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mm: hugetlb: eliminate memory-less nodes handling

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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 4faf8d950e
("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 9b5e5d0fdc,
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]
Link: https://lkml.kernel.org/r/20220914072603.60293-3-songmuchun@bytedance.com
Suggested-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Muchun Song 2022-09-14 15:26:03 +08:00 committed by Andrew Morton
parent b958d4d08f
commit a4a00b451e
3 changed files with 49 additions and 43 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/base/node.c
View File

@ -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);

14
include/linux/hugetlb.h
View File

@ -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,

70
mm/hugetlb.c
View File

@ -3871,24 +3871,8 @@ 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,
@ -3944,7 +3928,7 @@ 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];
@ -3974,12 +3958,15 @@ 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 */
@ -4001,23 +3988,6 @@ 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
@ -4027,11 +3997,8 @@ 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 */
@ -4055,6 +4022,28 @@ 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;
@ -4109,7 +4098,6 @@ static int __init hugetlb_init(void)
report_hugepages();
hugetlb_sysfs_init();
hugetlb_register_all_nodes();
hugetlb_cgroup_file_init();
#ifdef CONFIG_SMP