With additional debugging enabled, seeing warnings for suspicious RCU
usage or Sleeping function called from invalid context.

These both map to allocation of a work structure which is currently
GFP_KERNEL, meaning it can sleep. For the RCU warning, the sequence was
sleeping while holding the RCU lock.

Convert the allocation to GFP_ATOMIC.
Signed-off-by: James Smart <jsmart2021@gmail.com>
Reviewed-by: Minwoo Im <minwoo.im.dev@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>