mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity

mm/slub.c: avoid slub allocation while holding list_lock 

If we are already under list_lock, don't call kmalloc().  Otherwise we
will run into a deadlock because kmalloc() also tries to grab the same
lock.

Fix the problem by using a static bitmap instead.

  WARNING: possible recursive locking detected
  --------------------------------------------
  mount-encrypted/4921 is trying to acquire lock:
  (&(&n->list_lock)->rlock){-.-.}, at: ___slab_alloc+0x104/0x437

  but task is already holding lock:
  (&(&n->list_lock)->rlock){-.-.}, at: __kmem_cache_shutdown+0x81/0x3cb

  other info that might help us debug this:
   Possible unsafe locking scenario:

         CPU0
         ----
    lock(&(&n->list_lock)->rlock);
    lock(&(&n->list_lock)->rlock);

   *** DEADLOCK ***

Link: http://lkml.kernel.org/r/20191108193958.205102-2-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Yu Zhao 2020-01-30 22:11:57 -08:00 committed by Linus Torvalds
parent 25b69918d9
commit 90e9f6a66c
1 changed files with 47 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

88
mm/slub.c
View File

@ -439,19 +439,38 @@ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
}
#ifdef CONFIG_SLUB_DEBUG
static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)];
static DEFINE_SPINLOCK(object_map_lock);
/*
* Determine a map of object in use on a page.
*
* Node listlock must be held to guarantee that the page does
* not vanish from under us.
*/
static void get_map(struct kmem_cache *s, struct page *page, unsigned long *map)
static unsigned long *get_map(struct kmem_cache *s, struct page *page)
{
void *p;
void *addr = page_address(page);
VM_BUG_ON(!irqs_disabled());
spin_lock(&object_map_lock);
bitmap_zero(object_map, page->objects);
for (p = page->freelist; p; p = get_freepointer(s, p))
set_bit(slab_index(p, s, addr), map);
set_bit(slab_index(p, s, addr), object_map);
return object_map;
}
static void put_map(unsigned long *map)
{
VM_BUG_ON(map != object_map);
lockdep_assert_held(&object_map_lock);
spin_unlock(&object_map_lock);
}
static inline unsigned int size_from_object(struct kmem_cache *s)
@ -3675,13 +3694,12 @@ static void list_slab_objects(struct kmem_cache *s, struct page *page,
#ifdef CONFIG_SLUB_DEBUG
void *addr = page_address(page);
void *p;
unsigned long *map = bitmap_zalloc(page->objects, GFP_ATOMIC);
if (!map)
return;
unsigned long *map;
slab_err(s, page, text, s->name);
slab_lock(page);
get_map(s, page, map);
map = get_map(s, page);
for_each_object(p, s, addr, page->objects) {
if (!test_bit(slab_index(p, s, addr), map)) {
@ -3689,8 +3707,9 @@ static void list_slab_objects(struct kmem_cache *s, struct page *page,
print_tracking(s, p);
}
}
put_map(map);
slab_unlock(page);
bitmap_free(map);
#endif
}
@ -4384,19 +4403,19 @@ static int count_total(struct page *page)
#endif
#ifdef CONFIG_SLUB_DEBUG
static void validate_slab(struct kmem_cache *s, struct page *page,
unsigned long *map)
static void validate_slab(struct kmem_cache *s, struct page *page)
{
void *p;
void *addr = page_address(page);
unsigned long *map;
slab_lock(page);
if (!check_slab(s, page) || !on_freelist(s, page, NULL))
return;
goto unlock;
/* Now we know that a valid freelist exists */
bitmap_zero(map, page->objects);
get_map(s, page, map);
map = get_map(s, page);
for_each_object(p, s, addr, page->objects) {
u8 val = test_bit(slab_index(p, s, addr), map) ?
SLUB_RED_INACTIVE : SLUB_RED_ACTIVE;
@ -4404,18 +4423,13 @@ static void validate_slab(struct kmem_cache *s, struct page *page,
if (!check_object(s, page, p, val))
break;
}
}
static void validate_slab_slab(struct kmem_cache *s, struct page *page,
unsigned long *map)
{
slab_lock(page);
validate_slab(s, page, map);
put_map(map);
unlock:
slab_unlock(page);
}
static int validate_slab_node(struct kmem_cache *s,
struct kmem_cache_node *n, unsigned long *map)
struct kmem_cache_node *n)
{
unsigned long count = 0;
struct page *page;
@ -4424,7 +4438,7 @@ static int validate_slab_node(struct kmem_cache *s,
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry(page, &n->partial, slab_list) {
validate_slab_slab(s, page, map);
validate_slab(s, page);
count++;
}
if (count != n->nr_partial)
@ -4435,7 +4449,7 @@ static int validate_slab_node(struct kmem_cache *s,
goto out;
list_for_each_entry(page, &n->full, slab_list) {
validate_slab_slab(s, page, map);
validate_slab(s, page);
count++;
}
if (count != atomic_long_read(&n->nr_slabs))
@ -4452,15 +4466,11 @@ static long validate_slab_cache(struct kmem_cache *s)
int node;
unsigned long count = 0;
struct kmem_cache_node *n;
unsigned long *map = bitmap_alloc(oo_objects(s->max), GFP_KERNEL);
if (!map)
return -ENOMEM;
flush_all(s);
for_each_kmem_cache_node(s, node, n)
count += validate_slab_node(s, n, map);
bitmap_free(map);
count += validate_slab_node(s, n);
return count;
}
/*
@ -4590,18 +4600,17 @@ static int add_location(struct loc_track *t, struct kmem_cache *s,
}
static void process_slab(struct loc_track *t, struct kmem_cache *s,
struct page *page, enum track_item alloc,
unsigned long *map)
struct page *page, enum track_item alloc)
{
void *addr = page_address(page);
void *p;
unsigned long *map;
bitmap_zero(map, page->objects);
get_map(s, page, map);
map = get_map(s, page);
for_each_object(p, s, addr, page->objects)
if (!test_bit(slab_index(p, s, addr), map))
add_location(t, s, get_track(s, p, alloc));
put_map(map);
}
static int list_locations(struct kmem_cache *s, char *buf,
@ -4612,11 +4621,9 @@ static int list_locations(struct kmem_cache *s, char *buf,
struct loc_track t = { 0, 0, NULL };
int node;
struct kmem_cache_node *n;
unsigned long *map = bitmap_alloc(oo_objects(s->max), GFP_KERNEL);
if (!map || !alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location),
GFP_KERNEL)) {
bitmap_free(map);
if (!alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location),
GFP_KERNEL)) {
return sprintf(buf, "Out of memory\n");
}
/* Push back cpu slabs */
@ -4631,9 +4638,9 @@ static int list_locations(struct kmem_cache *s, char *buf,
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry(page, &n->partial, slab_list)
process_slab(&t, s, page, alloc, map);
process_slab(&t, s, page, alloc);
list_for_each_entry(page, &n->full, slab_list)
process_slab(&t, s, page, alloc, map);
process_slab(&t, s, page, alloc);
spin_unlock_irqrestore(&n->list_lock, flags);
}
@ -4682,7 +4689,6 @@ static int list_locations(struct kmem_cache *s, char *buf,
}
free_loc_track(&t);
bitmap_free(map);
if (!t.count)
len += sprintf(buf, "No data\n");
return len;