The patch titled Subject: padata: honor the caller's alignment in case of chunk_size 0 has been added to the -mm mm-hotfixes-unstable branch. Its filename is padata-honor-the-callers-alignment-in-case-of-chunk_size-0.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Kamlesh Gurudasani kamlesh@ti.com Subject: padata: honor the caller's alignment in case of chunk_size 0 Date: Thu, 22 Aug 2024 02:32:52 +0530

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.

Link: https://lkml.kernel.org/r/20240822-max-v1-1-cb4bc5b1c101@ti.com Fixes: 6d45e1c948a8 ("padata: Fix possible divide-by-0 panic in padata_mt_helper()") Signed-off-by: Kamlesh Gurudasani kamlesh@ti.com Cc: Daniel Jordan daniel.m.jordan@oracle.com Cc: Herbert Xu herbert@gondor.apana.org.au Cc: Steffen Klassert steffen.klassert@secunet.com Cc: Waiman Long longman@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

kernel/padata.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-)

--- a/kernel/padata.c~padata-honor-the-callers-alignment-in-case-of-chunk_size-0 +++ a/kernel/padata.c @@ -509,21 +509,17 @@ void __init padata_do_multithreaded(stru

/* * Chunk size is the amount of work a helper does per call to the - * thread function. Load balance large jobs between threads by + * 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);

- /* - * chunk_size can be 0 if the caller sets min_chunk to 0. So force it - * to at least 1 to prevent divide-by-0 panic in padata_mt_helper().` - */ - if (!ps.chunk_size) - ps.chunk_size = 1U; - list_for_each_entry(pw, &works, pw_list) if (job->numa_aware) { int old_node = atomic_read(&last_used_nid); _

Patches currently in -mm which might be from kamlesh@ti.com are

padata-honor-the-callers-alignment-in-case-of-chunk_size-0.patch