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    SubjectRe: [PATCH v8 05/22] Add vm_replace_mixed()
    On Tue 22-07-14 15:47:53, Matthew Wilcox wrote:
    > From: Matthew Wilcox <willy@linux.intel.com>
    >
    > vm_insert_mixed() will fail if there is already a valid PTE at that
    > location. The DAX code would rather replace the previous value with
    > the new PTE.
    >
    > Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
    This looks good to me although I'm not an expert in this area. So just:
    Acked-by: Jan Kara <jack@suse.cz>

    Honza

    > ---
    > include/linux/mm.h | 8 ++++++--
    > mm/memory.c | 34 +++++++++++++++++++++-------------
    > 2 files changed, 27 insertions(+), 15 deletions(-)
    >
    > diff --git a/include/linux/mm.h b/include/linux/mm.h
    > index e04f531..8d1194c 100644
    > --- a/include/linux/mm.h
    > +++ b/include/linux/mm.h
    > @@ -1958,8 +1958,12 @@ int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
    > int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *);
    > int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
    > unsigned long pfn);
    > -int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
    > - unsigned long pfn);
    > +int __vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
    > + unsigned long pfn, bool replace);
    > +#define vm_insert_mixed(vma, addr, pfn) \
    > + __vm_insert_mixed(vma, addr, pfn, false)
    > +#define vm_replace_mixed(vma, addr, pfn) \
    > + __vm_insert_mixed(vma, addr, pfn, true)
    > int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
    >
    >
    > diff --git a/mm/memory.c b/mm/memory.c
    > index 42bf429..cf06c97 100644
    > --- a/mm/memory.c
    > +++ b/mm/memory.c
    > @@ -1476,7 +1476,7 @@ pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
    > * pages reserved for the old functions anyway.
    > */
    > static int insert_page(struct vm_area_struct *vma, unsigned long addr,
    > - struct page *page, pgprot_t prot)
    > + struct page *page, pgprot_t prot, bool replace)
    > {
    > struct mm_struct *mm = vma->vm_mm;
    > int retval;
    > @@ -1492,8 +1492,12 @@ static int insert_page(struct vm_area_struct *vma, unsigned long addr,
    > if (!pte)
    > goto out;
    > retval = -EBUSY;
    > - if (!pte_none(*pte))
    > - goto out_unlock;
    > + if (!pte_none(*pte)) {
    > + if (!replace)
    > + goto out_unlock;
    > + VM_BUG_ON(!mutex_is_locked(&vma->vm_file->f_mapping->i_mmap_mutex));
    > + zap_page_range_single(vma, addr, PAGE_SIZE, NULL);
    > + }
    >
    > /* Ok, finally just insert the thing.. */
    > get_page(page);
    > @@ -1549,12 +1553,12 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
    > BUG_ON(vma->vm_flags & VM_PFNMAP);
    > vma->vm_flags |= VM_MIXEDMAP;
    > }
    > - return insert_page(vma, addr, page, vma->vm_page_prot);
    > + return insert_page(vma, addr, page, vma->vm_page_prot, false);
    > }
    > EXPORT_SYMBOL(vm_insert_page);
    >
    > static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
    > - unsigned long pfn, pgprot_t prot)
    > + unsigned long pfn, pgprot_t prot, bool replace)
    > {
    > struct mm_struct *mm = vma->vm_mm;
    > int retval;
    > @@ -1566,8 +1570,12 @@ static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
    > if (!pte)
    > goto out;
    > retval = -EBUSY;
    > - if (!pte_none(*pte))
    > - goto out_unlock;
    > + if (!pte_none(*pte)) {
    > + if (!replace)
    > + goto out_unlock;
    > + VM_BUG_ON(!mutex_is_locked(&vma->vm_file->f_mapping->i_mmap_mutex));
    > + zap_page_range_single(vma, addr, PAGE_SIZE, NULL);
    > + }
    >
    > /* Ok, finally just insert the thing.. */
    > entry = pte_mkspecial(pfn_pte(pfn, prot));
    > @@ -1620,14 +1628,14 @@ int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
    > if (track_pfn_insert(vma, &pgprot, pfn))
    > return -EINVAL;
    >
    > - ret = insert_pfn(vma, addr, pfn, pgprot);
    > + ret = insert_pfn(vma, addr, pfn, pgprot, false);
    >
    > return ret;
    > }
    > EXPORT_SYMBOL(vm_insert_pfn);
    >
    > -int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
    > - unsigned long pfn)
    > +int __vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
    > + unsigned long pfn, bool replace)
    > {
    > BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
    >
    > @@ -1645,11 +1653,11 @@ int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
    > struct page *page;
    >
    > page = pfn_to_page(pfn);
    > - return insert_page(vma, addr, page, vma->vm_page_prot);
    > + return insert_page(vma, addr, page, vma->vm_page_prot, replace);
    > }
    > - return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
    > + return insert_pfn(vma, addr, pfn, vma->vm_page_prot, replace);
    > }
    > -EXPORT_SYMBOL(vm_insert_mixed);
    > +EXPORT_SYMBOL(__vm_insert_mixed);
    >
    > /*
    > * maps a range of physical memory into the requested pages. the old
    > --
    > 2.0.0
    >
    > --
    > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
    > the body of a message to majordomo@vger.kernel.org
    > More majordomo info at http://vger.kernel.org/majordomo-info.html
    --
    Jan Kara <jack@suse.cz>
    SUSE Labs, CR


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