Merge tag 'slab-for-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab

Pull slab updates from Vlastimil Babka:

- Conversion of slub_debug stack traces to stackdepot, allowing more
useful debugfs-based inspection for e.g. memory leak debugging.
Allocation and free debugfs info now includes full traces and is
sorted by the unique trace frequency.

The stackdepot conversion was already attempted last year but
reverted by ae14c63a9f20. The memory overhead (while not actually
enabled on boot) has been meanwhile solved by making the large
stackdepot allocation dynamic. The xfstest issues haven't been
reproduced on current kernel locally nor in -next, so the slab cache
layout changes that originally made that bug manifest were probably
not the root cause.

- Refactoring of dma-kmalloc caches creation.

- Trivial cleanups such as removal of unused parameters, fixes and
clarifications of comments.

- Hyeonggon Yoo joins as a reviewer.

* tag 'slab-for-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
MAINTAINERS: add myself as reviewer for slab
mm/slub: remove unused kmem_cache_order_objects max
mm: slab: fix comment for __assume_kmalloc_alignment
mm: slab: fix comment for ARCH_KMALLOC_MINALIGN
mm/slub: remove unneeded return value of slab_pad_check
mm/slab_common: move dma-kmalloc caches creation into new_kmalloc_cache()
mm/slub: remove meaningless node check in ___slab_alloc()
mm/slub: remove duplicate flag in allocate_slab()
mm/slub: remove unused parameter in setup_object*()
mm/slab.c: fix comments
slab, documentation: add description of debugfs files for SLUB caches
mm/slub: sort debugfs output by frequency of stack traces
mm/slub: distinguish and print stack traces in debugfs files
mm/slub: use stackdepot to save stack trace in objects
mm/slub: move struct track init out of set_track()
lib/stackdepot: allow requesting early initialization dynamically
mm/slub, kunit: Make slub_kunit unaffected by user specified flags
mm/slab: remove some unused functions

Documentation/vm/slub.rst

···
       40,60`` range will plot only samples collected between 40th and
       60th seconds).
 
+
+DebugFS files for SLUB
+======================
+
+For more information about current state of SLUB caches with the user tracking
+debug option enabled, debugfs files are available, typically under
+/sys/kernel/debug/slab/<cache>/ (created only for caches with enabled user
+tracking). There are 2 types of these files with the following debug
+information:
+
+1. alloc_traces::
+
+    Prints information about unique allocation traces of the currently
+    allocated objects. The output is sorted by frequency of each trace.
+
+    Information in the output:
+    Number of objects, allocating function, minimal/average/maximal jiffies since alloc,
+    pid range of the allocating processes, cpu mask of allocating cpus, and stack trace.
+
+    Example:::
+
+    1085 populate_error_injection_list+0x97/0x110 age=166678/166680/166682 pid=1 cpus=1::
+	__slab_alloc+0x6d/0x90
+	kmem_cache_alloc_trace+0x2eb/0x300
+	populate_error_injection_list+0x97/0x110
+	init_error_injection+0x1b/0x71
+	do_one_initcall+0x5f/0x2d0
+	kernel_init_freeable+0x26f/0x2d7
+	kernel_init+0xe/0x118
+	ret_from_fork+0x22/0x30
+
+
+2. free_traces::
+
+    Prints information about unique freeing traces of the currently allocated
+    objects. The freeing traces thus come from the previous life-cycle of the
+    objects and are reported as not available for objects allocated for the first
+    time. The output is sorted by frequency of each trace.
+
+    Information in the output:
+    Number of objects, freeing function, minimal/average/maximal jiffies since free,
+    pid range of the freeing processes, cpu mask of freeing cpus, and stack trace.
+
+    Example:::
+
+    1980 <not-available> age=4294912290 pid=0 cpus=0
+    51 acpi_ut_update_ref_count+0x6a6/0x782 age=236886/237027/237772 pid=1 cpus=1
+	kfree+0x2db/0x420
+	acpi_ut_update_ref_count+0x6a6/0x782
+	acpi_ut_update_object_reference+0x1ad/0x234
+	acpi_ut_remove_reference+0x7d/0x84
+	acpi_rs_get_prt_method_data+0x97/0xd6
+	acpi_get_irq_routing_table+0x82/0xc4
+	acpi_pci_irq_find_prt_entry+0x8e/0x2e0
+	acpi_pci_irq_lookup+0x3a/0x1e0
+	acpi_pci_irq_enable+0x77/0x240
+	pcibios_enable_device+0x39/0x40
+	do_pci_enable_device.part.0+0x5d/0xe0
+	pci_enable_device_flags+0xfc/0x120
+	pci_enable_device+0x13/0x20
+	virtio_pci_probe+0x9e/0x170
+	local_pci_probe+0x48/0x80
+	pci_device_probe+0x105/0x1c0
+
 Christoph Lameter, May 30, 2007
 Sergey Senozhatsky, October 23, 2015

