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/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 796f30e..943c76b 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -307,6 +307,11 @@
return size_to_hstate(PAGE_SIZE << compound_order(page));
}
+static inline unsigned hstate_index_to_shift(unsigned index)
+{
+ return hstates[index].order + PAGE_SHIFT;
+}
+
#else
struct hstate {};
#define alloc_huge_page_node(h, nid) NULL
@@ -324,6 +329,7 @@
{
return 1;
}
+#define hstate_index_to_shift(index) 0
#endif
#endif /* _LINUX_HUGETLB_H */