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mm: vmalloc: remove global vmap_area_root rb-tree

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Store allocated objects in a separate nodes.  A va->va_start address is
converted into a correct node where it should be placed and resided.  An
addr_to_node() function is used to do a proper address conversion to
determine a node that contains a VA.

Such approach balances VAs across nodes as a result an access becomes
scalable.  Number of nodes in a system depends on number of CPUs.

Please note:

1. As of now allocated VAs are bound to a node-0. It means the
   patch does not give any difference comparing with a current
   behavior;

2. The global vmap_area_lock, vmap_area_root are removed as there
   is no need in it anymore. The vmap_area_list is still kept and
   is _empty_. It is exported for a kexec only;

3. The vmallocinfo and vread() have to be reworked to be able to
   handle multiple nodes.

[urezki@gmail.com: mark vmap_init_free_space() with __init tag]
  Link: https://lkml.kernel.org/r/20240111132628.299644-1-urezki@gmail.com
[urezki@gmail.com: fix a wrong value passed to __find_vmap_area()]
  Link: https://lkml.kernel.org/r/20240111121104.180993-1-urezki@gmail.com
Link: https://lkml.kernel.org/r/20240102184633.748113-5-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
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: 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>
This commit is contained in:
Uladzislau Rezki (Sony) 2024-01-02 19:46:26 +01:00 • committed by Andrew Morton
parent 7fa8cee003
commit d093602919
1 changed files with 175 additions and 69 deletions
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244
mm/vmalloc.c
View file

