hugetlbfs: fix alignment of huge page requests

When calling shmget() with SHM_HUGETLB, shmget aligns the request size to
PAGE_SIZE, but this is not sufficient.

Modify hugetlb_file_setup() to align requests to the huge page size, and
to accept an address argument so that all alignment checks can be
performed in hugetlb_file_setup(), rather than in its callers.  Change
newseg() and mmap_pgoff() to match the new prototype and eliminate a now
redundant alignment check.

[akpm@linux-foundation.org: fix build]
Signed-off-by: Steven Truelove <steven.truelove@utoronto.ca>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 5 deletions

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 79408159a001..631329f3de63 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -935,8 +935,8 @@ static int can_do_hugetlb_shm(void)
         return capable(CAP_IPC_LOCK) || in_group_p(sysctl_hugetlb_shm_group);
 }
 
-struct file *hugetlb_file_setup(const char *name, size_t size,
-                                vm_flags_t acctflag,
+struct file *hugetlb_file_setup(const char *name, unsigned long addr,
+                                size_t size, vm_flags_t acctflag,
                                 struct user_struct **user, int creat_flags)
 {
         int error = -ENOMEM;
@@ -945,6 +945,8 @@ struct file *hugetlb_file_setup(const char *name, size_t size,
         struct path path;
         struct dentry *root;
         struct qstr quick_string;
+        struct hstate *hstate;
+        unsigned long num_pages;
 
         *user = NULL;
         if (!hugetlbfs_vfsmount)
@@ -978,10 +980,12 @@ struct file *hugetlb_file_setup(const char *name, size_t size,
         if (!inode)
                 goto out_dentry;
 
+        hstate = hstate_inode(inode);
+        size += addr & ~huge_page_mask(hstate);
+        num_pages = ALIGN(size, huge_page_size(hstate)) >>
+                        huge_page_shift(hstate);
         error = -ENOMEM;
-        if (hugetlb_reserve_pages(inode, 0,
-                        size >> huge_page_shift(hstate_inode(inode)), NULL,
-                        acctflag))
+        if (hugetlb_reserve_pages(inode, 0, num_pages, NULL, acctflag))
                 goto out_inode;
 
         d_instantiate(path.dentry, inode);