+ padata-downgrade-padata_do_multithreaded-to-serial-execution-for-non-smp.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: padata: downgrade padata_do_multithreaded to serial execution for non-SMP
has been added to the -mm mm-unstable branch.  Its filename is
     padata-downgrade-padata_do_multithreaded-to-serial-execution-for-non-smp.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/padata-downgrade-padata_do_multithreaded-to-serial-execution-for-non-smp.patch

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

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------------------------------------------------------
From: Gang Li <gang.li@linux.dev>
Subject: padata: downgrade padata_do_multithreaded to serial execution for non-SMP
Date: Thu, 22 Feb 2024 22:04:18 +0800

hugetlb parallelization depends on PADATA, and PADATA depends on SMP.

PADATA consists of two distinct functionality: One part is
padata_do_multithreaded which disregards order and simply divides tasks
into several groups for parallel execution.  Hugetlb init parallelization
depends on padata_do_multithreaded.

The other part is composed of a set of APIs that, while handling data in
an out-of-order parallel manner, can eventually return the data with
ordered sequence.  Currently Only `crypto/pcrypt.c` use them.

All users of PADATA of non-SMP case currently only use
padata_do_multithreaded.  It is easy to implement a serial one in
include/linux/padata.h.  And it is not necessary to implement another
functionality unless the only user of crypto/pcrypt.c does not depend on
SMP in the future.

Link: https://lkml.kernel.org/r/20240222140422.393911-6-gang.li@linux.dev
Signed-off-by: Gang Li <ligang.bdlg@bytedance.com>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/padata.h |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--- a/include/linux/padata.h~padata-downgrade-padata_do_multithreaded-to-serial-execution-for-non-smp
+++ a/include/linux/padata.h
@@ -180,10 +180,6 @@ struct padata_instance {
 
 #ifdef CONFIG_PADATA
 extern void __init padata_init(void);
-#else
-static inline void __init padata_init(void) {}
-#endif
-
 extern struct padata_instance *padata_alloc(const char *name);
 extern void padata_free(struct padata_instance *pinst);
 extern struct padata_shell *padata_alloc_shell(struct padata_instance *pinst);
@@ -194,4 +190,12 @@ extern void padata_do_serial(struct pada
 extern void __init padata_do_multithreaded(struct padata_mt_job *job);
 extern int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
 			      cpumask_var_t cpumask);
+#else
+static inline void __init padata_init(void) {}
+static inline void __init padata_do_multithreaded(struct padata_mt_job *job)
+{
+	job->thread_fn(job->start, job->start + job->size, job->fn_arg);
+}
+#endif
+
 #endif
_

Patches currently in -mm which might be from gang.li@linux.dev are

hugetlb-code-clean-for-hugetlb_hstate_alloc_pages.patch
hugetlb-split-hugetlb_hstate_alloc_pages.patch
hugetlb-pass-next_nid_to_alloc-directly-to-for_each_node_mask_to_alloc.patch
padata-dispatch-works-on-different-nodes.patch
padata-downgrade-padata_do_multithreaded-to-serial-execution-for-non-smp.patch
hugetlb-have-config_hugetlbfs-select-config_padata.patch
hugetlb-parallelize-2m-hugetlb-allocation-and-initialization.patch
hugetlb-parallelize-1g-hugetlb-initialization.patch