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device-dax: Enable page_mapping()

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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.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
This commit is contained in:
Dan Williams 2018-07-13 21:49:40 -07:00 committed by Dave Jiang
parent 226ab56107
commit 2232c6382a
1 changed files with 38 additions and 17 deletions
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55
drivers/dax/device.c
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@ -245,12 +245,11 @@ __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 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, vmf->vma, __func__))
@ -272,20 +271,19 @@ 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(vmf->vma, vmf->address, pfn);
return vmf_insert_mixed(vmf->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 device *dev = &dev_dax->dev;
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, vmf->vma, __func__))
@ -321,22 +319,21 @@ 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(vmf->vma, vmf->address, vmf->pmd, pfn,
return vmf_insert_pfn_pmd(vmf->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 device *dev = &dev_dax->dev;
struct dax_region *dax_region;
phys_addr_t phys;
pgoff_t pgoff;
pfn_t pfn;
unsigned int fault_size = PUD_SIZE;
@ -373,14 +370,14 @@ 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(vmf->vma, vmf->address, vmf->pud, pfn,
return vmf_insert_pfn_pud(vmf->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;
}
@ -389,8 +386,10 @@ 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 file *filp = vmf->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,
@ -400,17 +399,39 @@ 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;