From 8ecb1a59d6c6674bc98e4eee0c2482490748e21a Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Tue, 8 Mar 2016 11:54:14 +0100 Subject: [PATCH] s390/mm: use RCU for gmap notifier list and the per-mm gmap list The gmap notifier list and the gmap list in the mm_struct change rarely. Use RCU to optimize the reader of these lists. Reviewed-by: David Hildenbrand Signed-off-by: Martin Schwidefsky Signed-off-by: Christian Borntraeger --- arch/s390/include/asm/gmap.h | 1 + arch/s390/include/asm/mmu.h | 11 +++++--- arch/s390/include/asm/mmu_context.h | 3 ++- arch/s390/mm/gmap.c | 39 +++++++++++++++++------------ arch/s390/mm/pgalloc.c | 16 ++++++------ 5 files changed, 41 insertions(+), 29 deletions(-) diff --git a/arch/s390/include/asm/gmap.h b/arch/s390/include/asm/gmap.h index bc0eadf9ed8e..2cf49624af99 100644 --- a/arch/s390/include/asm/gmap.h +++ b/arch/s390/include/asm/gmap.h @@ -39,6 +39,7 @@ struct gmap { */ struct gmap_notifier { struct list_head list; + struct rcu_head rcu; void (*notifier_call)(struct gmap *gmap, unsigned long start, unsigned long end); }; diff --git a/arch/s390/include/asm/mmu.h b/arch/s390/include/asm/mmu.h index 081b2ad99d73..b941528cc49e 100644 --- a/arch/s390/include/asm/mmu.h +++ b/arch/s390/include/asm/mmu.h @@ -8,8 +8,9 @@ typedef struct { cpumask_t cpu_attach_mask; atomic_t attach_count; unsigned int flush_mm; - spinlock_t list_lock; + spinlock_t pgtable_lock; struct list_head pgtable_list; + spinlock_t gmap_lock; struct list_head gmap_list; unsigned long asce; unsigned long asce_limit; @@ -22,9 +23,11 @@ typedef struct { unsigned int use_skey:1; } mm_context_t; -#define INIT_MM_CONTEXT(name) \ - .context.list_lock = __SPIN_LOCK_UNLOCKED(name.context.list_lock), \ - .context.pgtable_list = LIST_HEAD_INIT(name.context.pgtable_list), \ +#define INIT_MM_CONTEXT(name) \ + .context.pgtable_lock = \ + __SPIN_LOCK_UNLOCKED(name.context.pgtable_lock), \ + .context.pgtable_list = LIST_HEAD_INIT(name.context.pgtable_list), \ + .context.gmap_lock = __SPIN_LOCK_UNLOCKED(name.context.gmap_lock), \ .context.gmap_list = LIST_HEAD_INIT(name.context.gmap_list), static inline int tprot(unsigned long addr) diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h index c837b79b455d..3ce3854b7a41 100644 --- a/arch/s390/include/asm/mmu_context.h +++ b/arch/s390/include/asm/mmu_context.h @@ -15,8 +15,9 @@ static inline int init_new_context(struct task_struct *tsk, struct mm_struct *mm) { - spin_lock_init(&mm->context.list_lock); + spin_lock_init(&mm->context.pgtable_lock); INIT_LIST_HEAD(&mm->context.pgtable_list); + spin_lock_init(&mm->context.gmap_lock); INIT_LIST_HEAD(&mm->context.gmap_list); cpumask_clear(&mm->context.cpu_attach_mask); atomic_set(&mm->context.attach_count, 0); diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c index b5820bf47ec6..8b56423a8297 100644 --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -70,9 +70,9 @@ struct gmap *gmap_alloc(struct mm_struct *mm, unsigned long limit) gmap->asce = atype | _ASCE_TABLE_LENGTH | _ASCE_USER_BITS | __pa(table); gmap->asce_end = limit; - down_write(&mm->mmap_sem); - list_add(&gmap->list, &mm->context.gmap_list); - up_write(&mm->mmap_sem); + spin_lock(&mm->context.gmap_lock); + list_add_rcu(&gmap->list, &mm->context.gmap_list); + spin_unlock(&mm->context.gmap_lock); return gmap; out_free: @@ -128,14 +128,16 @@ void gmap_free(struct gmap *gmap) else __tlb_flush_global(); + spin_lock(&gmap->mm->context.gmap_lock); + list_del_rcu(&gmap->list); + spin_unlock(&gmap->mm->context.gmap_lock); + synchronize_rcu(); + /* Free all segment & region tables. */ list_for_each_entry_safe(page, next, &gmap->crst_list, lru) __free_pages(page, 2); gmap_radix_tree_free(&gmap->guest_to_host); gmap_radix_tree_free(&gmap->host_to_guest); - down_write(&gmap->mm->mmap_sem); - list_del(&gmap->list); - up_write(&gmap->mm->mmap_sem); kfree(gmap); } EXPORT_SYMBOL_GPL(gmap_free); @@ -369,11 +371,13 @@ void gmap_unlink(struct mm_struct *mm, unsigned long *table, struct gmap *gmap; int