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>
---
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;
