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    SubjectRe: [PATCH v9 14/24] mm: Introduce __maybe_mkwrite()
    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()?

    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;
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      Last update: 2018-04-03 01:12    [W:4.047 / U:0.024 seconds]
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