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Christof Schmitt authored
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: sg_ioctl sg_new_read sg_finish_rem_req blk_rq_unmap_user __blk_rq_unmap_user bio_uncopy_user __bio_copy_iov copy_to_user 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>
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