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authorVlastimil Babka <vbabka@suse.cz>2021-05-23 01:28:37 +0200
committerVlastimil Babka <vbabka@suse.cz>2021-09-03 23:56:49 +0200
commitb3fd64e1451b5efd94aa0ebc755e02558e6f3ca1 (patch)
tree552e3eedc791d3d040779bd9184469afb7cf1d27
parentmm, slub: don't call flush_all() from slab_debug_trace_open() (diff)
downloadlinux-b3fd64e1451b5efd94aa0ebc755e02558e6f3ca1.tar.xz
linux-b3fd64e1451b5efd94aa0ebc755e02558e6f3ca1.zip
mm, slub: allocate private object map for debugfs listings
Slub has a static spinlock protected bitmap for marking which objects are on freelist when it wants to list them, for situations where dynamically allocating such map can lead to recursion or locking issues, and on-stack bitmap would be too large. The handlers of debugfs files alloc_traces and free_traces also currently use this shared bitmap, but their syscall context makes it straightforward to allocate a private map before entering locked sections, so switch these processing paths to use a private bitmap. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: Mel Gorman <mgorman@techsingularity.net>
-rw-r--r--mm/slub.c44
1 files changed, 29 insertions, 15 deletions
diff --git a/mm/slub.c b/mm/slub.c
index f6063ec97a55..fb603fdf58cb 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -454,6 +454,18 @@ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)];
static DEFINE_SPINLOCK(object_map_lock);
+static void __fill_map(unsigned long *obj_map, struct kmem_cache *s,
+ struct page *page)
+{
+ void *addr = page_address(page);
+ void *p;
+
+ bitmap_zero(obj_map, page->objects);
+
+ for (p = page->freelist; p; p = get_freepointer(s, p))
+ set_bit(__obj_to_index(s, addr, p), obj_map);
+}
+
#if IS_ENABLED(CONFIG_KUNIT)
static bool slab_add_kunit_errors(void)
{
@@ -483,17 +495,11 @@ static inline bool slab_add_kunit_errors(void) { return false; }
static unsigned long *get_map(struct kmem_cache *s, struct page *page)
__acquires(&object_map_lock)
{
- 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(__obj_to_index(s, addr, p), object_map);
+ __fill_map(object_map, s, page);
return object_map;
}
@@ -4879,17 +4885,17 @@ 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)
+ struct page *page, enum track_item alloc,
+ unsigned long *obj_map)
{
void *addr = page_address(page);
void *p;
- unsigned long *map;
- map = get_map(s, page);
+ __fill_map(obj_map, s, page);
+
for_each_object(p, s, addr, page->objects)
- if (!test_bit(__obj_to_index(s, addr, p), map))
+ if (!test_bit(__obj_to_index(s, addr, p), obj_map))
add_location(t, s, get_track(s, p, alloc));
- put_map(map);
}
#endif /* CONFIG_DEBUG_FS */
#endif /* CONFIG_SLUB_DEBUG */
@@ -5816,14 +5822,21 @@ static int slab_debug_trace_open(struct inode *inode, struct file *filep)
struct loc_track *t = __seq_open_private(filep, &slab_debugfs_sops,
sizeof(struct loc_track));
struct kmem_cache *s = file_inode(filep)->i_private;
+ unsigned long *obj_map;
+
+ obj_map = bitmap_alloc(oo_objects(s->oo), GFP_KERNEL);
+ if (!obj_map)
+ return -ENOMEM;
if (strcmp(filep->f_path.dentry->d_name.name, "alloc_traces") == 0)
alloc = TRACK_ALLOC;
else
alloc = TRACK_FREE;
- if (!alloc_loc_track(t, PAGE_SIZE / sizeof(struct location), GFP_KERNEL))
+ if (!alloc_loc_track(t, PAGE_SIZE / sizeof(struct location), GFP_KERNEL)) {
+ bitmap_free(obj_map);
return -ENOMEM;
+ }
for_each_kmem_cache_node(s, node, n) {
unsigned long flags;
@@ -5834,12 +5847,13 @@ static int slab_debug_trace_open(struct inode *inode, struct file *filep)
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry(page, &n->partial, slab_list)
- process_slab(t, s, page, alloc);
+ process_slab(t, s, page, alloc, obj_map);
list_for_each_entry(page, &n->full, slab_list)
- process_slab(t, s, page, alloc);
+ process_slab(t, s, page, alloc, obj_map);
spin_unlock_irqrestore(&n->list_lock, flags);
}
+ bitmap_free(obj_map);
return 0;
}