From: "Uladzislau Rezki (Sony)" urezki@gmail.com
mainline inclusion from mainline-v6.9-rc1 commit 282631cb2447318e2a55b41a665dbe8571c46d70 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9CHG1 CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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Similar to busy VA, lazily-freed area is stored to a node it belongs to. Such approach does not require any global locking primitive, instead an access becomes scalable what mitigates a contention.
This patch removes a global purge-lock, global purge-tree and global purge list.
Link: https://lkml.kernel.org/r/20240102184633.748113-7-urezki@gmail.com Signed-off-by: Uladzislau Rezki (Sony) urezki@gmail.com Reviewed-by: Baoquan He bhe@redhat.com Cc: Christoph Hellwig hch@lst.de Cc: Dave Chinner david@fromorbit.com Cc: Joel Fernandes (Google) joel@joelfernandes.org Cc: Kazuhito Hagio k-hagio-ab@nec.com Cc: Liam R. Howlett Liam.Howlett@oracle.com Cc: Lorenzo Stoakes lstoakes@gmail.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Oleksiy Avramchenko oleksiy.avramchenko@sony.com Cc: Paul E. McKenney paulmck@kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org (cherry picked from commit 282631cb2447318e2a55b41a665dbe8571c46d70) Signed-off-by: Kefeng Wang wangkefeng.wang@huawei.com Signed-off-by: ZhangPeng zhangpeng362@huawei.com --- mm/vmalloc.c | 135 +++++++++++++++++++++++++++++++-------------------- 1 file changed, 82 insertions(+), 53 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c index beb5a6e6ebde..adf239513496 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -803,10 +803,6 @@ EXPORT_SYMBOL(vmalloc_to_pfn); static DEFINE_SPINLOCK(free_vmap_area_lock); static bool vmap_initialized __read_mostly;
-static struct rb_root purge_vmap_area_root = RB_ROOT; -static LIST_HEAD(purge_vmap_area_list); -static DEFINE_SPINLOCK(purge_vmap_area_lock); - /* * This kmem_cache is used for vmap_area objects. Instead of * allocating from slab we reuse an object from this cache to @@ -854,6 +850,12 @@ struct rb_list { static struct vmap_node { /* Bookkeeping data of this node. */ struct rb_list busy; + struct rb_list lazy; + + /* + * Ready-to-free areas. + */ + struct list_head purge_list; } single;
static struct vmap_node *vmap_nodes = &single; @@ -1838,40 +1840,22 @@ static DEFINE_MUTEX(vmap_purge_lock);
/* for per-CPU blocks */ static void purge_fragmented_blocks_allcpus(void); +static cpumask_t purge_nodes;
/* * Purges all lazily-freed vmap areas. */ -static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end) +static unsigned long +purge_vmap_node(struct vmap_node *vn) { - unsigned long resched_threshold; - unsigned int num_purged_areas = 0; - struct list_head local_purge_list; + unsigned long num_purged_areas = 0; struct vmap_area *va, *n_va;
- lockdep_assert_held(&vmap_purge_lock); - - spin_lock(&purge_vmap_area_lock); - purge_vmap_area_root = RB_ROOT; - list_replace_init(&purge_vmap_area_list, &local_purge_list); - spin_unlock(&purge_vmap_area_lock); - - if (unlikely(list_empty(&local_purge_list))) - goto out; - - start = min(start, - list_first_entry(&local_purge_list, - struct vmap_area, list)->va_start); - - end = max(end, - list_last_entry(&local_purge_list, - struct vmap_area, list)->va_end); - - flush_tlb_kernel_range(start, end); - resched_threshold = lazy_max_pages() << 1; + if (list_empty(&vn->purge_list)) + return 0;
spin_lock(&free_vmap_area_lock); - list_for_each_entry_safe(va, n_va, &local_purge_list, list) { + list_for_each_entry_safe(va, n_va, &vn->purge_list, list) { unsigned long nr = (va->va_end - va->va_start) >> PAGE_SHIFT; unsigned long orig_start = va->va_start; unsigned long orig_end = va->va_end; @@ -1893,13 +1877,55 @@ static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end)
