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Date: Wed, 14 Sep 2022 15:26:03 +0800
From: Muchun Song <songmuchun@...edance.com>
To: gregkh@...uxfoundation.org, rafael@...nel.org,
mike.kravetz@...cle.com, songmuchun@...edance.com,
akpm@...ux-foundation.org, osalvador@...e.de, david@...hat.com,
ying.huang@...el.com, aneesh.kumar@...ux.ibm.com,
rientjes@...gle.com
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
muchun.song@...ux.dev
Subject: [PATCH v4 2/2] mm: hugetlb: eliminate memory-less nodes handling
The memory-notify-based approach aims to handle meory-less nodes, however, it just adds
the complexity of code as pointed by David in thread [1]. The handling of memory-less
nodes is introduced by commit 4faf8d950ec4 ("hugetlb: handle memory hot-plug events").
>From its commit message, we cannot find any necessity of handling this case. So, we can
simply register/unregister sysfs entries in register_node/unregister_node to simlify the
code.
BTW, hotplug callback added because in hugetlb_register_all_nodes() we register sysfs
nodes only for N_MEMORY nodes, seeing commit 9b5e5d0fdc91, which said it was a preparation
for handling memory-less nodes via memory hotplug. Since we want to remove memory hotplug,
so make sure we only register per-node sysfs for online (N_ONLINE) nodes in
hugetlb_register_all_nodes().
https://lore.kernel.org/linux-mm/60933ffc-b850-976c-78a0-0ee6e0ea9ef0@redhat.com/ [1]
Suggested-by: David Hildenbrand <david@...hat.com>
Signed-off-by: Muchun Song <songmuchun@...edance.com>
Acked-by: David Hildenbrand <david@...hat.com>
---
v4:
- Remove hugetlb_mark_sysfs_initialized() helper per David.
v3:
- Fix 'struct node' is not declared reported by LTP.
v2:
- Move declaration of function related to hugetlb to hugetlb.h (David).
- Introduce hugetlb_sysfs_initialized() and call it from hugetlb_sysfs_init() (David).
- Move hugetlb_register_all_nodes() into hugetlb_sysfs_init() (David).
- Fix implicit-function-declaration reported by LKP.
- Register per-node sysfs for online (N_ONLINE) nodes instead of N_MEMORY (Aneesh).
drivers/base/node.c | 8 ++++--
include/linux/hugetlb.h | 14 ++++++++++
mm/hugetlb.c | 70 ++++++++++++++++++++-----------------------------
3 files changed, 49 insertions(+), 43 deletions(-)
diff --git a/drivers/base/node.c b/drivers/base/node.c
index ed391cb09999..80b1e91b9608 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -20,6 +20,7 @@
#include <linux/pm_runtime.h>
#include <linux/swap.h>
#include <linux/slab.h>
+#include <linux/hugetlb.h>
static struct bus_type node_subsys = {
.name = "node",
@@ -608,10 +609,12 @@ static int register_node(struct node *node, int num)
node->dev.groups = node_dev_groups;
error = device_register(&node->dev);
- if (error)
+ if (error) {
put_device(&node->dev);
- else
+ } else {
+ hugetlb_register_node(node);
compaction_register_node(node);
+ }
return error;
}
@@ -625,6 +628,7 @@ static int register_node(struct node *node, int num)
*/
void unregister_node(struct node *node)
{
+ hugetlb_unregister_node(node);
compaction_unregister_node(node);
node_remove_accesses(node);
node_remove_caches(node);
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 890f7b6a2eff..a6fc49db0ce0 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -16,6 +16,7 @@
struct ctl_table;
struct user_struct;
struct mmu_gather;
+struct node;
#ifndef is_hugepd
typedef struct { unsigned long pd; } hugepd_t;
@@ -935,6 +936,11 @@ static inline void huge_ptep_modify_prot_commit(struct vm_area_struct *vma,
}
#endif
+#ifdef CONFIG_NUMA
+void hugetlb_register_node(struct node *node);
+void hugetlb_unregister_node(struct node *node);
+#endif
+
#else /* CONFIG_HUGETLB_PAGE */
struct hstate {};
@@ -1109,6 +1115,14 @@ static inline void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte)
{
}
+
+static inline void hugetlb_register_node(struct node *node)
+{
+}
+
+static inline void hugetlb_unregister_node(struct node *node)
+{
+}
#endif /* CONFIG_HUGETLB_PAGE */
static inline spinlock_t *huge_pte_lock(struct hstate *h,
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 0a37e80730b7..d776d55a97b2 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3869,24 +3869,8 @@ static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
return 0;
}
-static void __init hugetlb_sysfs_init(void)
-{
- struct hstate *h;
- int err;
-
- hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
- if (!hugepages_kobj)
- return;
-
- for_each_hstate(h) {
- err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
- hstate_kobjs, &hstate_attr_group);
- if (err)
- pr_err("HugeTLB: Unable to add hstate %s", h->name);
- }
-}
-
#ifdef CONFIG_NUMA
+static bool hugetlb_sysfs_initialized __ro_after_init;
/*
* node_hstate/s - associate per node hstate attributes, via their kobjects,
@@ -3942,7 +3926,7 @@ static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
* Unregister hstate attributes from a single node device.