flush; - list_for_each_entry(gmap, &mm->context.gmap_list, list) { + rcu_read_lock(); + list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) { flush = __gmap_unlink_by_vmaddr(gmap, vmaddr); if (flush) gmap_flush_tlb(gmap); } + rcu_read_unlock(); } /** @@ -555,7 +559,7 @@ static DEFINE_SPINLOCK(gmap_notifier_lock); void gmap_register_ipte_notifier(struct gmap_notifier *nb) { spin_lock(&gmap_notifier_lock); - list_add(&nb->list, &gmap_notifier_list); + list_add_rcu(&nb->list, &gmap_notifier_list); spin_unlock(&gmap_notifier_lock); } EXPORT_SYMBOL_GPL(gmap_register_ipte_notifier); @@ -567,8 +571,9 @@ EXPORT_SYMBOL_GPL(gmap_register_ipte_notifier); void gmap_unregister_ipte_notifier(struct gmap_notifier *nb) { spin_lock(&gmap_notifier_lock); - list_del_init(&nb->list); + list_del_rcu(&nb->list); spin_unlock(&gmap_notifier_lock); + synchronize_rcu(); } EXPORT_SYMBOL_GPL(gmap_unregister_ipte_notifier); @@ -662,16 +667,18 @@ void ptep_notify(struct mm_struct *mm, unsigned long vmaddr, pte_t *pte) offset = ((unsigned long) pte) & (255 * sizeof(pte_t)); offset = offset * (4096 / sizeof(pte_t)); - spin_lock(&gmap_notifier_lock); - list_for_each_entry(gmap, &mm->context.gmap_list, list) { + rcu_read_lock(); + list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) { + spin_lock(&gmap->guest_table_lock); table = radix_tree_lookup(&gmap->host_to_guest, vmaddr >> PMD_SHIFT); - if (!table) - continue; - gaddr = __gmap_segment_gaddr(table) + offset; - gmap_call_notifier(gmap, gaddr, gaddr + PAGE_SIZE - 1); + if (table) + gaddr = __gmap_segment_gaddr(table) + offset; + spin_unlock(&gmap->guest_table_lock); + if (table) + gmap_call_notifier(gmap, gaddr, gaddr + PAGE_SIZE - 1); } - spin_unlock(&gmap_notifier_lock); + rcu_read_unlock(); } EXPORT_SYMBOL_GPL(ptep_notify); diff --git a/arch/s390/mm/pgalloc.c b/arch/s390/mm/pgalloc.c index e8b5962ac12a..7be1f94f70a8 100644 --- a/arch/s390/mm/pgalloc.c +++ b/arch/s390/mm/pgalloc.c @@ -149,7 +149,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm) /* Try to get a fragment of a 4K page as a 2K page table */ if (!mm_alloc_pgste(mm)) { table = NULL; - spin_lock_bh(&mm->context.list_lock); + spin_lock_bh(&mm->context.pgtable_lock); if (!list_empty(&mm->context.pgtable_list)) { page = list_first_entry(&mm->context.pgtable_list, struct page, lru); @@ -164,7 +164,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm) list_del(&page->lru); } } - spin_unlock_bh(&mm->context.list_lock); + spin_unlock_bh(&mm->context.pgtable_lock); if (table) return table; } @@ -187,9 +187,9 @@ unsigned long *page_table_alloc(struct mm_struct *mm) /* Return the first 2K fragment of the page */ atomic_set(&page->_mapcount, 1); clear_table(table, _PAGE_INVALID, PAGE_SIZE); - spin_lock_bh(&mm->context.list_lock); + spin_lock_bh(&mm->context.pgtable_lock); list_add(&page->lru, &mm->context.pgtable_list); - spin_unlock_bh(&mm->context.list_lock); + spin_unlock_bh(&mm->context.pgtable_lock); } return table; } @@ -203,13 +203,13 @@ void page_table_free(struct mm_struct *mm, unsigned long *table) if (!mm_alloc_pgste(mm)) { /* Free 2K page table fragment of a 4K page */ bit = (__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t)); - spin_lock_bh(&mm->context.list_lock); + spin_lock_bh(&mm->context.pgtable_lock); mask = atomic_xor_bits(&page->_mapcount, 1U << bit); if (mask & 3) list_add(&page->lru, &mm->context.pgtable_list); else list_del(&page->lru); - spin_unlock_bh(&mm->context.list_lock); + spin_unlock_bh(&mm->context.pgtable_lock); if (mask != 0) return; } @@ -235,13 +235,13 @@ void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table, return; } bit = (__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t)); - spin_lock_bh(&mm->context.list_lock); + spin_lock_bh(&mm->context.pgtable_lock); mask = atomic_xor_bits(&page->_mapcount, 0x11U << bit); if (mask & 3) list_add_tail(&page->lru, &mm->context.pgtable_list); else list_del(&page->lru); - spin_unlock_bh(&mm->context.list_lock); + spin_unlock_bh(&mm->context.pgtable_lock); table = (unsigned long *) (__pa(table) | (1U << bit)); tlb_remove_table(tlb, table); } -- 2.45.2