padata: Honor the caller's alignment in case of chunk_size 0

[ Upstream commit 24cc57d8faaa4060fd58adf810b858fcfb71a02f ]

In the case where we are forcing the ps.chunk_size to be at least 1,
we are ignoring the caller's alignment.

Move the forcing of ps.chunk_size to be at least 1 before rounding it
up to caller's alignment, so that caller's alignment is honored.

While at it, use max() to force the ps.chunk_size to be at least 1 to
improve readability.

Fixes: 6d45e1c948a8 ("padata: Fix possible divide-by-0 panic in padata_mt_helper()")
Signed-off-by: Kamlesh Gurudasani <kamlesh@ti.com>
Acked-by:  Waiman Long <longman@redhat.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/padata.c b/kernel/padata.c
index 2a514cf8379b4477527601c4d01052cbff17f31b..41d5bf2fa2ad99449f93fefd989531c53f350e39 100644 (file)
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -516,9 +516,12 @@ void __init padata_do_multithreaded(struct padata_mt_job *job)
         * thread function.  Load balance large jobs between threads by
         * increasing the number of chunks, guarantee at least the minimum
         * chunk size from the caller, and honor the caller's alignment.
+        * Ensure chunk_size is at least 1 to prevent divide-by-0
+        * panic in padata_mt_helper().
         */
        ps.chunk_size = job->size / (ps.nworks * load_balance_factor);
        ps.chunk_size = max(ps.chunk_size, job->min_chunk);
+       ps.chunk_size = max(ps.chunk_size, 1ul);
        ps.chunk_size = roundup(ps.chunk_size, job->align);
 
        /*