tree 68fae5060333dcc24c17e9dd00a87bd760d883e9
parent 6f39ce056ab2ab2d29b2fae4aed61ed0b485972f
author Andi Kleen <ak@linux.intel.com> 1286394300 +0200
committer Andi Kleen <ak@linux.intel.com> 1286523166 +0200

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>