[033/146] device-dax: set mapping prior to vmf_insert_pfn{,_pmd,pud}()

Commit Message

Andrew Morton Jan. 14, 2022, 10:04 p.m. UTC

From: Joao Martins <[e-mail]>
Subject: device-dax: set mapping prior to vmf_insert_pfn{,_pmd,pud}()

Normally, the @page mapping is set prior to inserting the page into a page
table entry.  Make device-dax adhere to the same ordering, rather than
setting mapping after the PTE is inserted.

The address_space never changes and it is always associated with the same
inode and underlying pages.  So, the page mapping is set once but cleared
when the struct pages are removed/freed (i.e.  after
{devm_}memunmap_pages()).

Link: https://lkml.kernel.org/r/[e-mail]
Suggested-by: Jason Gunthorpe <[e-mail]>
Signed-off-by: Joao Martins <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Dan Williams <[e-mail]>
Cc: Dave Jiang <[e-mail]>
Cc: Jane Chu <[e-mail]>
Cc: Jason Gunthorpe <[e-mail]>
Cc: John Hubbard <[e-mail]>
Cc: Jonathan Corbet <[e-mail]>
Cc: Matthew Wilcox (Oracle) <[e-mail]>
Cc: Mike Kravetz <[e-mail]>
Cc: Muchun Song <[e-mail]>
Cc: Naoya Horiguchi <[e-mail]>
Cc: Vishal Verma <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 drivers/dax/device.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Patch

--- a/drivers/dax/device.c~device-dax-set-mapping-prior-to-vmf_insert_pfn_pmdpud
+++ a/drivers/dax/device.c
@@ -121,6 +121,8 @@  static vm_fault_t __dev_dax_pte_fault(st
 
 	*pfn = phys_to_pfn_t(phys, PFN_DEV|PFN_MAP);
 
+	dax_set_mapping(vmf, *pfn, fault_size);
+
 	return vmf_insert_mixed(vmf->vma, vmf->address, *pfn);
 }
 
@@ -161,6 +163,8 @@  static vm_fault_t __dev_dax_pmd_fault(st
 
 	*pfn = phys_to_pfn_t(phys, PFN_DEV|PFN_MAP);
 
+	dax_set_mapping(vmf, *pfn, fault_size);
+
 	return vmf_insert_pfn_pmd(vmf, *pfn, vmf->flags & FAULT_FLAG_WRITE);
 }
 
@@ -203,6 +207,8 @@  static vm_fault_t __dev_dax_pud_fault(st
 
 	*pfn = phys_to_pfn_t(phys, PFN_DEV|PFN_MAP);
 
+	dax_set_mapping(vmf, *pfn, fault_size);
+
 	return vmf_insert_pfn_pud(vmf, *pfn, vmf->flags & FAULT_FLAG_WRITE);
 }
 #else
@@ -217,7 +223,6 @@  static vm_fault_t dev_dax_huge_fault(str
 		enum page_entry_size pe_size)
 {
 	struct file *filp = vmf->vma->vm_file;
-	unsigned long fault_size;
 	vm_fault_t rc = VM_FAULT_SIGBUS;
 	int id;
 	pfn_t pfn;
@@ -230,23 +235,18 @@  static vm_fault_t dev_dax_huge_fault(str
 	id = dax_read_lock();
 	switch (pe_size) {
 	case PE_SIZE_PTE:
-		fault_size = PAGE_SIZE;
 		rc = __dev_dax_pte_fault(dev_dax, vmf, &pfn);
 		break;
 	case PE_SIZE_PMD:
-		fault_size = PMD_SIZE;
 		rc = __dev_dax_pmd_fault(dev_dax, vmf, &pfn);
 		break;
 	case PE_SIZE_PUD:
-		fault_size = PUD_SIZE;
 		rc = __dev_dax_pud_fault(dev_dax, vmf, &pfn);
 		break;
 	default:
 		rc = VM_FAULT_SIGBUS;
 	}
 
-	if (rc == VM_FAULT_NOPAGE)
-		dax_set_mapping(vmf, pfn, fault_size);
 	dax_read_unlock(id);
 
 	return rc;