MAINTAINERS

···
 M:	Andrew Morton <[e-mail]>
 M:	Vlastimil Babka <[e-mail]>
 R:	Roman Gushchin <[e-mail]>
+R:	Hyeonggon Yoo <[e-mail]>
 L:	[e-mail]
 S:	Maintained
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab.git

include/linux/slab.h

···
 #define SLAB_KASAN		0
 #endif
 
+/*
+ * Ignore user specified debugging flags.
+ * Intended for caches created for self-tests so they have only flags
+ * specified in the code and other flags are ignored.
+ */
+#define SLAB_NO_USER_FLAGS	((slab_flags_t __force)0x10000000U)
+
 /* The following flags affect the page allocator grouping pages by mobility */
 /* Objects are reclaimable */
 #define SLAB_RECLAIM_ACCOUNT	((slab_flags_t __force)0x00020000U)
···
 /*
  * Some archs want to perform DMA into kmalloc caches and need a guaranteed
  * alignment larger than the alignment of a 64-bit integer.
- * Setting ARCH_KMALLOC_MINALIGN in arch headers allows that.
+ * Setting ARCH_DMA_MINALIGN in arch headers allows that.
  */
 #if defined(ARCH_DMA_MINALIGN) && ARCH_DMA_MINALIGN > 8
 #define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
···
 #endif
 
 /*
- * kmalloc and friends return ARCH_KMALLOC_MINALIGN aligned
- * pointers. kmem_cache_alloc and friends return ARCH_SLAB_MINALIGN
- * aligned pointers.
+ * kmem_cache_alloc and friends return pointers aligned to ARCH_SLAB_MINALIGN.
+ * kmalloc and friends return pointers aligned to both ARCH_KMALLOC_MINALIGN
+ * and ARCH_SLAB_MINALIGN, but here we only assume the former alignment.
  */
 #define __assume_kmalloc_alignment __assume_aligned(ARCH_KMALLOC_MINALIGN)
 #define __assume_slab_alignment __assume_aligned(ARCH_SLAB_MINALIGN)

include/linux/slub_def.h

···
 	struct kmem_cache_order_objects oo;
 
 	/* Allocation and freeing of slabs */
-	struct kmem_cache_order_objects max;
 	struct kmem_cache_order_objects min;
 	gfp_t allocflags;	/* gfp flags to use on each alloc */
 	int refcount;		/* Refcount for slab cache destroy */

include/linux/stackdepot.h

···
 					gfp_t gfp_flags, bool can_alloc);
 
 /*
- * Every user of stack depot has to call this during its own init when it's
- * decided that it will be calling stack_depot_save() later.
+ * Every user of stack depot has to call stack_depot_init() during its own init
+ * when it's decided that it will be calling stack_depot_save() later. This is
+ * recommended for e.g. modules initialized later in the boot process, when
+ * slab_is_available() is true.
  *
  * The alternative is to select STACKDEPOT_ALWAYS_INIT to have stack depot
  * enabled as part of mm_init(), for subsystems where it's known at compile time
  * that stack depot will be used.
+ *
+ * Another alternative is to call stack_depot_want_early_init(), when the
+ * decision to use stack depot is taken e.g. when evaluating kernel boot
+ * parameters, which precedes the enablement point in mm_init().
+ *
+ * stack_depot_init() and stack_depot_want_early_init() can be called regardless
+ * of CONFIG_STACKDEPOT and are no-op when disabled. The actual save/fetch/print
+ * functions should only be called from code that makes sure CONFIG_STACKDEPOT
+ * is enabled.
  */
+#ifdef CONFIG_STACKDEPOT
 int stack_depot_init(void);
 
