mm: mmu_gather: do not expose delayed_rmap flag

Flag delayed_rmap of 'struct mmu_gather' is rather a private member, but
it is still accessed directly.  Instead, let the TLB gather code access
the flag.

Link: https://lkml.kernel.org/r/Y3SWCu6NRaMQ5dbD@li-4a3a4a4c-28e5-11b2-a85c-a8d192c6f089.ibm.com
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory.c

@@ -1465,8 +1465,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 	/* Do the actual TLB flush before dropping ptl */
 	if (force_flush) {
 		tlb_flush_mmu_tlbonly(tlb);
-		if (tlb->delayed_rmap)
-			tlb_flush_rmaps(tlb, vma);
+		tlb_flush_rmaps(tlb, vma);
 	}
 	pte_unmap_unlock(start_pte, ptl);
 

mm/mmu_gather.c

@@ -61,6 +61,9 @@ void tlb_flush_rmaps(struct mmu_gather *tlb, struct vm_area_struct *vma)
 {
 	struct mmu_gather_batch *batch;
 
+	if (!tlb->delayed_rmap)
+		return;
+
 	batch = tlb->active;
 	for (int i = 0; i < batch->nr; i++) {
 		struct encoded_page *enc = batch->encoded_pages[i];