#include "internal.h"
-static inline bool check_pmd(struct page_vma_mapped_walk *pvmw)
-{
- pmd_t pmde;
- /*
- * Make sure we don't re-load pmd between present and !trans_huge check.
- * We need a consistent view.
- */
- pmde = READ_ONCE(*pvmw->pmd);
- return pmd_present(pmde) && !pmd_trans_huge(pmde);
-}
-
static inline bool not_found(struct page_vma_mapped_walk *pvmw)
{
page_vma_mapped_walk_done(pvmw);
pgd_t *pgd;
p4d_t *p4d;
pud_t *pud;
+ pmd_t pmde;
/* The only possible pmd mapping has been handled on last iteration */
if (pvmw->pmd && !pvmw->pte)
if (!pud_present(*pud))
return false;
pvmw->pmd = pmd_offset(pud, pvmw->address);
- if (pmd_trans_huge(*pvmw->pmd)) {
+ /*
+ * Make sure the pmd value isn't cached in a register by the
+ * compiler and used as a stale value after we've observed a
+ * subsequent update.
+ */
+ pmde = READ_ONCE(*pvmw->pmd);
+ if (pmd_trans_huge(pmde)) {
pvmw->ptl = pmd_lock(mm, pvmw->pmd);
if (!pmd_present(*pvmw->pmd))
return not_found(pvmw);
spin_unlock(pvmw->ptl);
pvmw->ptl = NULL;
}
- } else {
- if (!check_pmd(pvmw))
- return false;
+ } else if (!pmd_present(pmde)) {
+ return false;
}
if (!map_pte(pvmw))
goto next_pte;