From a4a00b451ef5e1deb959088e25e248f4ee399792 Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Wed, 14 Sep 2022 15:26:03 +0800 Subject: [PATCH] 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] Link: https://lkml.kernel.org/r/20220914072603.60293-3-songmuchun@bytedance.com Suggested-by: David Hildenbrand Signed-off-by: Muchun Song Acked-by: David Hildenbrand Cc: Andi Kleen Cc: Greg Kroah-Hartman Cc: Mike Kravetz Cc: Oscar Salvador Cc: Rafael J. Wysocki Signed-off-by: Andrew Morton --- 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 ed391cb..80b1e91 100644 --- a/drivers/base/node.c +++ b/drivers/base/node.c @@ -20,6 +20,7 @@ #include #include #include +#include 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 57e7295..6d7f397 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 397f298..0b1ab5a 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -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 -- 2.7.4