* No-op if no hstate attributes attached.
*/
-static void hugetlb_unregister_node(struct node *node)
+void hugetlb_unregister_node(struct node *node)
{
struct hstate *h;
struct node_hstate *nhs = &node_hstates[node->dev.id];
@@ -3972,12 +3956,15 @@ static void hugetlb_unregister_node(struct node *node)
* Register hstate attributes for a single node device.
* No-op if attributes already registered.
*/
-static void hugetlb_register_node(struct node *node)
+void hugetlb_register_node(struct node *node)
{
struct hstate *h;
struct node_hstate *nhs = &node_hstates[node->dev.id];
int err;
+ if (!hugetlb_sysfs_initialized)
+ return;
+
if (nhs->hugepages_kobj)
return; /* already allocated */
@@ -3999,23 +3986,6 @@ static void hugetlb_register_node(struct node *node)
}
}
-static int __meminit hugetlb_memory_callback(struct notifier_block *self,
- unsigned long action, void *arg)
-{
- struct memory_notify *mnb = arg;
- int nid = mnb->status_change_nid;
-
- if (nid == NUMA_NO_NODE)
- return NOTIFY_DONE;
-
- if (action == MEM_GOING_ONLINE)
- hugetlb_register_node(node_devices[nid]);
- else if (action == MEM_CANCEL_ONLINE || action == MEM_OFFLINE)
- hugetlb_unregister_node(node_devices[nid]);
-
- return NOTIFY_OK;
-}
-
/*
* hugetlb init time: register hstate attributes for all registered node
* devices of nodes that have memory. All on-line nodes should have
@@ -4025,11 +3995,8 @@ static void __init hugetlb_register_all_nodes(void)
{
int nid;
- get_online_mems();
- hotplug_memory_notifier(hugetlb_memory_callback, 0);
- for_each_node_state(nid, N_MEMORY)
+ for_each_online_node(nid)
hugetlb_register_node(node_devices[nid]);
- put_online_mems();
}
#else /* !CONFIG_NUMA */
@@ -4053,6 +4020,28 @@ static inline __init void hugetlb_cma_check(void)
}
#endif
+static void __init hugetlb_sysfs_init(void)
+{
+ struct hstate *h;
+ int err;
+
+ hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
+ if (!hugepages_kobj)
+ return;
+
+ for_each_hstate(h) {
+ err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
+ hstate_kobjs, &hstate_attr_group);
+ if (err)
+ pr_err("HugeTLB: Unable to add hstate %s", h->name);
+ }
+
+#ifdef CONFIG_NUMA
+ hugetlb_sysfs_initialized = true;
+#endif
+ hugetlb_register_all_nodes();
+}
+
static int __init hugetlb_init(void)
{
int i;
@@ -4107,7 +4096,6 @@ static int __init hugetlb_init(void)
report_hugepages();
hugetlb_sysfs_init();
- hugetlb_register_all_nodes();
hugetlb_cgroup_file_init();
#ifdef CONFIG_SMP
--
2.11.0
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