diff options
| -rw-r--r-- | include/linux/mm_types.h | 3 | ||||
| -rw-r--r-- | mm/memory.c | 12 |
2 files changed, 14 insertions, 1 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 7216d77a5884..dd382270ae40 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -822,6 +822,8 @@ typedef struct { * @FAULT_FLAG_UNSHARE: The fault is an unsharing request to unshare (and mark * exclusive) a possibly shared anonymous page that is * mapped R/O. + * @FAULT_FLAG_ORIG_PTE_VALID: whether the fault has vmf->orig_pte cached. + * We should only access orig_pte if this flag set. * * About @FAULT_FLAG_ALLOW_RETRY and @FAULT_FLAG_TRIED: we can specify * whether we would allow page faults to retry by specifying these two @@ -858,6 +860,7 @@ enum fault_flag { FAULT_FLAG_INSTRUCTION = 1 << 8, FAULT_FLAG_INTERRUPTIBLE = 1 << 9, FAULT_FLAG_UNSHARE = 1 << 10, + FAULT_FLAG_ORIG_PTE_VALID = 1 << 11, }; #endif /* _LINUX_MM_TYPES_H */ diff --git a/mm/memory.c b/mm/memory.c index 9743c8b74bf2..878da420d97b 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4183,6 +4183,14 @@ void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr) set_pte_at(vma->vm_mm, addr, vmf->pte, entry); } +static bool vmf_pte_changed(struct vm_fault *vmf) +{ + if (vmf->flags & FAULT_FLAG_ORIG_PTE_VALID) + return !pte_same(*vmf->pte, vmf->orig_pte); + + return !pte_none(*vmf->pte); +} + /** * finish_fault - finish page fault once we have prepared the page to fault * @@ -4241,7 +4249,7 @@ vm_fault_t finish_fault(struct vm_fault *vmf) vmf->address, &vmf->ptl); ret = 0; /* Re-check under ptl */ - if (likely(pte_none(*vmf->pte))) + if (likely(!vmf_pte_changed(vmf))) do_set_pte(vmf, page, vmf->address); else ret = VM_FAULT_NOPAGE; @@ -4709,6 +4717,7 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf) * concurrent faults and from rmap lookups. */ vmf->pte = NULL; + vmf->flags &= ~FAULT_FLAG_ORIG_PTE_VALID; } else { /* * If a huge pmd materialized under us just retry later. Use @@ -4732,6 +4741,7 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf) */ vmf->pte = pte_offset_map(vmf->pmd, vmf->address); vmf->orig_pte = *vmf->pte; + vmf->flags |= FAULT_FLAG_ORIG_PTE_VALID; /* * some architectures can have larger ptes than wordsize, |