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mm, slub: refactor free debug processing 

Since commit c7323a5ad0 ("mm/slub: restrict sysfs validation to debug
caches and make it safe"), caches with debugging enabled use the
free_debug_processing() function to do both freeing checks and actual
freeing to partial list under list_lock, bypassing the fast paths.

We will want to use the same path for CONFIG_SLUB_TINY, but without the
debugging checks, so refactor the code so that free_debug_processing()
does only the checks, while the freeing is handled by a new function
free_to_partial_list().

For consistency, change return parameter alloc_debug_processing() from
int to bool and correct the !SLUB_DEBUG variant to return true and not
false. This didn't matter until now, but will in the following changes.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
This commit is contained in:
Vlastimil Babka 2022-11-21 16:06:38 +01:00
parent 3d97d976e5
commit fa9b88e459
1 changed files with 83 additions and 71 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

154
mm/slub.c
View File

@ -1368,7 +1368,7 @@ static inline int alloc_consistency_checks(struct kmem_cache *s,
return 1;
}
static noinline int alloc_debug_processing(struct kmem_cache *s,
static noinline bool alloc_debug_processing(struct kmem_cache *s,
struct slab *slab, void *object, int orig_size)
{
if (s->flags & SLAB_CONSISTENCY_CHECKS) {
@ -1380,7 +1380,7 @@ static noinline int alloc_debug_processing(struct kmem_cache *s,
trace(s, slab, object, 1);
set_orig_size(s, object, orig_size);
init_object(s, object, SLUB_RED_ACTIVE);
return 1;
return true;
bad:
if (folio_test_slab(slab_folio(slab))) {
@ -1393,7 +1393,7 @@ bad:
slab->inuse = slab->objects;
slab->freelist = NULL;
}
return 0;
return false;
}
static inline int free_consistency_checks(struct kmem_cache *s,
@ -1646,17 +1646,17 @@ static inline void setup_object_debug(struct kmem_cache *s, void *object) {}
static inline
void setup_slab_debug(struct kmem_cache *s, struct slab *slab, void *addr) {}
static inline int alloc_debug_processing(struct kmem_cache *s,
struct slab *slab, void *object, int orig_size) { return 0; }
static inline bool alloc_debug_processing(struct kmem_cache *s,
struct slab *slab, void *object, int orig_size) { return true; }
static inline void free_debug_processing(
struct kmem_cache *s, struct slab *slab,
void *head, void *tail, int bulk_cnt,
unsigned long addr) {}
static inline bool free_debug_processing(struct kmem_cache *s,
struct slab *slab, void *head, void *tail, int *bulk_cnt,
unsigned long addr, depot_stack_handle_t handle) { return true; }
static inline void slab_pad_check(struct kmem_cache *s, struct slab *slab) {}
static inline int check_object(struct kmem_cache *s, struct slab *slab,
void *object, u8 val) { return 1; }
static inline depot_stack_handle_t set_track_prepare(void) { return 0; }
static inline void set_track(struct kmem_cache *s, void *object,
enum track_item alloc, unsigned long addr) {}
static inline void add_full(struct kmem_cache *s, struct kmem_cache_node *n,
@ -2833,38 +2833,28 @@ static inline unsigned long node_nr_objs(struct kmem_cache_node *n)
}
/* Supports checking bulk free of a constructed freelist */
static noinline void free_debug_processing(
struct kmem_cache *s, struct slab *slab,
void *head, void *tail, int bulk_cnt,
unsigned long addr)
static inline bool free_debug_processing(struct kmem_cache *s,
struct slab *slab, void *head, void *tail, int *bulk_cnt,
unsigned long addr, depot_stack_handle_t handle)
{
struct kmem_cache_node *n = get_node(s, slab_nid(slab));
struct slab *slab_free = NULL;
bool checks_ok = false;
void *object = head;
int cnt = 0;
unsigned long flags;
