The patch titled
Subject: mm: hugetlb: eliminate memoryless nodes handling
has been added to the -mm mm-unstable branch. Its filename is
mm-hugetlb-eliminate-memory-less-nodes-handling.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hugetlb-eliminate-memory-less-nodes-handling.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: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Subject: mm: hugetlb: eliminate memoryless nodes handling
Date: Thu, 8 Sep 2022 15:58:26 +0800
The memory-notify-based approach aims to handle meoryless nodes, however
it just adds complexity to the code as pointed out by David in [1].
The handling of memoryless nodes is introduced by commit 4faf8d950ec4
("hugetlb: handle memory hot-plug events"). In 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, the hotplug callback was added because in
hugetlb_register_all_nodes() we register sysfs nodes only for N_MEMORY
nodes - see commit 9b5e5d0fdc91, which said it was a preparation for
handling memoryless nodes via memory hotplug. Since we want to remove
memory hotplug, 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@xxxxxxxxxx/ [1]
Link: https://lkml.kernel.org/r/20220908075826.37094-1-songmuchun@xxxxxxxxxxxxx
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Rafael J. Wysocki <rafael@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/base/node.c | 8 ++-
include/linux/hugetlb.h | 14 ++++++
mm/hugetlb.c | 82 +++++++++++++++++---------------------
3 files changed, 58 insertions(+), 46 deletions(-)
--- a/drivers/base/node.c~mm-hugetlb-eliminate-memory-less-nodes-handling
+++ a/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 *no
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 *no
*/
void unregister_node(struct node *node)
{
+ hugetlb_unregister_node(node);
compaction_unregister_node(node);
node_remove_accesses(node);
node_remove_caches(node);
--- a/include/linux/hugetlb.h~mm-hugetlb-eliminate-memory-less-nodes-handling
+++ a/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
}
#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(struc
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,
--- a/mm/hugetlb.c~mm-hugetlb-eliminate-memory-less-nodes-handling
+++ a/mm/hugetlb.c
@@ -3864,24 +3864,14 @@ static int hugetlb_sysfs_add_hstate(stru
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;
+#ifdef CONFIG_NUMA
+static bool hugetlb_sysfs_initialized __ro_after_init;
- 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);
- }
+static inline void hugetlb_mark_sysfs_initialized(void)
+{
+ hugetlb_sysfs_initialized = true;
}
-#ifdef CONFIG_NUMA
/*
* node_hstate/s - associate per node hstate attributes, via their kobjects,
@@ -3937,7 +3927,7 @@ static struct hstate *kobj_to_node_hstat
* 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];
@@ -3967,19 +3957,22 @@ static void hugetlb_unregister_node(stru
* Register hstate attributes for a single node device.
* No-op if attributes already registered.
*/
-static int 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 0; /* already allocated */
+ return; /* already allocated */
nhs->hugepages_kobj = kobject_create_and_add("hugepages",
&node->dev.kobj);
if (!nhs->hugepages_kobj)
- return -ENOMEM;
+ return;
for_each_hstate(h) {
err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
@@ -3989,28 +3982,9 @@ static int hugetlb_register_node(struct
pr_err("HugeTLB: Unable to add hstate %s for node %d\n",
h->name, node->dev.id);
hugetlb_unregister_node(node);
- return -ENOMEM;
+ break;
}
}
- return 0;
-}
-
-static int __meminit hugetlb_memory_callback(struct notifier_block *self,
- unsigned long action, void *arg)
-{
- int ret = 0;
- struct memory_notify *mnb = arg;
- int nid = mnb->status_change_nid;
-
- if (nid == NUMA_NO_NODE)
- return NOTIFY_DONE;
-
- if (action == MEM_GOING_ONLINE)
- ret = hugetlb_register_node(node_devices[nid]);
- else if (action == MEM_CANCEL_ONLINE || action == MEM_OFFLINE)
- hugetlb_unregister_node(node_devices[nid]);
-
- return notifier_from_errno(ret);
}
/*
@@ -4022,11 +3996,8 @@ static void __init hugetlb_register_all_
{
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 */
@@ -4040,8 +4011,32 @@ static struct hstate *kobj_to_node_hstat
static void hugetlb_register_all_nodes(void) { }
+static inline void hugetlb_mark_sysfs_initialized(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);
+ }
+
+ hugetlb_mark_sysfs_initialized();
+ hugetlb_register_all_nodes();
+}
+
#ifdef CONFIG_CMA
static void __init hugetlb_cma_check(void);
#else
@@ -4104,7 +4099,6 @@ static int __init hugetlb_init(void)
report_hugepages();
hugetlb_sysfs_init();
- hugetlb_register_all_nodes();
hugetlb_cgroup_file_init();
#ifdef CONFIG_SMP
_
Patches currently in -mm which might be from songmuchun@xxxxxxxxxxxxx are
mm-hugetlb_vmemmap-simplify-reset_struct_pages.patch
mm-hugetlb-simplify-per-node-sysfs-creation-and-removal.patch
mm-hugetlb-eliminate-memory-less-nodes-handling.patch
