[PATCH 3.10 47/54] ALSA: us122l: Fix pcm_usb_stream mmapping regression

Greg Kroah-Hartman
2013-11-01T22:05:22Z

From: Takashi Iwai <tiwai@suse.de>

commit ac536a848a1643e4b87e8fbd376a63091afc2ccc upstream.

The pcm_usb_stream plugin requires the mremap explicitly for the read
buffer, as it expands itself once after reading the required size.
But the commit [314e51b9: mm: kill vma flag VM_RESERVED and
mm->reserved_vm counter] converted blindly to a combination of
VM_DONTEXPAND | VM_DONTDUMP like other normal drivers, and this
resulted in the failure of mremap().

For fixing this regression, we need to remove VM_DONTEXPAND for the
read-buffer mmap.

Reported-and-tested-by: James Miller <jamesstewartmiller@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
sound/usb/usx2y/us122l.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/sound/usb/usx2y/us122l.c
+++ b/sound/usb/usx2y/us122l.c
@@ -262,7 +262,9 @@ static int usb_stream_hwdep_mmap(struct
}

area->vm_ops = &usb_stream_hwdep_vm_ops;
- area->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
+ area->vm_flags |= VM_DONTDUMP;
+ if (!read)
+ area->vm_flags |= VM_DONTEXPAND;
area->vm_private_data = us122l;
atomic_inc(&us122l->mmap_count);