merge mm-hotfixes-stable into mm-nonmm-stable to pick up stackdepot changes

MAINTAINERS

@@ -14111,6 +14111,17 @@ F:	mm/
 F:	tools/mm/
 F:	tools/testing/selftests/mm/
 
+MEMORY MAPPING
+M:	Andrew Morton <akpm@linux-foundation.org>
+R:	Liam R. Howlett <Liam.Howlett@oracle.com>
+R:	Vlastimil Babka <vbabka@suse.cz>
+R:	Lorenzo Stoakes <lstoakes@gmail.com>
+L:	linux-mm@kvack.org
+S:	Maintained
+W:	http://www.linux-mm.org
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
+F:	mm/mmap.c
+
 MEMORY TECHNOLOGY DEVICES (MTD)
 M:	Miquel Raynal <miquel.raynal@bootlin.com>
 M:	Richard Weinberger <richard@nod.at>

include/linux/poison.h

@@ -92,4 +92,7 @@
 /********** VFS **********/
 #define VFS_PTR_POISON ((void *)(0xF5 + POISON_POINTER_DELTA))
 
+/********** lib/stackdepot.c **********/
+#define STACK_DEPOT_POISON ((void *)(0xD390 + POISON_POINTER_DELTA))
+
 #endif

lib/stackdepot.c

@@ -22,6 +22,7 @@
 #include <linux/list.h>
 #include <linux/mm.h>
 #include <linux/mutex.h>
+#include <linux/poison.h>
 #include <linux/printk.h>
 #include <linux/rculist.h>
 #include <linux/rcupdate.h>
@@ -43,17 +44,7 @@
 #define DEPOT_OFFSET_BITS (DEPOT_POOL_ORDER + PAGE_SHIFT - DEPOT_STACK_ALIGN)
 #define DEPOT_POOL_INDEX_BITS (DEPOT_HANDLE_BITS - DEPOT_OFFSET_BITS - \
 			       STACK_DEPOT_EXTRA_BITS)
-#if IS_ENABLED(CONFIG_KMSAN) && CONFIG_STACKDEPOT_MAX_FRAMES >= 32
-/*
- * KMSAN is frequently used in fuzzing scenarios and thus saves a lot of stack
- * traces. As KMSAN does not support evicting stack traces from the stack
- * depot, the stack depot capacity might be reached quickly with large stack
- * records. Adjust the maximum number of stack depot pools for this case.
- */
-#define DEPOT_POOLS_CAP (8192 * (CONFIG_STACKDEPOT_MAX_FRAMES / 16))
-#else
 #define DEPOT_POOLS_CAP 8192
-#endif
 #define DEPOT_MAX_POOLS \
 	(((1LL << (DEPOT_POOL_INDEX_BITS)) < DEPOT_POOLS_CAP) ? \
 	 (1LL << (DEPOT_POOL_INDEX_BITS)) : DEPOT_POOLS_CAP)
@@ -93,9 +84,6 @@ struct stack_record {
 	};
 };
 
-#define DEPOT_STACK_RECORD_SIZE \
-	ALIGN(sizeof(struct stack_record), 1 << DEPOT_STACK_ALIGN)
-
 static bool stack_depot_disabled;
 static bool __stack_depot_early_init_requested __initdata = IS_ENABLED(CONFIG_STACKDEPOT_ALWAYS_INIT);
 static bool __stack_depot_early_init_passed __initdata;
@@ -121,32 +109,31 @@ static void *stack_pools[DEPOT_MAX_POOLS];
 static void *new_pool;
 /* Number of pools in stack_pools. */
 static int pools_num;
+/* Offset to the unused space in the currently used pool. */
+static size_t pool_offset = DEPOT_POOL_SIZE;
 /* Freelist of stack records within stack_pools. */
 static LIST_HEAD(free_stacks);
-/*
- * Stack depot tries to keep an extra pool allocated even before it runs out
- * of space in the currently used pool. This flag marks whether this extra pool
- * needs to be allocated. It has the value 0 when either an extra pool is not
- * yet allocated or if the limit on the number of pools is reached.
- */
-static bool new_pool_required = true;
 /* The lock must be held when performing pool or freelist modifications. */
 static DEFINE_RAW_SPINLOCK(pool_lock);
 
