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/memory.c b/mm/memory.c
index 0e18b4d..c2d6dd3 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1450,7 +1450,8 @@
if (ret & VM_FAULT_OOM)
return i ? i : -ENOMEM;
if (ret &
- (VM_FAULT_HWPOISON|VM_FAULT_SIGBUS))
+ (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE|
+ VM_FAULT_SIGBUS))
return i ? i : -EFAULT;
BUG();
}