[PATCH 3.8 72/81] ALSA: us122l: Fix pcm_usb_stream mmapping regression

From: Kamal Mostafa
Date: Tue Oct 29 2013 - 14:08:13 EST -stable review patch. If anyone has any objections, please let me know.


From: Takashi Iwai <tiwai@xxxxxxx>

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@xxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
sound/usb/usx2y/us122l.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sound/usb/usx2y/us122l.c b/sound/usb/usx2y/us122l.c
index d0323a6..999550b 100644
--- a/sound/usb/usx2y/us122l.c
+++ b/sound/usb/usx2y/us122l.c
@@ -262,7 +262,9 @@ static int usb_stream_hwdep_mmap(struct snd_hwdep *hw,

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;

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