-#ifdef CONFIG_STACKDEPOT_ALWAYS_INIT
-static inline int stack_depot_early_init(void)	{ return stack_depot_init(); }
+void __init stack_depot_want_early_init(void);
+
+/* This is supposed to be called only from mm_init() */
+int __init stack_depot_early_init(void);
 #else
+static inline int stack_depot_init(void) { return 0; }
+
+static inline void stack_depot_want_early_init(void) { }
+
 static inline int stack_depot_early_init(void)	{ return 0; }
 #endif
 

init/Kconfig

···
 	default y
 	bool "Enable SLUB debugging support" if EXPERT
 	depends on SLUB && SYSFS
+	select STACKDEPOT if STACKTRACE_SUPPORT
 	help
 	  SLUB has extensive debug support features. Disabling these can
 	  result in significant savings in code size. This also disables

lib/Kconfig.debug

···
 config SLUB_DEBUG_ON
 	bool "SLUB debugging on by default"
 	depends on SLUB && SLUB_DEBUG
+	select STACKDEPOT_ALWAYS_INIT if STACKTRACE_SUPPORT
 	default n
 	help
 	  Boot with debugging on by default. SLUB boots by default with

lib/slub_kunit.c

···
 static void test_clobber_zone(struct kunit *test)
 {
 	struct kmem_cache *s = kmem_cache_create("TestSlub_RZ_alloc", 64, 0,
-				SLAB_RED_ZONE, NULL);
+				SLAB_RED_ZONE|SLAB_NO_USER_FLAGS, NULL);
 	u8 *p = kmem_cache_alloc(s, GFP_KERNEL);
 
 	kasan_disable_current();
···
 static void test_next_pointer(struct kunit *test)
 {
 	struct kmem_cache *s = kmem_cache_create("TestSlub_next_ptr_free", 64, 0,
-				SLAB_POISON, NULL);
+				SLAB_POISON|SLAB_NO_USER_FLAGS, NULL);
 	u8 *p = kmem_cache_alloc(s, GFP_KERNEL);
 	unsigned long tmp;
 	unsigned long *ptr_addr;
···
 static void test_first_word(struct kunit *test)
 {
 	struct kmem_cache *s = kmem_cache_create("TestSlub_1th_word_free", 64, 0,
-				SLAB_POISON, NULL);
+				SLAB_POISON|SLAB_NO_USER_FLAGS, NULL);
 	u8 *p = kmem_cache_alloc(s, GFP_KERNEL);
 
 	kmem_cache_free(s, p);
···
 static void test_clobber_50th_byte(struct kunit *test)
 {
 	struct kmem_cache *s = kmem_cache_create("TestSlub_50th_word_free", 64, 0,
-				SLAB_POISON, NULL);
+				SLAB_POISON|SLAB_NO_USER_FLAGS, NULL);
 	u8 *p = kmem_cache_alloc(s, GFP_KERNEL);
 
 	kmem_cache_free(s, p);
···
 static void test_clobber_redzone_free(struct kunit *test)
 {
 	struct kmem_cache *s = kmem_cache_create("TestSlub_RZ_free", 64, 0,
-				SLAB_RED_ZONE, NULL);
+				SLAB_RED_ZONE|SLAB_NO_USER_FLAGS, NULL);
 	u8 *p = kmem_cache_alloc(s, GFP_KERNEL);
 
 	kasan_disable_current();

lib/stackdepot.c

···
 	unsigned long entries[];	/* Variable-sized array of entries. */
 };
 
+static bool __stack_depot_want_early_init __initdata = IS_ENABLED(CONFIG_STACKDEPOT_ALWAYS_INIT);
+static bool __stack_depot_early_init_passed __initdata;
+
 static void *stack_slabs[STACK_ALLOC_MAX_SLABS];
 
 static int depot_index;
···
 }
 early_param("stack_depot_disable", is_stack_depot_disabled);
 
-/*
- * __ref because of memblock_alloc(), which will not be actually called after
- * the __init code is gone, because at that point slab_is_available() is true
- */
-__ref int stack_depot_init(void)
+void __init stack_depot_want_early_init(void)
+{
+	/* Too late to request early init now */
+	WARN_ON(__stack_depot_early_init_passed);
+
+	__stack_depot_want_early_init = true;
+}
+
+int __init stack_depot_early_init(void)
+{
+	size_t size;
+
+	/* This is supposed to be called only once, from mm_init() */
+	if (WARN_ON(__stack_depot_early_init_passed))
+		return 0;
+
+	__stack_depot_early_init_passed = true;
+
+	if (!__stack_depot_want_early_init || stack_depot_disable)
+		return 0;
+
+	size = (STACK_HASH_SIZE * sizeof(struct stack_record *));
+	pr_info("Stack Depot early init allocating hash table with memblock_alloc, %zu bytes\n",
+		size);
+	stack_table = memblock_alloc(size, SMP_CACHE_BYTES);
+
+	if (!stack_table) {
+		pr_err("Stack Depot hash table allocation failed, disabling\n");
+		stack_depot_disable = true;
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+int stack_depot_init(void)
 {
 	static DEFINE_MUTEX(stack_depot_init_mutex);
+	int ret = 0;
 