@ -728,11 +728,9 @@ EXPORT_SYMBOL(vmalloc_to_pfn);
#define DEBUG_AUGMENT_LOWEST_MATCH_CHECK 0
static DEFINE_SPINLOCK(vmap_area_lock);
static DEFINE_SPINLOCK(free_vmap_area_lock);
/* Export for kexec only */
LIST_HEAD(vmap_area_list);
static struct rb_root vmap_area_root = RB_ROOT;
static bool vmap_initialized __read_mostly;
static struct rb_root purge_vmap_area_root = RB_ROOT;
@ -772,6 +770,38 @@ static struct rb_root free_vmap_area_root = RB_ROOT;
*/
static DEFINE_PER_CPU(struct vmap_area *, ne_fit_preload_node);
/*
* An effective vmap-node logic. Users make use of nodes instead
* of a global heap. It allows to balance an access and mitigate
* contention.
*/
struct rb_list {
struct rb_root root;
struct list_head head;
spinlock_t lock;
};
static struct vmap_node {
/* Bookkeeping data of this node. */
struct rb_list busy;
} single;
static struct vmap_node *vmap_nodes = &single;
static __read_mostly unsigned int nr_vmap_nodes = 1;
static __read_mostly unsigned int vmap_zone_size = 1;
static inline unsigned int
addr_to_node_id(unsigned long addr)
{
return (addr / vmap_zone_size) % nr_vmap_nodes;
}
static inline struct vmap_node *
addr_to_node(unsigned long addr)
{
return &vmap_nodes[addr_to_node_id(addr)];
}
static __always_inline unsigned long
va_size(struct vmap_area *va)
{
@ -803,10 +833,11 @@ unsigned long vmalloc_nr_pages(void)
}
/* Look up the first VA which satisfies addr < va_end, NULL if none. */
static struct vmap_area *find_vmap_area_exceed_addr(unsigned long addr)
static struct vmap_area *
find_vmap_area_exceed_addr(unsigned long addr, struct rb_root *root)
{
struct vmap_area *va = NULL;
struct rb_node *n = vmap_area_root.rb_node;
struct rb_node *n = root->rb_node;
addr = (unsigned long)kasan_reset_tag((void *)addr);
@ -1552,12 +1583,14 @@ __alloc_vmap_area(struct rb_root *root, struct list_head *head,
*/
static void free_vmap_area(struct vmap_area *va)
{
struct vmap_node *vn = addr_to_node(va->va_start);
/*
* Remove from the busy tree/list.
*/
spin_lock(&vmap_area_lock);
unlink_va(va, &vmap_area_root);
spin_unlock(&vmap_area_lock);
spin_lock(&vn->busy.lock);
unlink_va(va, &vn->busy.root);
spin_unlock(&vn->busy.lock);
/*
* Insert/Merge it back to the free tree/list.
@ -1600,6 +1633,7 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
int node, gfp_t gfp_mask,
unsigned long va_flags)
{
struct vmap_node *vn;
struct vmap_area *va;
unsigned long freed;
unsigned long addr;
@ -1645,9 +1679,11 @@ retry:
va->vm = NULL;
va->flags = va_flags;
spin_lock(&vmap_area_lock);
insert_vmap_area(va, &vmap_area_root, &vmap_area_list);
spin_unlock(&vmap_area_lock);
vn = addr_to_node(va->va_start);
spin_lock(&vn->busy.lock);
insert_vmap_area(va, &vn->busy.root, &vn->busy.head);
spin_unlock(&vn->busy.lock);
BUG_ON(!IS_ALIGNED(va->va_start, align));
BUG_ON(va->va_start < vstart);
@ -1871,26 +1907,61 @@ static void free_unmap_vmap_area(struct vmap_area *va)
struct vmap_area *find_vmap_area(unsigned long addr)
{
struct vmap_node *vn;
struct vmap_area *va;
int i, j;
spin_lock(&vmap_area_lock);
va = __find_vmap_area(addr, &vmap_area_root);
spin_unlock(&vmap_area_lock);
/*
* An addr_to_node_id(addr) converts an address to a node index
* where a VA is located. If VA spans several zones and passed
* addr is not the same as va->va_start, what is not common, we
* may need to scan an extra nodes. See an example:
*
* <--va-->
* -|-----|-----|-----|-----|-
* 1 2 0 1
*
* VA resides in node 1 whereas it spans 1 and 2. If passed
* addr is within a second node we should do extra work. We
* should mention that it is rare and is a corner case from
* the other hand it has to be covered.
*/
i = j = addr_to_node_id(addr);
do {
vn = &vmap_nodes[i];
return va;
spin_lock(&vn->busy.lock);
va = __find_vmap_area(addr, &vn->busy.root);
spin_unlock(&vn->busy.lock);
if (va)
return va;
} while ((i = (i + 1) % nr_vmap_nodes) != j);
return NULL;
}
static struct vmap_area *find_unlink_vmap_area(unsigned long addr)
{