 /* Statistics counters for debugfs. */
 enum depot_counter_id {
-	DEPOT_COUNTER_ALLOCS,
-	DEPOT_COUNTER_FREES,
-	DEPOT_COUNTER_INUSE,
+	DEPOT_COUNTER_REFD_ALLOCS,
+	DEPOT_COUNTER_REFD_FREES,
+	DEPOT_COUNTER_REFD_INUSE,
 	DEPOT_COUNTER_FREELIST_SIZE,
+	DEPOT_COUNTER_PERSIST_COUNT,
+	DEPOT_COUNTER_PERSIST_BYTES,
 	DEPOT_COUNTER_COUNT,
 };
 static long counters[DEPOT_COUNTER_COUNT];
 static const char *const counter_names[] = {
-	[DEPOT_COUNTER_ALLOCS]		= "allocations",
-	[DEPOT_COUNTER_FREES]		= "frees",
-	[DEPOT_COUNTER_INUSE]		= "in_use",
+	[DEPOT_COUNTER_REFD_ALLOCS]	= "refcounted_allocations",
+	[DEPOT_COUNTER_REFD_FREES]	= "refcounted_frees",
+	[DEPOT_COUNTER_REFD_INUSE]	= "refcounted_in_use",
 	[DEPOT_COUNTER_FREELIST_SIZE]	= "freelist_size",
+	[DEPOT_COUNTER_PERSIST_COUNT]	= "persistent_count",
+	[DEPOT_COUNTER_PERSIST_BYTES]	= "persistent_bytes",
 };
 static_assert(ARRAY_SIZE(counter_names) == DEPOT_COUNTER_COUNT);
 
@@ -294,48 +281,52 @@ int stack_depot_init(void)
 EXPORT_SYMBOL_GPL(stack_depot_init);
 
 /*
- * Initializes new stack depot @pool, release all its entries to the freelist,
- * and update the list of pools.
+ * Initializes new stack pool, and updates the list of pools.
  */
-static void depot_init_pool(void *pool)
+static bool depot_init_pool(void **prealloc)
 {
-	int offset;
-
 	lockdep_assert_held(&pool_lock);
 
-	/* Initialize handles and link stack records into the freelist. */
-	for (offset = 0; offset <= DEPOT_POOL_SIZE - DEPOT_STACK_RECORD_SIZE;
-	     offset += DEPOT_STACK_RECORD_SIZE) {
-		struct stack_record *stack = pool + offset;
+	if (unlikely(pools_num >= DEPOT_MAX_POOLS)) {
+		/* Bail out if we reached the pool limit. */
+		WARN_ON_ONCE(pools_num > DEPOT_MAX_POOLS); /* should never happen */
+		WARN_ON_ONCE(!new_pool); /* to avoid unnecessary pre-allocation */
+		WARN_ONCE(1, "Stack depot reached limit capacity");
+		return false;
+	}
 
-		stack->handle.pool_index = pools_num;
-		stack->handle.offset = offset >> DEPOT_STACK_ALIGN;
-		stack->handle.extra = 0;
+	if (!new_pool && *prealloc) {
+		/* We have preallocated memory, use it. */
+		WRITE_ONCE(new_pool, *prealloc);
+		*prealloc = NULL;
+	}
 
-		/*
-		 * Stack traces of size 0 are never saved, and we can simply use
-		 * the size field as an indicator if this is a new unused stack
-		 * record in the freelist.
-		 */
-		stack->size = 0;
+	if (!new_pool)
+		return false; /* new_pool and *prealloc are NULL */
+
+	/* Save reference to the pool to be used by depot_fetch_stack(). */
+	stack_pools[pools_num] = new_pool;
 
-		INIT_LIST_HEAD(&stack->hash_list);
 	/*
-		 * Add to the freelist front to prioritize never-used entries:
-		 * required in case there are entries in the freelist, but their
-		 * RCU cookie still belongs to the current RCU grace period
-		 * (there can still be concurrent readers).
+	 * Stack depot tries to keep an extra pool allocated even before it runs
+	 * out of space in the currently used pool.
+	 *
+	 * To indicate that a new preallocation is needed new_pool is reset to
+	 * NULL; do not reset to NULL if we have reached the maximum number of
+	 * pools.
 	 */
-		list_add(&stack->free_list, &free_stacks);
-		counters[DEPOT_COUNTER_FREELIST_SIZE]++;
-	}
-
-	/* Save reference to the pool to be used by depot_fetch_stack(). */
-	stack_pools[pools_num] = pool;
+	if (pools_num < DEPOT_MAX_POOLS)
+		WRITE_ONCE(new_pool, NULL);
+	else
+		WRITE_ONCE(new_pool, STACK_DEPOT_POISON);
 
