This is a note to let you know that I've just added the patch titled usb: devio, do not warn when allocation fails to the 4.7-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: usb-devio-do-not-warn-when-allocation-fails.patch and it can be found in the queue-4.7 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 70f7ca9a0262784d0b80727860a63d64ab228e7b Mon Sep 17 00:00:00 2001 From: Jiri Slaby <jslaby@xxxxxxx> Date: Wed, 15 Jun 2016 15:56:11 +0200 Subject: usb: devio, do not warn when allocation fails From: Jiri Slaby <jslaby@xxxxxxx> commit 70f7ca9a0262784d0b80727860a63d64ab228e7b upstream. usbdev_mmap allocates a buffer. The size of the buffer is determined by a user. So with this code (no need to be root): int fd = open("/dev/bus/usb/001/001", O_RDONLY); mmap(NULL, 0x800000, PROT_READ, MAP_SHARED, fd, 0); we can see a warning: WARNING: CPU: 0 PID: 21771 at ../mm/page_alloc.c:3563 __alloc_pages_slowpath+0x1036/0x16e0() ... Call Trace: [<ffffffff8117a3ae>] ? warn_slowpath_null+0x2e/0x40 [<ffffffff815178b6>] ? __alloc_pages_slowpath+0x1036/0x16e0 [<ffffffff81516880>] ? warn_alloc_failed+0x250/0x250 [<ffffffff8151226b>] ? get_page_from_freelist+0x75b/0x28b0 [<ffffffff815184e3>] ? __alloc_pages_nodemask+0x583/0x6b0 [<ffffffff81517f60>] ? __alloc_pages_slowpath+0x16e0/0x16e0 [<ffffffff810565d4>] ? dma_generic_alloc_coherent+0x104/0x220 [<ffffffffa0269e56>] ? hcd_buffer_alloc+0x1d6/0x3e0 [usbcore] [<ffffffffa0269c80>] ? hcd_buffer_destroy+0xa0/0xa0 [usbcore] [<ffffffffa0228f05>] ? usb_alloc_coherent+0x65/0x90 [usbcore] [<ffffffffa0275c05>] ? usbdev_mmap+0x1a5/0x770 [usbcore] ... Allocations like this one should be marked as __GFP_NOWARN. So do so. The size could be also clipped by something like: if (size >= (1 << (MAX_ORDER + PAGE_SHIFT - 1))) return -ENOMEM; But I think the overall limit of 16M (by usbfs_increase_memory_usage) is enough, so that we only silence the warning here. Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Cc: Steinar H. Gunderson <sesse@xxxxxxxxxx> Cc: Markus Rechberger <mrechberger@xxxxxxxxx> Fixes: f7d34b445a (USB: Add support for usbfs zerocopy.) Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/core/devio.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -241,7 +241,8 @@ static int usbdev_mmap(struct file *file goto error_decrease_mem; } - mem = usb_alloc_coherent(ps->dev, size, GFP_USER, &dma_handle); + mem = usb_alloc_coherent(ps->dev, size, GFP_USER | __GFP_NOWARN, + &dma_handle); if (!mem) { ret = -ENOMEM; goto error_free_usbm; Patches currently in stable-queue which might be from jslaby@xxxxxxx are queue-4.7/usb-devio-do-not-warn-when-allocation-fails.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html