ALSA: usx2y: Suppress kernel warning at page allocation failures

BugLink: http://bugs.launchpad.net/bugs/1723145
commit 7682e399485fe19622b6fd82510b1f4551e48a25 upstream.

The usx2y driver allocates the stream read/write buffers in continuous
pages depending on the stream setup, and this may spew the kernel
warning messages with a stack trace like:
  WARNING: CPU: 1 PID: 1846 at mm/page_alloc.c:3883
  __alloc_pages_slowpath+0x1ef2/0x2d70
  Modules linked in:
  CPU: 1 PID: 1846 Comm: kworker/1:2 Not tainted
  ....

It may confuse user as if it were any serious error, although this is
no fatal error and the driver handles the error case gracefully.
Since the driver has already some sanity check of the given size (128
and 256 pages), it can't pass any crazy value.  So it's merely page
fragmentation.

This patch adds __GFP_NOWARN to each caller for suppressing such
kernel warnings.  The original issue was spotted by syzkaller.

Reported-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/sound/usb/usx2y/usb_stream.c b/sound/usb/usx2y/usb_stream.c
index bf618e1500acb3488193b90e6e7dc4469e22509d..e7b934f4d837ba7f2a6d7d502288cb5aca5465eb 100644 (file)
--- a/sound/usb/usx2y/usb_stream.c
+++ b/sound/usb/usx2y/usb_stream.c
@@ -191,7 +191,8 @@ struct usb_stream *usb_stream_new(struct usb_stream_kernel *sk,
        }
 
        pg = get_order(read_size);
-       sk->s = (void *) __get_free_pages(GFP_KERNEL|__GFP_COMP|__GFP_ZERO, pg);
+       sk->s = (void *) __get_free_pages(GFP_KERNEL|__GFP_COMP|__GFP_ZERO|
+                                         __GFP_NOWARN, pg);
        if (!sk->s) {
                snd_printk(KERN_WARNING "couldn't __get_free_pages()\n");
                goto out;
@@ -211,7 +212,8 @@ struct usb_stream *usb_stream_new(struct usb_stream_kernel *sk,
        pg = get_order(write_size);
 
        sk->write_page =
-               (void *)__get_free_pages(GFP_KERNEL|__GFP_COMP|__GFP_ZERO, pg);
+               (void *)__get_free_pages(GFP_KERNEL|__GFP_COMP|__GFP_ZERO|
+                                        __GFP_NOWARN, pg);
        if (!sk->write_page) {
                snd_printk(KERN_WARNING "couldn't __get_free_pages()\n");
                usb_stream_free(sk);