 	/* Pairs with concurrent READ_ONCE() in depot_fetch_stack(). */
 	WRITE_ONCE(pools_num, pools_num + 1);
 	ASSERT_EXCLUSIVE_WRITER(pools_num);
+
+	pool_offset = 0;
+
+	return true;
 }
 
 /* Keeps the preallocated memory to be used for a new stack depot pool. */
@@ -347,63 +338,51 @@ static void depot_keep_new_pool(void **prealloc)
 	 * If a new pool is already saved or the maximum number of
 	 * pools is reached, do not use the preallocated memory.
 	 */
-	if (!new_pool_required)
+	if (new_pool)
 		return;
 
-	/*
-	 * Use the preallocated memory for the new pool
-	 * as long as we do not exceed the maximum number of pools.
-	 */
-	if (pools_num < DEPOT_MAX_POOLS) {
-		new_pool = *prealloc;
+	WRITE_ONCE(new_pool, *prealloc);
 	*prealloc = NULL;
-	}
-
-	/*
-	 * At this point, either a new pool is kept or the maximum
-	 * number of pools is reached. In either case, take note that
-	 * keeping another pool is not required.
-	 */
-	WRITE_ONCE(new_pool_required, false);
 }
 
 /*
- * Try to initialize a new stack depot pool from either a previous or the
- * current pre-allocation, and release all its entries to the freelist.
+ * Try to initialize a new stack record from the current pool, a cached pool, or
+ * the current pre-allocation.
  */
-static bool depot_try_init_pool(void **prealloc)
+static struct stack_record *depot_pop_free_pool(void **prealloc, size_t size)
 {
+	struct stack_record *stack;
+	void *current_pool;
+	u32 pool_index;
+
 	lockdep_assert_held(&pool_lock);
 
-	/* Check if we have a new pool saved and use it. */
-	if (new_pool) {
-		depot_init_pool(new_pool);
-		new_pool = NULL;
+	if (pool_offset + size > DEPOT_POOL_SIZE) {
+		if (!depot_init_pool(prealloc))
+			return NULL;
+	}
 
-		/* Take note that we might need a new new_pool. */
-		if (pools_num < DEPOT_MAX_POOLS)
-			WRITE_ONCE(new_pool_required, true);
+	if (WARN_ON_ONCE(pools_num < 1))
+		return NULL;
+	pool_index = pools_num - 1;
+	current_pool = stack_pools[pool_index];
+	if (WARN_ON_ONCE(!current_pool))
+		return NULL;
 
-		return true;
-	}
+	stack = current_pool + pool_offset;
 
-	/* Bail out if we reached the pool limit. */
-	if (unlikely(pools_num >= DEPOT_MAX_POOLS)) {
-		WARN_ONCE(1, "Stack depot reached limit capacity");
-		return false;
-	}
+	/* Pre-initialize handle once. */
+	stack->handle.pool_index = pool_index;
+	stack->handle.offset = pool_offset >> DEPOT_STACK_ALIGN;
+	stack->handle.extra = 0;
+	INIT_LIST_HEAD(&stack->hash_list);
 
-	/* Check if we have preallocated memory and use it. */
-	if (*prealloc) {
-		depot_init_pool(*prealloc);
-		*prealloc = NULL;
-		return true;
-	}
+	pool_offset += size;
 
-	return false;
+	return stack;
 }
 
-/* Try to find next free usable entry. */
+/* Try to find next free usable entry from the freelist. */
 static struct stack_record *depot_pop_free(void)
 {
 	struct stack_record *stack;
@@ -420,7 +399,7 @@ static struct stack_record *depot_pop_free(void)
 	 * check the first entry.
 	 */
 	stack = list_first_entry(&free_stacks, struct stack_record, free_list);
-	if (stack->size && !poll_state_synchronize_rcu(stack->rcu_state))
+	if (!poll_state_synchronize_rcu(stack->rcu_state))
 		return NULL;
 
 	list_del(&stack->free_list);
@@ -429,48 +408,73 @@ static struct stack_record *depot_pop_free(void)
 	return stack;
 }
 