struct vmap_node *vn;
struct vmap_area *va;
int i, j;
spin_lock(&vmap_area_lock);
va = __find_vmap_area(addr, &vmap_area_root);
if (va)
unlink_va(va, &vmap_area_root);
spin_unlock(&vmap_area_lock);
i = j = addr_to_node_id(addr);
do {
vn = &vmap_nodes[i];
return va;
spin_lock(&vn->busy.lock);
va = __find_vmap_area(addr, &vn->busy.root);
if (va)
unlink_va(va, &vn->busy.root);
spin_unlock(&vn->busy.lock);
if (va)
return va;
} while ((i = (i + 1) % nr_vmap_nodes) != j);
return NULL;
}
/*** Per cpu kva allocator ***/
@ -2092,6 +2163,7 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
static void free_vmap_block(struct vmap_block *vb)
{
struct vmap_node *vn;
struct vmap_block *tmp;
struct xarray *xa;
@ -2099,9 +2171,10 @@ static void free_vmap_block(struct vmap_block *vb)
tmp = xa_erase(xa, addr_to_vb_idx(vb->va->va_start));
BUG_ON(tmp != vb);
spin_lock(&vmap_area_lock);
unlink_va(vb->va, &vmap_area_root);
spin_unlock(&vmap_area_lock);
vn = addr_to_node(vb->va->va_start);
spin_lock(&vn->busy.lock);
unlink_va(vb->va, &vn->busy.root);
spin_unlock(&vn->busy.lock);
free_vmap_area_noflush(vb->va);
kfree_rcu(vb, rcu_head);
@ -2525,9 +2598,11 @@ static inline void setup_vmalloc_vm_locked(struct vm_struct *vm,
static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
unsigned long flags, const void *caller)
{
spin_lock(&vmap_area_lock);
struct vmap_node *vn = addr_to_node(va->va_start);
spin_lock(&vn->busy.lock);
setup_vmalloc_vm_locked(vm, va, flags, caller);
spin_unlock(&vmap_area_lock);
spin_unlock(&vn->busy.lock);
}
static void clear_vm_uninitialized_flag(struct vm_struct *vm)
@ -3715,6 +3790,7 @@ finished:
*/
long vread_iter(struct iov_iter *iter, const char *addr, size_t count)
{
struct vmap_node *vn;
struct vmap_area *va;
struct vm_struct *vm;
char *vaddr;
@ -3728,8 +3804,11 @@ long vread_iter(struct iov_iter *iter, const char *addr, size_t count)
remains = count;
spin_lock(&vmap_area_lock);
va = find_vmap_area_exceed_addr((unsigned long)addr);
/* Hooked to node_0 so far. */
vn = addr_to_node(0);
spin_lock(&vn->busy.lock);
va = find_vmap_area_exceed_addr((unsigned long)addr, &vn->busy.root);
if (!va)
goto finished_zero;
@ -3737,7 +3816,7 @@ long vread_iter(struct iov_iter *iter, const char *addr, size_t count)
if ((unsigned long)addr + remains <= va->va_start)
goto finished_zero;
list_for_each_entry_from(va, &vmap_area_list, list) {
list_for_each_entry_from(va, &vn->busy.head, list) {
size_t copied;
if (remains == 0)
@ -3796,12 +3875,12 @@ long vread_iter(struct iov_iter *iter, const char *addr, size_t count)
}
finished_zero:
spin_unlock(&vmap_area_lock);
spin_unlock(&vn->busy.lock);
/* zero-fill memory holes */
return count - remains + zero_iter(iter, remains);
finished:
/* Nothing remains, or We couldn't copy/zero everything. */
spin_unlock(&vmap_area_lock);
spin_unlock(&vn->busy.lock);
return count - remains;
}
@ -4135,14 +4214,15 @@ retry:
}
/* insert all vm's */
spin_lock(&vmap_area_lock);
for (area = 0; area < nr_vms; area++) {
insert_vmap_area(vas[area], &vmap_area_root, &vmap_area_list);
struct vmap_node *vn = addr_to_node(vas[area]->va_start);
spin_lock(&vn->busy.lock);
insert_vmap_area(vas[area], &vn->busy.root, &vn->busy.head);
setup_vmalloc_vm_locked(vms[area], vas[area], VM_ALLOC,
pcpu_get_vm_areas);
spin_unlock(&vn->busy.lock);
}
spin_unlock(&vmap_area_lock);
/*
* Mark allocated areas as accessible. Do it now as a best-effort
@ -4253,55 +4333,57 @@ bool vmalloc_dump_obj(void *object)
{
void *objp = (void *)PAGE_ALIGN((unsigned long)object);
const void *caller;
struct vm_struct *vm;
struct vmap_area *va;
struct vmap_node *vn;
unsigned long addr;
unsigned int nr_pages;
bool success = false;
if (!spin_trylock(&vmap_area_lock))
return false;
va = __find_vmap_area((unsigned long)objp, &vmap_area_root);
if (!va) {
spin_unlock(&vmap_area_lock);
return false;
vn = addr_to_node((unsigned long)objp);
if (spin_trylock(&vn->busy.lock)) {
va = __find_vmap_area((unsigned long)objp, &vn->busy.root);