 	mutex_lock(&stack_depot_init_mutex);
 	if (!stack_depot_disable && !stack_table) {
-		size_t size = (STACK_HASH_SIZE * sizeof(struct stack_record *));
-		int i;
-
-		if (slab_is_available()) {
-			pr_info("Stack Depot allocating hash table with kvmalloc\n");
-			stack_table = kvmalloc(size, GFP_KERNEL);
-		} else {
-			pr_info("Stack Depot allocating hash table with memblock_alloc\n");
-			stack_table = memblock_alloc(size, SMP_CACHE_BYTES);
-		}
-		if (stack_table) {
-			for (i = 0; i < STACK_HASH_SIZE;  i++)
-				stack_table[i] = NULL;
-		} else {
+		pr_info("Stack Depot allocating hash table with kvcalloc\n");
+		stack_table = kvcalloc(STACK_HASH_SIZE, sizeof(struct stack_record *), GFP_KERNEL);
+		if (!stack_table) {
 			pr_err("Stack Depot hash table allocation failed, disabling\n");
 			stack_depot_disable = true;
-			mutex_unlock(&stack_depot_init_mutex);
-			return -ENOMEM;
+			ret = -ENOMEM;
 		}
 	}
 	mutex_unlock(&stack_depot_init_mutex);
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(stack_depot_init);
 

mm/page_owner.c

···
 
 static int __init early_page_owner_param(char *buf)
 {
-	return kstrtobool(buf, &page_owner_enabled);
+	int ret = kstrtobool(buf, &page_owner_enabled);
+
+	if (page_owner_enabled)
+		stack_depot_want_early_init();
+
+	return ret;
 }
 early_param("page_owner", early_page_owner_param);
 
···
 {
 	if (!page_owner_enabled)
 		return;
-
-	stack_depot_init();
 
 	register_dummy_stack();
 	register_failure_stack();

mm/slab.c

···
 	return 0;
 }
 
-static inline void *alternate_node_alloc(struct kmem_cache *cachep,
-		gfp_t flags)
-{
-	return NULL;
-}
-
-static inline void *____cache_alloc_node(struct kmem_cache *cachep,
-		 gfp_t flags, int nodeid)
-{
-	return NULL;
-}
-
 static inline gfp_t gfp_exact_node(gfp_t flags)
 {
 	return flags & ~__GFP_NOFAIL;
 }
 
 #else	/* CONFIG_NUMA */
-
-static void *____cache_alloc_node(struct kmem_cache *, gfp_t, int);
-static void *alternate_node_alloc(struct kmem_cache *, gfp_t);
 
 static struct alien_cache *__alloc_alien_cache(int node, int entries,
 						int batch, gfp_t gfp)
···
 	int slab_node = slab_nid(virt_to_slab(objp));
 	int node = numa_mem_id();
 	/*
-	 * Make sure we are not freeing a object from another node to the array
+	 * Make sure we are not freeing an object from another node to the array
 	 * cache on this cpu.
 	 */
 	if (likely(node == slab_node))
···
 
 	/*
 	 * The kmem_cache_nodes don't come and go as CPUs
-	 * come and go.  slab_mutex is sufficient
+	 * come and go.  slab_mutex provides sufficient
 	 * protection here.
 	 */
 	cachep->node[node] = n;
···
  * Allocates and initializes node for a node on each slab cache, used for
  * either memory or cpu hotplug.  If memory is being hot-added, the kmem_cache_node
  * will be allocated off-node since memory is not yet online for the new node.
- * When hotplugging memory or a cpu, existing node are not replaced if
+ * When hotplugging memory or a cpu, existing nodes are not replaced if
  * already in use.
  *
  * Must hold slab_mutex.
···
  * offline.
  *
  * Even if all the cpus of a node are down, we don't free the
- * kmem_cache_node of any cache. This to avoid a race between cpu_down, and
+ * kmem_cache_node of any cache. This is to avoid a race between cpu_down, and
  * a kmalloc allocation from another cpu for memory from the node of
  * the cpu going down.  The kmem_cache_node structure is usually allocated from
  * kmem_cache_create() and gets destroyed at kmem_cache_destroy().
···
  * @flags: SLAB flags
  *
  * Returns a ptr to the cache on success, NULL on failure.
- * Cannot be called within a int, but can be interrupted.
+ * Cannot be called within an int, but can be interrupted.
  * The @ctor is run when new pages are allocated by the cache.
  *
  * The flags are
···
 }
 
