Hi Dennis,

I love your patch! Yet something to improve:

[auto build test ERROR on kdave/for-next]
[cannot apply to v5.4-rc8 next-20191122]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Dennis-Zhou/btrfs-async-discard-support/20191121-230429
base:   https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next
config: arm-allmodconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (GCC) 7.4.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.4.0 make.cross ARCH=arm 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> ERROR: "__aeabi_uldivmod" [fs/btrfs/btrfs.ko] undefined!

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0-DAY kernel test infrastructure                 Open Source Technology Center
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