From: Kairui Song <kasong@xxxxxxxxxxx>
When folio is NULL, taking the address of its struct member is an
undefined behavior, the UB is caused by applying -> operator
to a pointer not pointing to any object. Although in practice this
won't lead to a real issue, still better to fix it, also makes the
code less error-prone, when folio is NULL, page is also NULL,
instead of a meanless offset value.
Signed-off-by: Kairui Song <kasong@xxxxxxxxxxx>
---
mm/memory.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/memory.c b/mm/memory.c
index e27e2e5beb3f..70ffa867b1be 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3861,7 +3861,6 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
/* skip swapcache */
folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0,
vma, vmf->address, false);
- page = &folio->page;
if (folio) {
__folio_set_locked(folio);
__folio_set_swapbacked(folio);
@@ -3879,6 +3878,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
workingset_refault(folio, shadow);
folio_add_lru(folio);
+ page = &folio->page;
/* To provide entry to swap_readpage() */
folio->swap = entry;
--
2.42.0
