linux-kernel - [PATCH v2 07/11] convert this_cpu_cmpxchg users to this_cpu_cmpxchg

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Message-ID: <20230209153204.818774692@redhat.com>
Date:   Thu, 09 Feb 2023 12:01:57 -0300
From:   Marcelo Tosatti <mtosatti@...hat.com>
To:     Christoph Lameter <cl@...ux.com>
Cc:     Aaron Tomlin <atomlin@...mlin.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Marcelo Tosatti <mtosatti@...hat.com>
Subject: [PATCH v2 07/11] convert this_cpu_cmpxchg users to this_cpu_cmpxchg_local

this_cpu_cmpxchg was modified to atomic version, which 
can be more costly than non-atomic version.

Switch users of this_cpu_cmpxchg to this_cpu_cmpxchg_local
(which preserves pre-non-atomic this_cpu_cmpxchg behaviour).

Signed-off-by: Marcelo Tosatti <mtosatti@...hat.com>

Index: linux-vmstat-remote/kernel/fork.c
===================================================================
--- linux-vmstat-remote.orig/kernel/fork.c
+++ linux-vmstat-remote/kernel/fork.c
@@ -203,7 +203,7 @@ static bool try_release_thread_stack_to_
 	unsigned int i;
 
 	for (i = 0; i < NR_CACHED_STACKS; i++) {
-		if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm) != NULL)
+		if (this_cpu_cmpxchg_local(cached_stacks[i], NULL, vm) != NULL)
 			continue;
 		return true;
 	}
Index: linux-vmstat-remote/kernel/scs.c
===================================================================
--- linux-vmstat-remote.orig/kernel/scs.c
+++ linux-vmstat-remote/kernel/scs.c
@@ -79,7 +79,7 @@ void scs_free(void *s)
 	 */
 
 	for (i = 0; i < NR_CACHED_SCS; i++)
-		if (this_cpu_cmpxchg(scs_cache[i], 0, s) == NULL)
+		if (this_cpu_cmpxchg_local(scs_cache[i], 0, s) == NULL)
 			return;
 
 	kasan_unpoison_vmalloc(s, SCS_SIZE, KASAN_VMALLOC_PROT_NORMAL);