On 08/27/2017 05:48 AM, Kirill A. Shutemov wrote:

quoted

+	/* Transparent huge pages are not supported. */
+	if (unlikely(pmd_trans_huge(*pmd)))
+		goto out_walk;

That's looks like a blocker to me.

Is there any problem with making it supported (besides plain coding)?

IIUC we would have to reattempt once for each PMD level fault because
of the lack of a page table entry there. Besides do we want to support
huge pages in general as part of speculative page fault path ? The
number of faults will be very less (256 times lower on POWER and 512
times lower on X86). So is it worth it ? BTW calling hugetlb_fault()
after figuring out the VMA, works correctly inside handle_speculative
_fault() last time I checked.