hugetlbfs: fix mmap failure in unaligned size request

The current kernel returns -EINVAL unless a given mmap length is
"almost" hugepage aligned.  This is because in sys_mmap_pgoff() the
given length is passed to vm_mmap_pgoff() as it is without being aligned
with hugepage boundary.

This is a regression introduced in commit 40716e29243d ("hugetlbfs: fix
alignment of huge page requests"), where alignment code is pushed into
hugetlb_file_setup() and the variable len in caller side is not changed.

To fix this, this patch partially reverts that commit, and adds
alignment code in caller side.  And it also introduces hstate_sizelog()
in order to get proper hstate to specified hugepage size.

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=56881

[akpm@linux-foundation.org: fix warning when CONFIG_HUGETLB_PAGE=n]
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: <iceman_dvd@yahoo.com>
Cc: Steven Truelove <steven.truelove@utoronto.ca>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 14 deletions

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 523464e6284..a3f868ae3fd 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -909,11 +909,8 @@ static int can_do_hugetlb_shm(void)
 
 static int get_hstate_idx(int page_size_log)
 {
-	struct hstate *h;
+	struct hstate *h = hstate_sizelog(page_size_log);
 
-	if (!page_size_log)
-		return default_hstate_idx;
-	h = size_to_hstate(1 << page_size_log);
 	if (!h)
 		return -1;
 	return h - hstates;
@@ -929,9 +926,12 @@ static struct dentry_operations anon_ops = {
 	.d_dname = hugetlb_dname
 };
 
-struct file *hugetlb_file_setup(const char *name, unsigned long addr,
-				size_t size, vm_flags_t acctflag,
-				struct user_struct **user,
+/*
+ * Note that size should be aligned to proper hugepage size in caller side,
+ * otherwise hugetlb_reserve_pages reserves one less hugepages than intended.
+ */
+struct file *hugetlb_file_setup(const char *name, size_t size,
+				vm_flags_t acctflag, struct user_struct **user,
 				int creat_flags, int page_size_log)
 {
 	struct file *file = ERR_PTR(-ENOMEM);
@@ -939,8 +939,6 @@ struct file *hugetlb_file_setup(const char *name, unsigned long addr,
 	struct path path;
 	struct super_block *sb;
 	struct qstr quick_string;
-	struct hstate *hstate;
-	unsigned long num_pages;
 	int hstate_idx;
 
 	hstate_idx = get_hstate_idx(page_size_log);
@@ -980,12 +978,10 @@ struct file *hugetlb_file_setup(const char *name, unsigned long addr,
 	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);
 	file = ERR_PTR(-ENOMEM);
-	if (hugetlb_reserve_pages(inode, 0, num_pages, NULL, acctflag))
+	if (hugetlb_reserve_pages(inode, 0,
+			size >> huge_page_shift(hstate_inode(inode)), NULL,
+			acctflag))
 		goto out_inode;
 
 	d_instantiate(path.dentry, inode);