. So far, only the test suite of libsigsegv seems to have actually cared, but there are real applications that use libsigsegv, so let's not wait for any of those to break.
Unified · Split
| @@ -2632,7 +2632,7 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, · 2631 unmodified lines | |||
| 2632 | 2632 | ||
| 2633 | /* Check if we need to add a guard page to the stack */ | 2633 | /* Check if we need to add a guard page to the stack */ |
| 2634 | if (check_stack_guard_page(vma, address) < 0) | 2634 | if (check_stack_guard_page(vma, address) < 0) |
| 2635 | return VM_FAULT_SIGBUS; | 2635 | return VM_FAULT_SIGSEGV; |
| 2636 | 2636 | ||
| 2637 | /* Use the zero-page for reads */ | 2637 | /* Use the zero-page for reads */ |
| 2638 | if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm)) { | 2638 | if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm)) { |