 #ifdef CONFIG_NUMA
+static void *____cache_alloc_node(struct kmem_cache *, gfp_t, int);
+
 /*
  * Try allocating on another node if PFA_SPREAD_SLAB is a mempolicy is set.
  *
···
 }
 
 /*
- * A interface to enable slab creation on nodeid
+ * An interface to enable slab creation on nodeid
  */
 static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
 				int nodeid)

mm/slab.h

···
 			  SLAB_ACCOUNT)
 #elif defined(CONFIG_SLUB)
 #define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE | SLAB_RECLAIM_ACCOUNT | \
-			  SLAB_TEMPORARY | SLAB_ACCOUNT)
+			  SLAB_TEMPORARY | SLAB_ACCOUNT | SLAB_NO_USER_FLAGS)
 #else
 #define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE)
 #endif
···
 			      SLAB_NOLEAKTRACE | \
 			      SLAB_RECLAIM_ACCOUNT | \
 			      SLAB_TEMPORARY | \
-			      SLAB_ACCOUNT)
+			      SLAB_ACCOUNT | \
+			      SLAB_NO_USER_FLAGS)
 
 bool __kmem_cache_empty(struct kmem_cache *);
 int __kmem_cache_shutdown(struct kmem_cache *);

mm/slab_common.c

···
 #include <asm/tlbflush.h>
 #include <asm/page.h>
 #include <linux/memcontrol.h>
+#include <linux/stackdepot.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/kmem.h>
···
 	 * If no slub_debug was enabled globally, the static key is not yet
 	 * enabled by setup_slub_debug(). Enable it if the cache is being
 	 * created with any of the debugging flags passed explicitly.
+	 * It's also possible that this is the first cache created with
+	 * SLAB_STORE_USER and we should init stack_depot for it.
 	 */
 	if (flags & SLAB_DEBUG_FLAGS)
 		static_branch_enable(&slub_debug_enabled);
+	if (flags & SLAB_STORE_USER)
+		stack_depot_init();
 #endif
 
 	mutex_lock(&slab_mutex);
···
 			return;
 		}
 		flags |= SLAB_ACCOUNT;
+	} else if (IS_ENABLED(CONFIG_ZONE_DMA) && (type == KMALLOC_DMA)) {
+		flags |= SLAB_CACHE_DMA;
 	}
 
 	kmalloc_caches[type][idx] = create_kmalloc_cache(
···
 	/*
 	 * Including KMALLOC_CGROUP if CONFIG_MEMCG_KMEM defined
 	 */
-	for (type = KMALLOC_NORMAL; type <= KMALLOC_RECLAIM; type++) {
+	for (type = KMALLOC_NORMAL; type < NR_KMALLOC_TYPES; type++) {
 		for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
 			if (!kmalloc_caches[type][i])
 				new_kmalloc_cache(i, type, flags);
···
 
 	/* Kmalloc array is now usable */
 	slab_state = UP;
-
-#ifdef CONFIG_ZONE_DMA
-	for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
-		struct kmem_cache *s = kmalloc_caches[KMALLOC_NORMAL][i];
-
-		if (s) {
-			kmalloc_caches[KMALLOC_DMA][i] = create_kmalloc_cache(
-				kmalloc_info[i].name[KMALLOC_DMA],
-				kmalloc_info[i].size,
-				SLAB_CACHE_DMA | flags, 0,
-				kmalloc_info[i].size);
-		}
-	}
-#endif
 }
 #endif /* !CONFIG_SLOB */
 

mm/slub.c

···
 #include <linux/cpuset.h>
 #include <linux/mempolicy.h>
 #include <linux/ctype.h>
+#include <linux/stackdepot.h>
 #include <linux/debugobjects.h>
 #include <linux/kallsyms.h>
 #include <linux/kfence.h>
···
 #include <linux/memcontrol.h>
 #include <linux/random.h>
 #include <kunit/test.h>
+#include <linux/sort.h>
 
