Encode huge page size for VM_FAULT_HWPOISON errors
This fixes a problem introduced with the hugetlb hwpoison handling
The user space SIGBUS signalling wants to know the size of the hugepage
that caused a HWPOISON fault.
Unfortunately the architecture page fault handlers do not have easy
access to the struct page.
Pass the information out in the fault error code instead.
I added a separate VM_FAULT_HWPOISON_LARGE bit for this case and encode
the hpage index in some free upper bits of the fault code. The small
page hwpoison keeps stays with the VM_FAULT_HWPOISON name to minimize
changes.
Also add code to hugetlb.h to convert that index into a page shift.
Will be used in a further patch.
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: fengguang.wu@intel.com
Signed-off-by: Andi Kleen <ak@linux.intel.com>
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 67cd032..96991de 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2589,7 +2589,8 @@
* So we need to block hugepage fault by PG_hwpoison bit check.
*/
if (unlikely(PageHWPoison(page))) {
- ret = VM_FAULT_HWPOISON;
+ ret = VM_FAULT_HWPOISON |
+ VM_FAULT_SET_HINDEX(h - hstates);
goto backout_unlocked;
}
page_dup_rmap(page);
@@ -2656,7 +2657,8 @@
migration_entry_wait(mm, (pmd_t *)ptep, address);
return 0;
} else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
- return VM_FAULT_HWPOISON;
+ return VM_FAULT_HWPOISON_LARGE |
+ VM_FAULT_SET_HINDEX(h - hstates);
}
ptep = huge_pte_alloc(mm, address, huge_page_size(h));