On 8/7/19 7:24 PM, 裘稀石(稀石) wrote: > Hi Mike, > > Do you mean the similar race is like the following? > > migration clearing the pte > page fault(before we return error, and now we return 0, then try page fault again, right?) > migration writing a migration entry Yes, something like the that. The change is to takes the page table lock to examine the pte before returning. If the pte is clear when examined while holding the lock, an error will be returned as before. If not clear, then we return zero and try again. This change adds code which is very much like this check further in the routine hugetlb_no_page(): ptl = huge_pte_lock(h, mm, ptep); size = i_size_read(mapping->host) >> huge_page_shift(h); if (idx >= size) goto backout; ret = 0; if (!huge_pte_none(huge_ptep_get(ptep))) goto backout; -- Mike Kravetz
