diff mbox series

[04/11] mm: allow a NULL fn callback in apply_to_page_range

Message ID 20201002122204.1534411-5-hch@lst.de (mailing list archive)
State Accepted
Commit eeb4a05fcef39a720d24846356cf65a07e71d7a1
Headers show
Series [01/11] mm: update the documentation for vfree | expand

Commit Message

Christoph Hellwig Oct. 2, 2020, 12:21 p.m. UTC 
Besides calling the callback on each page, apply_to_page_range also has
the effect of pre-faulting all PTEs for the range.  To support callers
that only need the pre-faulting, make the callback optional.

Based on a patch from Minchan Kim <minchan@kernel.org>.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/memory.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)
diff mbox series

Patch

diff --git a/mm/memory.c b/mm/memory.c
index fcfc4ca36eba80..dcf2bb69fbf847 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2420,13 +2420,15 @@  static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
 
 	arch_enter_lazy_mmu_mode();
 
-	do {
-		if (create || !pte_none(*pte)) {
-			err = fn(pte++, addr, data);
-			if (err)
-				break;
-		}
-	} while (addr += PAGE_SIZE, addr != end);
+	if (fn) {
+		do {
+			if (create || !pte_none(*pte)) {
+				err = fn(pte++, addr, data);
+				if (err)
+					break;
+			}
+		} while (addr += PAGE_SIZE, addr != end);
+	}
 	*mask |= PGTBL_PTE_MODIFIED;
 
 	arch_leave_lazy_mmu_mode();