padata: use alignment when calculating the number of worker threads

For multithreaded jobs the computed chunk size is rounded up by the
caller-specified alignment. However, the number of worker threads to
use is computed using the minimum chunk size without taking alignment
into account. A sufficiently large alignment value can result in too
many worker threads being allocated for the job.

Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

kernel/padata.c

@@ -491,7 +491,7 @@ void __init padata_do_multithreaded(struct padata_mt_job *job)
 		return;
 
 	/* Ensure at least one thread when size < min_chunk. */
-	nworks = max(job->size / job->min_chunk, 1ul);
+	nworks = max(job->size / max(job->min_chunk, job->align), 1ul);
 	nworks = min(nworks, job->max_threads);
 
 	if (nworks == 1) {