On Thu, Apr 20, 2017 at 03:35:09PM +1000, Michael Ellerman wrote:

In crct10dif_vpmsum() we call enable_kernel_altivec() without first
disabling preemption, which is not allowed.

It used to be sufficient just to call pagefault_disable(), because that
also disabled preemption. But the two were decoupled in commit 8222dbe21e79
("sched/preempt, mm/fault: Decouple preemption from the page fault
logic") in mid 2015.

The crct10dif-vpmsum code inherited this bug from the crc32c-vpmsum code
on which it was modelled.

So add the missing preempt_disable/enable(). We should also call
disable_kernel_fp(), although it does nothing by default, there is a
debug switch to make it active and all enables should be paired with
disables.

Fixes: b01df1c16c9a ("crypto: powerpc - Add CRC-T10DIF acceleration")
Acked-by: Daniel Axtens <redacted>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Patch applied.  Thanks.
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