if (va && va->vm) {
addr = (unsigned long)va->vm->addr;
caller = va->vm->caller;
nr_pages = va->vm->nr_pages;
success = true;
}
spin_unlock(&vn->busy.lock);
}
vm = va->vm;
if (!vm) {
spin_unlock(&vmap_area_lock);
return false;
}
addr = (unsigned long)vm->addr;
caller = vm->caller;
nr_pages = vm->nr_pages;
spin_unlock(&vmap_area_lock);
pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n",
nr_pages, addr, caller);
return true;
if (success)
pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n",
nr_pages, addr, caller);
return success;
}
#endif
#ifdef CONFIG_PROC_FS
static void *s_start(struct seq_file *m, loff_t *pos)
__acquires(&vmap_purge_lock)
__acquires(&vmap_area_lock)
{
mutex_lock(&vmap_purge_lock);
spin_lock(&vmap_area_lock);
struct vmap_node *vn = addr_to_node(0);
return seq_list_start(&vmap_area_list, *pos);
mutex_lock(&vmap_purge_lock);
spin_lock(&vn->busy.lock);
return seq_list_start(&vn->busy.head, *pos);
}
static void *s_next(struct seq_file *m, void *p, loff_t *pos)
{
return seq_list_next(p, &vmap_area_list, pos);
struct vmap_node *vn = addr_to_node(0);
return seq_list_next(p, &vn->busy.head, pos);
}
static void s_stop(struct seq_file *m, void *p)
__releases(&vmap_area_lock)
__releases(&vmap_purge_lock)
{
spin_unlock(&vmap_area_lock);
struct vmap_node *vn = addr_to_node(0);
spin_unlock(&vn->busy.lock);
mutex_unlock(&vmap_purge_lock);
}
@ -4344,9 +4426,11 @@ static void show_purge_info(struct seq_file *m)
static int s_show(struct seq_file *m, void *p)
{
struct vmap_node *vn;
struct vmap_area *va;
struct vm_struct *v;
vn = addr_to_node(0);
va = list_entry(p, struct vmap_area, list);
if (!va->vm) {
@ -4397,7 +4481,7 @@ static int s_show(struct seq_file *m, void *p)
* As a final step, dump "unpurged" areas.
*/
final:
if (list_is_last(&va->list, &vmap_area_list))
if (list_is_last(&va->list, &vn->busy.head))
show_purge_info(m);
return 0;
@ -4424,11 +4508,12 @@ module_init(proc_vmalloc_init);
#endif
static void vmap_init_free_space(void)
static void __init vmap_init_free_space(void)
{
unsigned long vmap_start = 1;
const unsigned long vmap_end = ULONG_MAX;
struct vmap_area *busy, *free;
struct vmap_area *free;
struct vm_struct *busy;
/*
* B F B B B F
@ -4436,12 +4521,12 @@ static void vmap_init_free_space(void)
* | The KVA space |
* |<--------------------------------->|
*/
list_for_each_entry(busy, &vmap_area_list, list) {
if (busy->va_start - vmap_start > 0) {
for (busy = vmlist; busy; busy = busy->next) {
if ((unsigned long) busy->addr - vmap_start > 0) {
free = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT);
if (!WARN_ON_ONCE(!free)) {
free->va_start = vmap_start;
free->va_end = busy->va_start;
free->va_end = (unsigned long) busy->addr;
insert_vmap_area_augment(free, NULL,
&free_vmap_area_root,
@ -4449,7 +4534,7 @@ static void vmap_init_free_space(void)
}
}
vmap_start = busy->va_end;
vmap_start = (unsigned long) busy->addr + busy->size;
}
if (vmap_end - vmap_start > 0) {
@ -4465,9 +4550,23 @@ static void vmap_init_free_space(void)
}
}
static void vmap_init_nodes(void)
{
struct vmap_node *vn;
int i;
for (i = 0; i < nr_vmap_nodes; i++) {
vn = &vmap_nodes[i];
vn->busy.root = RB_ROOT;
INIT_LIST_HEAD(&vn->busy.head);
spin_lock_init(&vn->busy.lock);
}
}
void __init vmalloc_init(void)
{
struct vmap_area *va;
struct vmap_node *vn;
struct vm_struct *tmp;
int i;
@ -4489,6 +4588,11 @@ void __init vmalloc_init(void)
xa_init(&vbq->vmap_blocks);
}
/*
* Setup nodes before importing vmlist.
*/
vmap_init_nodes();
/* Import existing vmlist entries. */
for (tmp = vmlist; tmp; tmp = tmp->next) {
va = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT);
@ -4498,7 +4602,9 @@ void __init vmalloc_init(void)
va->va_start = (unsigned long)tmp->addr;
va->va_end = va->va_start + tmp->size;
va->vm = tmp;
insert_vmap_area(va, &vmap_area_root, &vmap_area_list);
vn = addr_to_node(va->va_start);
insert_vmap_area(va, &vn->busy.root, &vn->busy.head);
}
/*