mm, x86, pat: rework linear pfn-mmap tracking

Replace the generic vma-flag VM_PFN_AT_MMAP with x86-only VM_PAT.

We can toss mapping address from remap_pfn_range() into
track_pfn_vma_new(), and collect all PAT-related logic together in
arch/x86/.

This patch also restores orignal frustration-free is_cow_mapping() check
in remap_pfn_range(), as it was before commit v2.6.28-rc8-88-g3c8bb73
("x86: PAT: store vm_pgoff for all linear_over_vma_region mappings - v3")

is_linear_pfn_mapping() checks can be removed from mm/huge_memory.c,
because it already handled by VM_PFNMAP in VM_NO_THP bit-mask.

[suresh.b.siddha@intel.com: Reset the VM_PAT flag as part of untrack_pfn_vma()]
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Venkatesh Pallipadi <venki@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Carsten Otte <cotte@de.ibm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Kentaro Takeda <takedakn@nttdata.co.jp>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Venkatesh Pallipadi <venki@google.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 5 deletions

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 74a702674e86..0eb572eda406 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -677,7 +677,7 @@ int track_pfn_copy(struct vm_area_struct *vma)
         unsigned long vma_size = vma->vm_end - vma->vm_start;
         pgprot_t pgprot;
 
-        if (is_linear_pfn_mapping(vma)) {
+        if (vma->vm_flags & VM_PAT) {
                 /*
                  * reserve the whole chunk covered by vma. We need the
                  * starting address and protection from pte.
@@ -699,14 +699,20 @@ int track_pfn_copy(struct vm_area_struct *vma)
  * single reserve_pfn_range call.
  */
 int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
-                    unsigned long pfn, unsigned long size)
+                    unsigned long pfn, unsigned long addr, unsigned long size)
 {
         resource_size_t paddr = (resource_size_t)pfn << PAGE_SHIFT;
         unsigned long flags;
 
         /* reserve the whole chunk starting from paddr */
-        if (is_linear_pfn_mapping(vma))
-                return reserve_pfn_range(paddr, size, prot, 0);
+        if (addr == vma->vm_start && size == (vma->vm_end - vma->vm_start)) {
+                int ret;
+
+                ret = reserve_pfn_range(paddr, size, prot, 0);
+                if (!ret)
+                        vma->vm_flags |= VM_PAT;
+                return ret;
+        }
 
         if (!pat_enabled)
                 return 0;
@@ -758,7 +764,7 @@ void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn,
         resource_size_t paddr;
         unsigned long prot;
 
-        if (!is_linear_pfn_mapping(vma))
+        if (!(vma->vm_flags & VM_PAT))
                 return;
 
         /* free the chunk starting from pfn or the whole chunk */
@@ -772,6 +778,7 @@ void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn,
                 size = vma->vm_end - vma->vm_start;
         }
         free_pfn_range(paddr, size);
+        vma->vm_flags &= ~VM_PAT;
 }
 
 pgprot_t pgprot_writecombine(pgprot_t prot)