 #include <linux/debugfs.h>
 #include <trace/events/kmem.h>
···
 #define TRACK_ADDRS_COUNT 16
 struct track {
 	unsigned long addr;	/* Called from address */
-#ifdef CONFIG_STACKTRACE
-	unsigned long addrs[TRACK_ADDRS_COUNT];	/* Called from address */
+#ifdef CONFIG_STACKDEPOT
+	depot_stack_handle_t handle;
 #endif
 	int cpu;		/* Was running on cpu */
 	int pid;		/* Pid context */
···
 	return kasan_reset_tag(p + alloc);
 }
 
-static void set_track(struct kmem_cache *s, void *object,
+static void noinline set_track(struct kmem_cache *s, void *object,
 			enum track_item alloc, unsigned long addr)
 {
 	struct track *p = get_track(s, object, alloc);
 
-	if (addr) {
-#ifdef CONFIG_STACKTRACE
-		unsigned int nr_entries;
+#ifdef CONFIG_STACKDEPOT
+	unsigned long entries[TRACK_ADDRS_COUNT];
+	unsigned int nr_entries;
 
-		metadata_access_enable();
-		nr_entries = stack_trace_save(kasan_reset_tag(p->addrs),
-					      TRACK_ADDRS_COUNT, 3);
-		metadata_access_disable();
-
-		if (nr_entries < TRACK_ADDRS_COUNT)
-			p->addrs[nr_entries] = 0;
+	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 3);
+	p->handle = stack_depot_save(entries, nr_entries, GFP_NOWAIT);
 #endif
-		p->addr = addr;
-		p->cpu = smp_processor_id();
-		p->pid = current->pid;
-		p->when = jiffies;
-	} else {
-		memset(p, 0, sizeof(struct track));
-	}
+
+	p->addr = addr;
+	p->cpu = smp_processor_id();
+	p->pid = current->pid;
+	p->when = jiffies;
 }
 
 static void init_tracking(struct kmem_cache *s, void *object)
 {
+	struct track *p;
+
 	if (!(s->flags & SLAB_STORE_USER))
 		return;
 
-	set_track(s, object, TRACK_FREE, 0UL);
-	set_track(s, object, TRACK_ALLOC, 0UL);
+	p = get_track(s, object, TRACK_ALLOC);
+	memset(p, 0, 2*sizeof(struct track));
 }
 
 static void print_track(const char *s, struct track *t, unsigned long pr_time)
 {
+	depot_stack_handle_t handle __maybe_unused;
+
 	if (!t->addr)
 		return;
 
 	pr_err("%s in %pS age=%lu cpu=%u pid=%d\n",
 	       s, (void *)t->addr, pr_time - t->when, t->cpu, t->pid);
-#ifdef CONFIG_STACKTRACE
-	{
-		int i;
-		for (i = 0; i < TRACK_ADDRS_COUNT; i++)
-			if (t->addrs[i])
-				pr_err("\t%pS\n", (void *)t->addrs[i]);
-			else
-				break;
-	}
+#ifdef CONFIG_STACKDEPOT
+	handle = READ_ONCE(t->handle);
+	if (handle)
+		stack_depot_print(handle);
+	else
+		pr_err("object allocation/free stack trace missing\n");
 #endif
 }
 
···
 }
 
 /* Check the pad bytes at the end of a slab page */
-static int slab_pad_check(struct kmem_cache *s, struct slab *slab)
+static void slab_pad_check(struct kmem_cache *s, struct slab *slab)
 {
 	u8 *start;
 	u8 *fault;
···
 	int remainder;
 
 	if (!(s->flags & SLAB_POISON))
-		return 1;
+		return;
 
 	start = slab_address(slab);
 	length = slab_size(slab);
 	end = start + length;
 	remainder = length % s->size;
 	if (!remainder)
-		return 1;
+		return;
 
 	pad = end - remainder;
 	metadata_access_enable();
 	fault = memchr_inv(kasan_reset_tag(pad), POISON_INUSE, remainder);
 	metadata_access_disable();
 	if (!fault)
-		return 1;
+		return;
 	while (end > fault && end[-1] == POISON_INUSE)
 		end--;
 
