hugepage: fix broken check for offset alignment in hugepage mappings

For hugepage mappings, the file offset, like the address and size, needs to
be aligned to the size of a hugepage.

In commit 68589bc353037f233fe510ad9ff432338c95db66, the check for this was
moved into prepare_hugepage_range() along with the address and size checks.
 But since BenH's rework of the get_unmapped_area() paths leading up to
commit 4b1d89290b62bb2db476c94c82cf7442aab440c8, prepare_hugepage_range()
is only called for MAP_FIXED mappings, not for other mappings.  This means
we're no longer ever checking for an aligned offset - I've confirmed that
mmap() will (apparently) succeed with a misaligned offset on both powerpc
and i386 at least.

This patch restores the check, removing it from prepare_hugepage_range()
and putting it back into hugetlbfs_file_mmap().  I'm putting it there,
rather than in the get_unmapped_area() path so it only needs to go in one
place, than separately in the half-dozen or so arch-specific
implementations of hugetlb_get_unmapped_area().

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 4 insertions, 6 deletions

diff --git a/arch/i386/mm/hugetlbpage.c b/arch/i386/mm/hugetlbpage.c
index efdf95ac8031..6c06d9c0488e 100644
--- a/arch/i386/mm/hugetlbpage.c
+++ b/arch/i386/mm/hugetlbpage.c
@@ -367,7 +367,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
                 return -ENOMEM;
 
         if (flags & MAP_FIXED) {
-                if (prepare_hugepage_range(addr, len, pgoff))
+                if (prepare_hugepage_range(addr, len))
                         return -EINVAL;
                 return addr;
         }
diff --git a/arch/ia64/mm/hugetlbpage.c b/arch/ia64/mm/hugetlbpage.c
index d22861c5b04c..a9ff685aea25 100644
--- a/arch/ia64/mm/hugetlbpage.c
+++ b/arch/ia64/mm/hugetlbpage.c
@@ -75,10 +75,8 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
  * Don't actually need to do any preparation, but need to make sure
  * the address is in the right region.
  */
-int prepare_hugepage_range(unsigned long addr, unsigned long len, pgoff_t pgoff)
+int prepare_hugepage_range(unsigned long addr, unsigned long len)
 {
-        if (pgoff & (~HPAGE_MASK >> PAGE_SHIFT))
-                return -EINVAL;
         if (len & ~HPAGE_MASK)
                 return -EINVAL;
         if (addr & ~HPAGE_MASK)
@@ -151,7 +149,7 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr, u
 
         /* Handle MAP_FIXED */
         if (flags & MAP_FIXED) {
-                if (prepare_hugepage_range(addr, len, pgoff))
+                if (prepare_hugepage_range(addr, len))
                         return -EINVAL;
                 return addr;
         }
diff --git a/arch/sparc64/mm/hugetlbpage.c b/arch/sparc64/mm/hugetlbpage.c
index eaba9b70b184..6cfab2e4d340 100644
--- a/arch/sparc64/mm/hugetlbpage.c
+++ b/arch/sparc64/mm/hugetlbpage.c
@@ -175,7 +175,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
                 return -ENOMEM;
 
         if (flags & MAP_FIXED) {
-                if (prepare_hugepage_range(addr, len, pgoff))
+                if (prepare_hugepage_range(addr, len))
                         return -EINVAL;
                 return addr;
         }