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commit11e63f6d92upstream. Before we rework the "pmem api" to stop abusing __copy_user_nocache() for memcpy_to_pmem() we need to fix cases where we may strand dirty data in the cpu cache. The problem occurs when copy_from_iter_pmem() is used for arbitrary data transfers from userspace. There is no guarantee that these transfers, performed by dax_iomap_actor(), will have aligned destinations or aligned transfer lengths. Backstop the usage __copy_user_nocache() with explicit cache management in these unaligned cases. Yes, copy_from_iter_pmem() is now too big for an inline, but addressing that is saved for a later patch that moves the entirety of the "pmem api" into the pmem driver directly. Fixes:5de490daec("pmem: add copy_from_iter_pmem() and clear_pmem()") Cc: <x86@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Matthew Wilcox <mawilcox@microsoft.com> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Toshi Kani <toshi.kani@hpe.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>