5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kamlesh Gurudasani <kamlesh@xxxxxx>
[ 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@xxxxxx>
Acked-by: Waiman Long <longman@xxxxxxxxxx>
Acked-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
kernel/padata.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/padata.c b/kernel/padata.c
index 7c52f9de5d4ec..f567b54d79639 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -503,9 +503,12 @@ 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);
/*
--
2.43.0