bool checks_ok = false;
depot_stack_handle_t handle = 0;
if (s->flags & SLAB_STORE_USER)
handle = set_track_prepare();
spin_lock_irqsave(&n->list_lock, flags);
if (s->flags & SLAB_CONSISTENCY_CHECKS) {
if (!check_slab(s, slab))
goto out;
}
if (slab->inuse < bulk_cnt) {
if (slab->inuse < *bulk_cnt) {
slab_err(s, slab, "Slab has %d allocated objects but %d are to be freed\n",
slab->inuse, bulk_cnt);
slab->inuse, *bulk_cnt);
goto out;
}
next_object:
if (++cnt > bulk_cnt)
if (++cnt > *bulk_cnt)
goto out_cnt;
if (s->flags & SLAB_CONSISTENCY_CHECKS) {
@ -2886,57 +2876,18 @@ next_object:
checks_ok = true;
out_cnt:
if (cnt != bulk_cnt)
if (cnt != *bulk_cnt) {
slab_err(s, slab, "Bulk free expected %d objects but found %d\n",
bulk_cnt, cnt);
*bulk_cnt, cnt);
*bulk_cnt = cnt;
}
out:
if (checks_ok) {
void *prior = slab->freelist;
/* Perform the actual freeing while we still hold the locks */
slab->inuse -= cnt;
set_freepointer(s, tail, prior);
slab->freelist = head;
/*
* If the slab is empty, and node's partial list is full,
* it should be discarded anyway no matter it's on full or
* partial list.
*/
if (slab->inuse == 0 && n->nr_partial >= s->min_partial)
slab_free = slab;
if (!prior) {
/* was on full list */
remove_full(s, n, slab);
if (!slab_free) {
add_partial(n, slab, DEACTIVATE_TO_TAIL);
stat(s, FREE_ADD_PARTIAL);
}
} else if (slab_free) {
remove_partial(n, slab);
stat(s, FREE_REMOVE_PARTIAL);
}
}
if (slab_free) {
/*
* Update the counters while still holding n->list_lock to
* prevent spurious validation warnings
*/
dec_slabs_node(s, slab_nid(slab_free), slab_free->objects);
}
spin_unlock_irqrestore(&n->list_lock, flags);
if (!checks_ok)
slab_fix(s, "Object at 0x%p not freed", object);
if (slab_free) {
stat(s, FREE_SLAB);
free_slab(s, slab_free);
}
return checks_ok;
}
#endif /* CONFIG_SLUB_DEBUG */
@ -3453,6 +3404,67 @@ void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node)
}
EXPORT_SYMBOL(kmem_cache_alloc_node);
static noinline void free_to_partial_list(
struct kmem_cache *s, struct slab *slab,
void *head, void *tail, int bulk_cnt,
unsigned long addr)
{
struct kmem_cache_node *n = get_node(s, slab_nid(slab));
struct slab *slab_free = NULL;
int cnt = bulk_cnt;
unsigned long flags;
depot_stack_handle_t handle = 0;
if (s->flags & SLAB_STORE_USER)
handle = set_track_prepare();
spin_lock_irqsave(&n->list_lock, flags);
if (free_debug_processing(s, slab, head, tail, &cnt, addr, handle)) {
void *prior = slab->freelist;
/* Perform the actual freeing while we still hold the locks */
slab->inuse -= cnt;
set_freepointer(s, tail, prior);
slab->freelist = head;
/*
* If the slab is empty, and node's partial list is full,
* it should be discarded anyway no matter it's on full or
* partial list.
*/
if (slab->inuse == 0 && n->nr_partial >= s->min_partial)
slab_free = slab;
if (!prior) {
/* was on full list */
remove_full(s, n, slab);
if (!slab_free) {
add_partial(n, slab, DEACTIVATE_TO_TAIL);
stat(s, FREE_ADD_PARTIAL);
}
} else if (slab_free) {
remove_partial(n, slab);
stat(s, FREE_REMOVE_PARTIAL);
}
}
if (slab_free) {
/*
* Update the counters while still holding n->list_lock to
* prevent spurious validation warnings
*/
dec_slabs_node(s, slab_nid(slab_free), slab_free->objects);
}
spin_unlock_irqrestore(&n->list_lock, flags);
if (slab_free) {
stat(s, FREE_SLAB);
free_slab(s, slab_free);
}
}
/*
* Slow path handling. This may still be called frequently since objects
* have a longer lifetime than the cpu slabs in most processing loads.
@ -3479,7 +3491,7 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab,
return;
if (kmem_cache_debug(s)) {
free_debug_processing(s, slab, head, tail, cnt, addr);
free_to_partial_list(s, slab, head, tail, cnt, addr);
return;
}