From: John Hubbard jhubbard@nvidia.com
For pages that were retained via get_user_pages*(), release those pages via the new put_user_page*() routines, instead of via put_page() or release_pages().
This is part a tree-wide conversion, as described in commit fc1d8e7cca2d ("mm: introduce put_user_page*(), placeholder versions").
This also handles pages[i] == NULL cases, thanks to an approach that is actually written by Juergen Gross.
Signed-off-by: Juergen Gross jgross@suse.com Signed-off-by: John Hubbard jhubbard@nvidia.com
Cc: Boris Ostrovsky boris.ostrovsky@oracle.com Cc: xen-devel@lists.xenproject.org ---
Hi Juergen,
Say, this is *exactly* what you proposed in your gup.patch, so I've speculatively added your Signed-off-by above, but need your approval before that's final. Let me know please...
thanks, John Hubbard
drivers/xen/privcmd.c | 32 +++++++++++--------------------- 1 file changed, 11 insertions(+), 21 deletions(-)
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c index c6070e70dd73..c7d0763ca8c2 100644 --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -582,10 +582,11 @@ static long privcmd_ioctl_mmap_batch(
static int lock_pages( struct privcmd_dm_op_buf kbufs[], unsigned int num, - struct page *pages[], unsigned int nr_pages) + struct page *pages[], unsigned int *nr_pages) { - unsigned int i; + unsigned int i, free = *nr_pages;
+ *nr_pages = 0; for (i = 0; i < num; i++) { unsigned int requested; int pinned; @@ -593,35 +594,22 @@ static int lock_pages( requested = DIV_ROUND_UP( offset_in_page(kbufs[i].uptr) + kbufs[i].size, PAGE_SIZE); - if (requested > nr_pages) + if (requested > free) return -ENOSPC;
pinned = get_user_pages_fast( (unsigned long) kbufs[i].uptr, - requested, FOLL_WRITE, pages); + requested, FOLL_WRITE, pages + *nr_pages); if (pinned < 0) return pinned;
- nr_pages -= pinned; - pages += pinned; + free -= pinned; + *nr_pages += pinned; }
return 0; }
-static void unlock_pages(struct page *pages[], unsigned int nr_pages) -{ - unsigned int i; - - if (!pages) - return; - - for (i = 0; i < nr_pages; i++) { - if (pages[i]) - put_page(pages[i]); - } -} - static long privcmd_ioctl_dm_op(struct file *file, void __user *udata) { struct privcmd_data *data = file->private_data; @@ -681,11 +669,12 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
xbufs = kcalloc(kdata.num, sizeof(*xbufs), GFP_KERNEL); if (!xbufs) { + nr_pages = 0; rc = -ENOMEM; goto out; }
- rc = lock_pages(kbufs, kdata.num, pages, nr_pages); + rc = lock_pages(kbufs, kdata.num, pages, &nr_pages); if (rc) goto out;
@@ -699,7 +688,8 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata) xen_preemptible_hcall_end();
out: - unlock_pages(pages, nr_pages); + if (pages) + put_user_pages(pages, nr_pages); kfree(xbufs); kfree(pages); kfree(kbufs);