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/padata-honor-the-callers-alignment-in-case-of-chunk_size-0.patch
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@xxxxxx>
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@xxxxxx
Fixes: 6d45e1c948a8 ("padata: Fix possible divide-by-0 panic in padata_mt_helper()")
Signed-off-by: Kamlesh Gurudasani <kamlesh@xxxxxx>
Cc: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Cc: Waiman Long <longman@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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@xxxxxx are
padata-honor-the-callers-alignment-in-case-of-chunk_size-0.patch
