[PATCH 4/5] mm: fix cache mode of dax pmd mappings

Dan Williams
2016-09-06T16:53:19Z

track_pfn_insert() is marking dax mappings as uncacheable.

It is used to keep mappings attributes consistent across a remapped range.
However, since dax regions are never registered via track_pfn_remap(), the
caching mode lookup for dax pfns always returns _PAGE_CACHE_MODE_UC. We do not
use track_pfn_insert() in the dax-pte path, and we always want to use the
pgprot of the vma itself, so drop this call.

Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nilesh Choudhury <nilesh.choudhury@oracle.com>
Reported-by: Kai Zhang <kai.ka.zhang@oracle.com>
Reported-by: Toshi Kani <toshi.kani@hpe.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
mm/huge_memory.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index a6abd76baa72..338eff05c77a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -676,8 +676,6 @@ int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,

if (addr < vma->vm_start || addr >= vma->vm_end)
return VM_FAULT_SIGBUS;
- if (track_pfn_insert(vma, &pgprot, pfn))
- return VM_FAULT_SIGBUS;
insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write);
return VM_FAULT_NOPAGE;
}