···
 	print_section(KERN_ERR, "Padding ", pad, remainder);
 
 	restore_bytes(s, "slab padding", POISON_INUSE, fault, end);
-	return 0;
 }
 
 static int check_object(struct kmem_cache *s, struct slab *slab,
···
 }
 
 /* Object debug checks for alloc/free paths */
-static void setup_object_debug(struct kmem_cache *s, struct slab *slab,
-								void *object)
+static void setup_object_debug(struct kmem_cache *s, void *object)
 {
 	if (!kmem_cache_debug_flags(s, SLAB_STORE_USER|SLAB_RED_ZONE|__OBJECT_POISON))
 		return;
···
 			global_slub_debug_changed = true;
 		} else {
 			slab_list_specified = true;
+			if (flags & SLAB_STORE_USER)
+				stack_depot_want_early_init();
 		}
 	}
 
···
 	}
 out:
 	slub_debug = global_flags;
+	if (slub_debug & SLAB_STORE_USER)
+		stack_depot_want_early_init();
 	if (slub_debug != 0 || slub_debug_string)
 		static_branch_enable(&slub_debug_enabled);
 	else
···
 	char *next_block;
 	slab_flags_t block_flags;
 	slab_flags_t slub_debug_local = slub_debug;
+
+	if (flags & SLAB_NO_USER_FLAGS)
+		return flags;
 
 	/*
 	 * If the slab cache is for debugging (e.g. kmemleak) then
···
 	return flags | slub_debug_local;
 }
 #else /* !CONFIG_SLUB_DEBUG */
-static inline void setup_object_debug(struct kmem_cache *s,
-			struct slab *slab, void *object) {}
+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) {}
 
···
 	void *head, void *tail, int bulk_cnt,
 	unsigned long addr) { return 0; }
 
-static inline int slab_pad_check(struct kmem_cache *s, struct slab *slab)
-			{ return 1; }
+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 void add_full(struct kmem_cache *s, struct kmem_cache_node *n,
···
 	return *head != NULL;
 }
 
-static void *setup_object(struct kmem_cache *s, struct slab *slab,
-				void *object)
+static void *setup_object(struct kmem_cache *s, void *object)
 {
-	setup_object_debug(s, slab, object);
+	setup_object_debug(s, object);
 	object = kasan_init_slab_obj(s, object);
 	if (unlikely(s->ctor)) {
 		kasan_unpoison_object_data(s, object);
···
 	/* First entry is used as the base of the freelist */
 	cur = next_freelist_entry(s, slab, &pos, start, page_limit,
 				freelist_count);
-	cur = setup_object(s, slab, cur);
+	cur = setup_object(s, cur);
 	slab->freelist = cur;
 
 	for (idx = 1; idx < slab->objects; idx++) {
 		next = next_freelist_entry(s, slab, &pos, start, page_limit,
 			freelist_count);
-		next = setup_object(s, slab, next);
+		next = setup_object(s, next);
 		set_freepointer(s, cur, next);
 		cur = next;
 	}
···
 	 */
 	alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY) & ~__GFP_NOFAIL;
 	if ((alloc_gfp & __GFP_DIRECT_RECLAIM) && oo_order(oo) > oo_order(s->min))
-		alloc_gfp = (alloc_gfp | __GFP_NOMEMALLOC) & ~(__GFP_RECLAIM|__GFP_NOFAIL);
+		alloc_gfp = (alloc_gfp | __GFP_NOMEMALLOC) & ~__GFP_RECLAIM;
 
 	slab = alloc_slab_page(alloc_gfp, node, oo);
 	if (unlikely(!slab)) {
···
 
 	if (!shuffle) {
 		start = fixup_red_left(s, start);
-		start = setup_object(s, slab, start);
+		start = setup_object(s, start);
 		slab->freelist = start;
 		for (idx = 0, p = start; idx < slab->objects - 1; idx++) {
 			next = p + s->size;
-			next = setup_object(s, slab, next);
+			next = setup_object(s, next);
 			set_freepointer(s, p, next);
 			p = next;
 		}
···
 		 */
 		if (!node_isset(node, slab_nodes)) {
 			node = NUMA_NO_NODE;
-			goto redo;
 		} else {
 			stat(s, ALLOC_NODE_MISMATCH);
 			goto deactivate_slab;
···
 	 */
 	s->oo = oo_make(order, size);
 	s->min = oo_make(get_order(size), size);
-	if (oo_objects(s->oo) > oo_objects(s->max))
-		s->max = s->oo;
 
