Re: WARNING in __alloc_pages_nodemask

[Matthew Wilcox]

On Mon, Sep 16, 2019 at 01:00:11PM -0700, David Rientjes wrote:
> On Mon, 16 Sep 2019, syzbot wrote:
> > HEAD commit:    f0df5c1b usb-fuzzer: main usb gadget fuzzer driver
> > git tree:       https://github.com/google/kasan.git usb-fuzzer
> > console output: https://syzkaller.appspot.com/x/log.txt?x=14b15371600000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=5c6633fa4ed00be5
> > dashboard link: https://syzkaller.appspot.com/bug?extid=e38fe539fedfc127987e
> > compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1093bed1600000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1603cfc6600000
> > 
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+e38fe539fedfc127987e@xxxxxxxxxxxxxxxxxxxxxxxxx
> > 
> > WARNING: CPU: 0 PID: 1720 at mm/page_alloc.c:4696
> > __alloc_pages_nodemask+0x36f/0x780 mm/page_alloc.c:4696
> > Kernel panic - not syncing: panic_on_warn set ...

> > alloc_pages_current+0xff/0x200 mm/mempolicy.c:2153
> > alloc_pages include/linux/gfp.h:509 [inline]
> > kmalloc_order+0x1a/0x60 mm/slab_common.c:1257
> > kmalloc_order_trace+0x18/0x110 mm/slab_common.c:1269
> > __usbhid_submit_report drivers/hid/usbhid/hid-core.c:588 [inline]
> > usbhid_submit_report+0x5b5/0xde0 drivers/hid/usbhid/hid-core.c:638
> > usbhid_request+0x3c/0x70 drivers/hid/usbhid/hid-core.c:1252
> > hid_hw_request include/linux/hid.h:1053 [inline]
> > hiddev_ioctl+0x526/0x1550 drivers/hid/usbhid/hiddev.c:735
> Adding Jiri and Benjamin.  The hid report length is simply too large for 
> the page allocator to allocate: this is triggering because the resulting 
> allocation order is > MAX_ORDER-1.  Any way to make this allocate less 
> physically contiguous memory?

The HID code should, presumably, reject reports which are larger than
PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER.  Particularly since it's using
GFP_ATOMIC.