From: Yajun Deng <yajun.deng@linux.dev>
To: gregkh@linuxfoundation.org, rafael@kernel.org, rppt@kernel.org,
akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Yajun Deng <yajun.deng@linux.dev>
Subject: [PATCH] mm/mm_init.c: remove spinlock in early_pfn_to_nid()
Date: Wed, 14 Jun 2023 19:03:24 +0800 [thread overview]
Message-ID: <20230614110324.3839354-1-yajun.deng@linux.dev> (raw)
When the system boots, only one cpu is enabled before smp_init().
So the spinlock is not needed in most cases, remove it.
Add spinlock in get_nid_for_pfn() because it is after smp_init().
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
---
drivers/base/node.c | 11 +++++++++--
mm/mm_init.c | 18 +++---------------
2 files changed, 12 insertions(+), 17 deletions(-)
diff --git a/drivers/base/node.c b/drivers/base/node.c
index 9de524e56307..844102570ff2 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -748,8 +748,15 @@ int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)
static int __ref get_nid_for_pfn(unsigned long pfn)
{
#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
- if (system_state < SYSTEM_RUNNING)
- return early_pfn_to_nid(pfn);
+ static DEFINE_SPINLOCK(early_pfn_lock);
+ int nid;
+
+ if (system_state < SYSTEM_RUNNING) {
+ spin_lock(&early_pfn_lock);
+ nid = early_pfn_to_nid(pfn);
+ spin_unlock(&early_pfn_lock);
+ return nid;
+ }
#endif
return pfn_to_nid(pfn);
}
diff --git a/mm/mm_init.c b/mm/mm_init.c
index d393631599a7..5895a30435ee 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -584,11 +584,11 @@ struct mminit_pfnnid_cache {
static struct mminit_pfnnid_cache early_pfnnid_cache __meminitdata;
/*
- * Required by SPARSEMEM. Given a PFN, return what node the PFN is on.
+ * Given a PFN, return what node the PFN is on.
*/
-static int __meminit __early_pfn_to_nid(unsigned long pfn,
- struct mminit_pfnnid_cache *state)
+int __meminit early_pfn_to_nid(unsigned long pfn)
{
+ struct mminit_pfnnid_cache *state = &early_pfnnid_cache;
unsigned long start_pfn, end_pfn;
int nid;
@@ -601,20 +601,8 @@ static int __meminit __early_pfn_to_nid(unsigned long pfn,
state->last_end = end_pfn;
state->last_nid = nid;
}
-
- return nid;
-}
-
-int __meminit early_pfn_to_nid(unsigned long pfn)
-{
- static DEFINE_SPINLOCK(early_pfn_lock);
- int nid;
-
- spin_lock(&early_pfn_lock);
- nid = __early_pfn_to_nid(pfn, &early_pfnnid_cache);
if (nid < 0)
nid = first_online_node;
- spin_unlock(&early_pfn_lock);
return nid;
}
--
2.25.1
next reply other threads:[~2023-06-14 11:04 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-14 11:03 Yajun Deng [this message]
2023-06-14 11:09 ` [PATCH] mm/mm_init.c: remove spinlock in early_pfn_to_nid() Greg KH
2023-06-14 11:28 ` Yajun Deng
2023-06-14 11:53 ` Mike Rapoport
2023-06-15 3:02 ` Yajun Deng
2023-06-15 6:20 ` Mike Rapoport
2023-06-15 6:36 ` Yajun Deng
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