On Mon 04-06-18 16:11:55, Dan Williams wrote:
> In support of enabling memory_failure() handling for device-dax
> mappings, set the ->mapping association of pages backing device-dax
> mappings. The rmap implementation requires page_mapping() to return the
> address_space hosting the vmas that map the page.
>
> The ->mapping pointer is never cleared. There is no possibility for the
> page to become associated with another address_space while the device is
> enabled. When the device is disabled the 'struct page' array for the
> device is destroyed / later reinitialized to zero.
>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Looks good to me. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> drivers/dax/device.c | 55 +++++++++++++++++++++++++++++++++++---------------
> 1 file changed, 38 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/dax/device.c b/drivers/dax/device.c
> index 686de08e120b..7ec246549721 100644
> --- a/drivers/dax/device.c
> +++ b/drivers/dax/device.c
> @@ -245,13 +245,12 @@ __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
> }
>
> static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax,
> - struct vm_fault *vmf)
> + struct vm_fault *vmf, pfn_t *pfn)
> {
> struct vm_area_struct *vma = vmf->vma;
> struct device *dev = &dev_dax->dev;
> struct dax_region *dax_region;
> phys_addr_t phys;
> - pfn_t pfn;
> unsigned int fault_size = PAGE_SIZE;
>
> if (check_vma(dev_dax, vma, __func__))
> @@ -273,13 +272,13 @@ static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax,
> return VM_FAULT_SIGBUS;
> }
>
> - pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
> + *pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
>
> - return vmf_insert_mixed(vma, vmf->address, pfn);
> + return vmf_insert_mixed(vma, vmf->address, *pfn);
> }
>
> static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax,
> - struct vm_fault *vmf)
> + struct vm_fault *vmf, pfn_t *pfn)
> {
> unsigned long pmd_addr = vmf->address & PMD_MASK;
> struct vm_area_struct *vma = vmf->vma;
> @@ -287,7 +286,6 @@ static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax,
> struct dax_region *dax_region;
> phys_addr_t phys;
> pgoff_t pgoff;
> - pfn_t pfn;
> unsigned int fault_size = PMD_SIZE;
>
> if (check_vma(dev_dax, vma, __func__))
> @@ -322,15 +320,15 @@ static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax,
> return VM_FAULT_SIGBUS;
> }
>
> - pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
> + *pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
>
> - return vmf_insert_pfn_pmd(vma, vmf->address, vmf->pmd, pfn,
> + return vmf_insert_pfn_pmd(vma, vmf->address, vmf->pmd, *pfn,
> vmf->flags & FAULT_FLAG_WRITE);
> }
>
> #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
> static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
> - struct vm_fault *vmf)
> + struct vm_fault *vmf, pfn_t *pfn)
> {
> unsigned long pud_addr = vmf->address & PUD_MASK;
> struct vm_area_struct *vma = vmf->vma;
> @@ -338,7 +336,6 @@ static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
> struct dax_region *dax_region;
> phys_addr_t phys;
> pgoff_t pgoff;
> - pfn_t pfn;
> unsigned int fault_size = PUD_SIZE;
>
>
> @@ -374,14 +371,14 @@ static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
> return VM_FAULT_SIGBUS;
> }
>
> - pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
> + *pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
>
> - return vmf_insert_pfn_pud(vma, vmf->address, vmf->pud, pfn,
> + return vmf_insert_pfn_pud(vma, vmf->address, vmf->pud, *pfn,
> vmf->flags & FAULT_FLAG_WRITE);
> }
> #else
> static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
> - struct vm_fault *vmf)
> + struct vm_fault *vmf, pfn_t *pfn)
> {
> return VM_FAULT_FALLBACK;
> }
> @@ -390,9 +387,11 @@ static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
> static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf,
> enum page_entry_size pe_size)
> {
> - int rc, id;
> struct vm_area_struct *vma = vmf->vma;
> struct file *filp = vma->vm_file;
> + unsigned long fault_size;
> + int rc, id;
> + pfn_t pfn;
> struct dev_dax *dev_dax = filp->private_data;
>
> dev_dbg(&dev_dax->dev, "%s: %s (%#lx - %#lx) size = %d\n", current->comm,
> @@ -402,17 +401,39 @@ static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf,
> id = dax_read_lock();
> switch (pe_size) {
> case PE_SIZE_PTE:
> - rc = __dev_dax_pte_fault(dev_dax, vmf);
> + fault_size = PAGE_SIZE;
> + rc = __dev_dax_pte_fault(dev_dax, vmf, &pfn);
> break;
> case PE_SIZE_PMD:
> - rc = __dev_dax_pmd_fault(dev_dax, vmf);
> + fault_size = PMD_SIZE;
> + rc = __dev_dax_pmd_fault(dev_dax, vmf, &pfn);
> break;
> case PE_SIZE_PUD:
> - rc = __dev_dax_pud_fault(dev_dax, vmf);
> + fault_size = PUD_SIZE;
> + rc = __dev_dax_pud_fault(dev_dax, vmf, &pfn);
> break;
> default:
> rc = VM_FAULT_SIGBUS;
> }
> +
> + if (rc == VM_FAULT_NOPAGE) {
> + unsigned long i;
> +
> + /*
> + * In the device-dax case the only possibility for a
> + * VM_FAULT_NOPAGE result is when device-dax capacity is
> + * mapped. No need to consider the zero page, or racing
> + * conflicting mappings.
> + */
> + for (i = 0; i < fault_size / PAGE_SIZE; i++) {
> + struct page *page;
> +
> + page = pfn_to_page(pfn_t_to_pfn(pfn) + i);
> + if (page->mapping)
> + continue;
> + page->mapping = filp->f_mapping;
> + }
> + }
> dax_read_unlock(id);
>
> return rc;
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
