On Mon, 27 Feb 2012 09:09:28 -0500
Steven Truelove<steven.truelove@xxxxxxxxxxx> wrote:
When calling shmget with SHM_HUGETLB, shmget aligns the request size to PAGE_SIZE, but this is not sufficient. Modified hugetlb_file_setup to align requests to the huge page size.A few things...
Signed-off-by: Steven Truelove<steven.truelove@xxxxxxxxxxx>
---
fs/hugetlbfs/inode.c | 9 ++++++---
1 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 1e85a7a..6c23f09 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -938,6 +938,8 @@ struct file *hugetlb_file_setup(const char *name, size_t size,
struct path path;
struct dentry *root;
struct qstr quick_string;
+ struct hstate *hstate;
+ int num_pages;
*user = NULL;
if (!hugetlbfs_vfsmount)
@@ -967,10 +969,11 @@ struct file *hugetlb_file_setup(const char *name, size_t size,
if (!inode)
goto out_dentry;
+ hstate = hstate_inode(inode);
+ num_pages = (size + huge_page_size(hstate) - 1)>>
+ 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);
- sys_mmap_pgoff() does the rounding up prior to calling
hugetlb_file_setup(). ipc/shm.c:newseg() does not.
We should be consistent here: do it in the caller or the callee,
not both (or neither!). I guess doing it in the callee would be
best.
- The above code could/should have used ALIGN(). Or round_up(): the
difference presently escapes me, even though it was so obvious that
we left all these things undocumented.
- What's the point in aligning the length if we don't also look at
the start address? If that isn't a multiple of huge_page_size(), we
will need an additional page.