atomic_long_sub(nr, &vmap_lazy_nr); num_purged_areas++; - - if (atomic_long_read(&vmap_lazy_nr) < resched_threshold) - cond_resched_lock(&free_vmap_area_lock); } spin_unlock(&free_vmap_area_lock);
-out: + return num_purged_areas; +} + +/* + * Purges all lazily-freed vmap areas. + */ +static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end) +{ + unsigned long num_purged_areas = 0; + struct vmap_node *vn; + int i; + + lockdep_assert_held(&vmap_purge_lock); + purge_nodes = CPU_MASK_NONE; + + for (i = 0; i < nr_vmap_nodes; i++) { + vn = &vmap_nodes[i]; + + INIT_LIST_HEAD(&vn->purge_list); + + if (RB_EMPTY_ROOT(&vn->lazy.root)) + continue; + + spin_lock(&vn->lazy.lock); + WRITE_ONCE(vn->lazy.root.rb_node, NULL); + list_replace_init(&vn->lazy.head, &vn->purge_list); + spin_unlock(&vn->lazy.lock); + + start = min(start, list_first_entry(&vn->purge_list, + struct vmap_area, list)->va_start); + + end = max(end, list_last_entry(&vn->purge_list, + struct vmap_area, list)->va_end); + + cpumask_set_cpu(i, &purge_nodes); + } + + if (cpumask_weight(&purge_nodes) > 0) { + flush_tlb_kernel_range(start, end); + + for_each_cpu(i, &purge_nodes) { + vn = &nodes[i]; + num_purged_areas += purge_vmap_node(vn); + } + } + trace_purge_vmap_area_lazy(start, end, num_purged_areas); return num_purged_areas > 0; } @@ -1918,16 +1944,9 @@ static void reclaim_and_purge_vmap_areas(void)
static void drain_vmap_area_work(struct work_struct *work) { - unsigned long nr_lazy; - - do { - mutex_lock(&vmap_purge_lock); - __purge_vmap_area_lazy(ULONG_MAX, 0); - mutex_unlock(&vmap_purge_lock); - - /* Recheck if further work is required. */ - nr_lazy = atomic_long_read(&vmap_lazy_nr); - } while (nr_lazy > lazy_max_pages()); + mutex_lock(&vmap_purge_lock); + __purge_vmap_area_lazy(ULONG_MAX, 0); + mutex_unlock(&vmap_purge_lock); }
/* @@ -1937,6 +1956,7 @@ static void drain_vmap_area_work(struct work_struct *work) */ static void free_vmap_area_noflush(struct vmap_area *va) { + struct vmap_node *vn = addr_to_node(va->va_start); unsigned long nr_lazy_max = lazy_max_pages(); unsigned long va_start = va->va_start; unsigned long nr_lazy; @@ -1950,10 +1970,9 @@ static void free_vmap_area_noflush(struct vmap_area *va) /* * Merge or place it to the purge tree/list. */ - spin_lock(&purge_vmap_area_lock); - merge_or_add_vmap_area(va, - &purge_vmap_area_root, &purge_vmap_area_list); - spin_unlock(&purge_vmap_area_lock); + spin_lock(&vn->lazy.lock); + merge_or_add_vmap_area(va, &vn->lazy.root, &vn->lazy.head); + spin_unlock(&vn->lazy.lock);
trace_free_vmap_area_noflush(va_start, nr_lazy, nr_lazy_max);
@@ -4686,15 +4705,21 @@ static void show_numa_info(struct seq_file *m, struct vm_struct *v)
static void show_purge_info(struct seq_file *m) { + struct vmap_node *vn; struct vmap_area *va; + int i;
- spin_lock(&purge_vmap_area_lock); - list_for_each_entry(va, &purge_vmap_area_list, list) { - seq_printf(m, "0x%pK-0x%pK %7ld unpurged vm_area\n", - (void *)va->va_start, (void *)va->va_end, - va->va_end - va->va_start); + for (i = 0; i < nr_vmap_nodes; i++) { + vn = &vmap_nodes[i]; + + spin_lock(&vn->lazy.lock); + list_for_each_entry(va, &vn->lazy.head, list) { + seq_printf(m, "0x%pK-0x%pK %7ld unpurged vm_area\n", + (void *)va->va_start, (void *)va->va_end, + va->va_end - va->va_start); + } + spin_unlock(&vn->lazy.lock); } - spin_unlock(&purge_vmap_area_lock); }
static int s_show(struct seq_file *m, void *p) @@ -4836,6 +4861,10 @@ static void vmap_init_nodes(void) vn->busy.root = RB_ROOT; INIT_LIST_HEAD(&vn->busy.head); spin_lock_init(&vn->busy.lock); + + vn->lazy.root = RB_ROOT; + INIT_LIST_HEAD(&vn->lazy.head); + spin_lock_init(&vn->lazy.lock); } }