On 03/04/2018 01:12, David Rientjes wrote:
> On Tue, 13 Mar 2018, Laurent Dufour wrote:
>
>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>> index dfa81a638b7c..a84ddc218bbd 100644
>> --- a/include/linux/mm.h
>> +++ b/include/linux/mm.h
>> @@ -684,13 +684,18 @@ void free_compound_page(struct page *page);
>> * pte_mkwrite. But get_user_pages can cause write faults for mappings
>> * that do not have writing enabled, when used by access_process_vm.
>> */
>> -static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
>> +static inline pte_t __maybe_mkwrite(pte_t pte, unsigned long vma_flags)
>> {
>> - if (likely(vma->vm_flags & VM_WRITE))
>> + if (likely(vma_flags & VM_WRITE))
>> pte = pte_mkwrite(pte);
>> return pte;
>> }
>>
>> +static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
>> +{
>> + return __maybe_mkwrite(pte, vma->vm_flags);
>> +}
>> +
>> int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
>> struct page *page);
>> int finish_fault(struct vm_fault *vmf);
>> diff --git a/mm/memory.c b/mm/memory.c
>> index 0a0a483d9a65..af0338fbc34d 100644
>> --- a/mm/memory.c
>> +++ b/mm/memory.c
>> @@ -2472,7 +2472,7 @@ static inline void wp_page_reuse(struct vm_fault *vmf)
>>
>> flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
>> entry = pte_mkyoung(vmf->orig_pte);
>> - entry = maybe_mkwrite(pte_mkdirty(entry), vma);
>> + entry = __maybe_mkwrite(pte_mkdirty(entry), vmf->vma_flags);
>> if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
>> update_mmu_cache(vma, vmf->address, vmf->pte);
>> pte_unmap_unlock(vmf->pte, vmf->ptl);
>> @@ -2549,8 +2549,8 @@ static int wp_page_copy(struct vm_fault *vmf)
>> inc_mm_counter_fast(mm, MM_ANONPAGES);
>> }
>> flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
>> - entry = mk_pte(new_page, vma->vm_page_prot);
>> - entry = maybe_mkwrite(pte_mkdirty(entry), vma);
>> + entry = mk_pte(new_page, vmf->vma_page_prot);
>> + entry = __maybe_mkwrite(pte_mkdirty(entry), vmf->vma_flags);
>> /*
>> * Clear the pte entry and flush it first, before updating the
>> * pte with the new entry. This will avoid a race condition
>
> Don't you also need to do this in do_swap_page()?
Indeed I'll drop this patch as all the changes are now done in the patch 11
"mm: Cache some VMA fields in the vm_fault structure" where, as you suggested,
maybe_mkwrite() is now getting passed the vm_flags value directly.
> diff --git a/mm/memory.c b/mm/memory.c
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3067,9 +3067,9 @@ int do_swap_page(struct vm_fault *vmf)
>
> inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
> dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
> - pte = mk_pte(page, vma->vm_page_prot);
> + pte = mk_pte(page, vmf->vma_page_prot);
> if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
> - pte = maybe_mkwrite(pte_mkdirty(pte), vma);
> + pte = __maybe_mkwrite(pte_mkdirty(pte), vmf->vma_flags);
> vmf->flags &= ~FAULT_FLAG_WRITE;
> ret |= VM_FAULT_WRITE;
> exclusive = RMAP_EXCLUSIVE;
>
