+static vm_fault_t kvm_gmem_fault(struct vm_fault *vmf)
+{
+ struct folio *folio;
+
+ folio = kvm_gmem_get_folio(file_inode(vmf->vma->vm_file), vmf->pgoff);
+ if (!folio)
+ return VM_FAULT_SIGBUS;
+
+ /*
+ * Check if the page is allowed to be faulted to the host, with the
+ * folio lock held to ensure that the check and incrementing the page
+ * count are protected by the same folio lock.
+ */
+ if (!kvm_gmem_isfaultable(vmf)) {
+ folio_unlock(folio);
+ return VM_FAULT_SIGBUS;
+ }
+
+ vmf->page = folio_file_page(folio, vmf->pgoff);
We won't currently get hugetlb (or even THP) here. It mimics what shmem
would do.
finish_fault->set_pte_range() will call folio_add_file_rmap_ptes(),
getting the rmap involved.
Do we have some tests in place that make sure that
fallocate(FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE) will properly unmap
the page again (IOW, that the rmap does indeed work?).
--
Cheers,
David / dhildenb
