diff options
Diffstat (limited to 'mm/page_vma_mapped.c')
-rw-r--r-- | mm/page_vma_mapped.c | 50 |
1 files changed, 33 insertions, 17 deletions
diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index 8ec6ba2..53afbb9 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -6,17 +6,6 @@ #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); @@ -48,6 +37,7 @@ static bool check_pte(struct page_vma_mapped_walk *pvmw) if (!is_swap_pte(*pvmw->pte)) return false; entry = pte_to_swp_entry(*pvmw->pte); + if (!is_migration_entry(entry)) return false; if (migration_entry_to_page(entry) - pvmw->page >= @@ -60,6 +50,15 @@ static bool check_pte(struct page_vma_mapped_walk *pvmw) WARN_ON_ONCE(1); #endif } else { + if (is_swap_pte(*pvmw->pte)) { + swp_entry_t entry; + + entry = pte_to_swp_entry(*pvmw->pte); + if (is_device_private_entry(entry) && + device_private_entry_to_page(entry) == pvmw->page) + return true; + } + if (!pte_present(*pvmw->pte)) return false; @@ -106,6 +105,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *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) @@ -138,24 +138,40 @@ restart: 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) || is_pmd_migration_entry(pmde)) { pvmw->ptl = pmd_lock(mm, pvmw->pmd); - if (!pmd_present(*pvmw->pmd)) - return not_found(pvmw); if (likely(pmd_trans_huge(*pvmw->pmd))) { if (pvmw->flags & PVMW_MIGRATION) return not_found(pvmw); if (pmd_page(*pvmw->pmd) != page) return not_found(pvmw); return true; + } else if (!pmd_present(*pvmw->pmd)) { + if (thp_migration_supported()) { + if (!(pvmw->flags & PVMW_MIGRATION)) + return not_found(pvmw); + if (is_migration_entry(pmd_to_swp_entry(*pvmw->pmd))) { + swp_entry_t entry = pmd_to_swp_entry(*pvmw->pmd); + + if (migration_entry_to_page(entry) != page) + return not_found(pvmw); + return true; + } + } + return not_found(pvmw); } else { /* THP pmd was split under us: handle on pte level */ 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; |