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>

1 files changed, 3 insertions, 7 deletions

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index e6a71c82d204..3a19b032c0eb 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -66,11 +66,8 @@ void hugetlb_free_pgd_range(struct mmu_gather **tlb, unsigned long addr,
  * If the arch doesn't supply something else, assume that hugepage
  * size aligned regions are ok without further preparation.
  */
-static inline int prepare_hugepage_range(unsigned long addr, unsigned long len,
-                                                pgoff_t pgoff)
+static inline 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)
@@ -78,8 +75,7 @@ static inline int prepare_hugepage_range(unsigned long addr, unsigned long len,
         return 0;
 }
 #else
-int prepare_hugepage_range(unsigned long addr, unsigned long len,
-                                                pgoff_t pgoff);
+int prepare_hugepage_range(unsigned long addr, unsigned long len);
 #endif
 
 #ifndef ARCH_HAS_SETCLEAR_HUGE_PTE
@@ -117,7 +113,7 @@ static inline unsigned long hugetlb_total_pages(void)
 #define hugetlb_report_meminfo(buf)             0
 #define hugetlb_report_node_meminfo(n, buf)     0
 #define follow_huge_pmd(mm, addr, pmd, write)   NULL
-#define prepare_hugepage_range(addr,len,pgoff)  (-EINVAL)
+#define prepare_hugepage_range(addr,len)        (-EINVAL)
 #define pmd_huge(x)     0
 #define is_hugepage_only_range(mm, addr, len)   0
 #define hugetlb_free_pgd_range(tlb, addr, end, floor, ceiling) ({BUG(); 0; })