On Tue, 13 Mar 2018, Laurent Dufour wrote: > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 2f3e98edc94a..b6432a261e63 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1199,6 +1199,7 @@ static inline void clear_page_pfmemalloc(struct page > *page) > #define VM_FAULT_NEEDDSYNC 0x2000 /* ->fault did not modify page tables > * and needs fsync() to complete (for > * synchronous page faults in DAX) */ > +#define VM_FAULT_PTNOTSAME 0x4000 /* Page table entries have changed */ > > #define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | > VM_FAULT_SIGSEGV | \ > VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE | \ > diff --git a/mm/memory.c b/mm/memory.c > index 21b1212a0892..4bc7b0bdcb40 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -2309,21 +2309,29 @@ static bool pte_map_lock(struct vm_fault *vmf) > * parts, do_swap_page must check under lock before unmapping the pte and > * proceeding (but do_wp_page is only called after already making such a > check; > * and do_anonymous_page can safely check later on). > + * > + * pte_unmap_same() returns: > + * 0 if the PTE are the same > + * VM_FAULT_PTNOTSAME if the PTE are different > + * VM_FAULT_RETRY if the VMA has changed in our back during > + * a speculative page fault handling. > */ > -static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, > - pte_t *page_table, pte_t orig_pte) > +static inline int pte_unmap_same(struct vm_fault *vmf) > { > - int same = 1; > + int ret = 0; > + > #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) > if (sizeof(pte_t) > sizeof(unsigned long)) { > - spinlock_t *ptl = pte_lockptr(mm, pmd); > - spin_lock(ptl); > - same = pte_same(*page_table, orig_pte); > - spin_unlock(ptl); > + if (pte_spinlock(vmf)) { > + if (!pte_same(*vmf->pte, vmf->orig_pte)) > + ret = VM_FAULT_PTNOTSAME; > + spin_unlock(vmf->ptl); > + } else > + ret = VM_FAULT_RETRY; > } > #endif > - pte_unmap(page_table); > - return same; > + pte_unmap(vmf->pte); > + return ret; > } > > static inline void cow_user_page(struct page *dst, struct page *src, > unsigned long va, struct vm_area_struct *vma) > @@ -2913,7 +2921,8 @@ int do_swap_page(struct vm_fault *vmf) > int exclusive = 0; > int ret = 0;
Initialization is now unneeded. Otherwise: Acked-by: David Rientjes <rient...@google.com>