[SCSI] sg: Free data buffers after calling blk_rq_unmap_user
Running sg_luns on s390x with CONFIG_DEBUG_PAGEALLOC enabled fails
with EFAULT from the SG_IO ioctl. The EFAULT is the result from
copy_to_user failing in this call chain:
The sg driver calls sg_remove_scat to free the memory pages before
calling blk_rq_unmap_user that tries to copy the data back to
userspace. Change the order to first call blk_rq_unmap_user before
freeing the pages in sg_remove_scat.
Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: stable@kernel.org Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com> Acked-by: Douglas Gilbert <dgilbert@interlog.com> Signed-off-by: James Bottomley <James.Bottomley@suse.de>