This is a note to let you know that I've just added the patch titled
padata: Honor the caller's alignment in case of chunk_size 0
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
padata-honor-the-caller-s-alignment-in-case-of-chunk.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 0c70f9d8876152e407cb87b421c52b5348f194b0
Author: Kamlesh Gurudasani <kamlesh@xxxxxx>
Date: Thu Aug 22 02:32:52 2024 +0530
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@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>
diff --git a/kernel/padata.c b/kernel/padata.c
index 29545dd6dd53d..da788a58d19cf 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -511,9 +511,12 @@ 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);
/*