 	return !!oo_objects(s->oo);
 }
···
 	objp = fixup_red_left(s, objp);
 	trackp = get_track(s, objp, TRACK_ALLOC);
 	kpp->kp_ret = (void *)trackp->addr;
-#ifdef CONFIG_STACKTRACE
-	for (i = 0; i < KS_ADDRS_COUNT && i < TRACK_ADDRS_COUNT; i++) {
-		kpp->kp_stack[i] = (void *)trackp->addrs[i];
-		if (!kpp->kp_stack[i])
-			break;
-	}
+#ifdef CONFIG_STACKDEPOT
+	{
+		depot_stack_handle_t handle;
+		unsigned long *entries;
+		unsigned int nr_entries;
 
-	trackp = get_track(s, objp, TRACK_FREE);
-	for (i = 0; i < KS_ADDRS_COUNT && i < TRACK_ADDRS_COUNT; i++) {
-		kpp->kp_free_stack[i] = (void *)trackp->addrs[i];
-		if (!kpp->kp_free_stack[i])
-			break;
+		handle = READ_ONCE(trackp->handle);
+		if (handle) {
+			nr_entries = stack_depot_fetch(handle, &entries);
+			for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++)
+				kpp->kp_stack[i] = (void *)entries[i];
+		}
+
+		trackp = get_track(s, objp, TRACK_FREE);
+		handle = READ_ONCE(trackp->handle);
+		if (handle) {
+			nr_entries = stack_depot_fetch(handle, &entries);
+			for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++)
+				kpp->kp_free_stack[i] = (void *)entries[i];
+		}
 	}
 #endif
 #endif
···
  */
 
 struct location {
+	depot_stack_handle_t handle;
 	unsigned long count;
 	unsigned long addr;
 	long long sum_time;
···
 {
 	long start, end, pos;
 	struct location *l;
-	unsigned long caddr;
+	unsigned long caddr, chandle;
 	unsigned long age = jiffies - track->when;
+	depot_stack_handle_t handle = 0;
 
+#ifdef CONFIG_STACKDEPOT
+	handle = READ_ONCE(track->handle);
+#endif
 	start = -1;
 	end = t->count;
 
···
 			break;
 
 		caddr = t->loc[pos].addr;
-		if (track->addr == caddr) {
+		chandle = t->loc[pos].handle;
+		if ((track->addr == caddr) && (handle == chandle)) {
 
 			l = &t->loc[pos];
 			l->count++;
···
 
 		if (track->addr < caddr)
 			end = pos;
+		else if (track->addr == caddr && handle < chandle)
+			end = pos;
 		else
 			start = pos;
 	}
···
 	l->max_time = age;
 	l->min_pid = track->pid;
 	l->max_pid = track->pid;
+	l->handle = handle;
 	cpumask_clear(to_cpumask(l->cpus));
 	cpumask_set_cpu(track->cpu, to_cpumask(l->cpus));
 	nodes_clear(l->nodes);
···
 			seq_printf(seq, " nodes=%*pbl",
 				 nodemask_pr_args(&l->nodes));
 
+#ifdef CONFIG_STACKDEPOT
+		{
+			depot_stack_handle_t handle;
+			unsigned long *entries;
+			unsigned int nr_entries, j;
+
+			handle = READ_ONCE(l->handle);
+			if (handle) {
+				nr_entries = stack_depot_fetch(handle, &entries);
+				seq_puts(seq, "\n");
+				for (j = 0; j < nr_entries; j++)
+					seq_printf(seq, "        %pS\n", (void *)entries[j]);
+			}
+		}
+#endif
 		seq_puts(seq, "\n");
 	}
 
···
 		return ppos;
 
 	return NULL;
+}
+
+static int cmp_loc_by_count(const void *a, const void *b, const void *data)
+{
+	struct location *loc1 = (struct location *)a;
+	struct location *loc2 = (struct location *)b;
+
+	if (loc1->count > loc2->count)
+		return -1;
+	else
+		return 1;
 }
 
 static void *slab_debugfs_start(struct seq_file *seq, loff_t *ppos)
···
 			process_slab(t, s, slab, alloc, obj_map);
 		spin_unlock_irqrestore(&n->list_lock, flags);
 	}
+
+	/* Sort locations by count */
+	sort_r(t->loc, t->count, sizeof(struct location),
+		cmp_loc_by_count, NULL, NULL);
 
 	bitmap_free(obj_map);
 	return 0;