+static inline size_t depot_stack_record_size(struct stack_record *s, unsigned int nr_entries)
+{
+	const size_t used = flex_array_size(s, entries, nr_entries);
+	const size_t unused = sizeof(s->entries) - used;
+
+	WARN_ON_ONCE(sizeof(s->entries) < used);
+
+	return ALIGN(sizeof(struct stack_record) - unused, 1 << DEPOT_STACK_ALIGN);
+}
+
 /* Allocates a new stack in a stack depot pool. */
 static struct stack_record *
-depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc)
+depot_alloc_stack(unsigned long *entries, unsigned int nr_entries, u32 hash, depot_flags_t flags, void **prealloc)
 {
-	struct stack_record *stack;
+	struct stack_record *stack = NULL;
+	size_t record_size;
 
 	lockdep_assert_held(&pool_lock);
 
 	/* This should already be checked by public API entry points. */
-	if (WARN_ON_ONCE(!size))
+	if (WARN_ON_ONCE(!nr_entries))
 		return NULL;
 
-	/* Check if we have a stack record to save the stack trace. */
+	/* Limit number of saved frames to CONFIG_STACKDEPOT_MAX_FRAMES. */
+	if (nr_entries > CONFIG_STACKDEPOT_MAX_FRAMES)
+		nr_entries = CONFIG_STACKDEPOT_MAX_FRAMES;
+
+	if (flags & STACK_DEPOT_FLAG_GET) {
+		/*
+		 * Evictable entries have to allocate the max. size so they may
+		 * safely be re-used by differently sized allocations.
+		 */
+		record_size = depot_stack_record_size(stack, CONFIG_STACKDEPOT_MAX_FRAMES);
 		stack = depot_pop_free();
+	} else {
+		record_size = depot_stack_record_size(stack, nr_entries);
+	}
+
 	if (!stack) {
-		/* No usable entries on the freelist - try to refill the freelist. */
-		if (!depot_try_init_pool(prealloc))
-			return NULL;
-		stack = depot_pop_free();
-		if (WARN_ON(!stack))
+		stack = depot_pop_free_pool(prealloc, record_size);
+		if (!stack)
 			return NULL;
 	}
 
-	/* Limit number of saved frames to CONFIG_STACKDEPOT_MAX_FRAMES. */
-	if (size > CONFIG_STACKDEPOT_MAX_FRAMES)
-		size = CONFIG_STACKDEPOT_MAX_FRAMES;
-
 	/* Save the stack trace. */
 	stack->hash = hash;
-	stack->size = size;
-	/* stack->handle is already filled in by depot_init_pool(). */
+	stack->size = nr_entries;
+	/* stack->handle is already filled in by depot_pop_free_pool(). */
+	memcpy(stack->entries, entries, flex_array_size(stack, entries, nr_entries));
+
+	if (flags & STACK_DEPOT_FLAG_GET) {
 		refcount_set(&stack->count, 1);
-	memcpy(stack->entries, entries, flex_array_size(stack, entries, size));
+		counters[DEPOT_COUNTER_REFD_ALLOCS]++;
+		counters[DEPOT_COUNTER_REFD_INUSE]++;
+	} else {
+		/* Warn on attempts to switch to refcounting this entry. */
+		refcount_set(&stack->count, REFCOUNT_SATURATED);
+		counters[DEPOT_COUNTER_PERSIST_COUNT]++;
+		counters[DEPOT_COUNTER_PERSIST_BYTES] += record_size;
+	}
 
 	/*
 	 * Let KMSAN know the stored stack record is initialized. This shall
 	 * prevent false positive reports if instrumented code accesses it.
 	 */
-	kmsan_unpoison_memory(stack, DEPOT_STACK_RECORD_SIZE);
+	kmsan_unpoison_memory(stack, record_size);
 
-	counters[DEPOT_COUNTER_ALLOCS]++;
-	counters[DEPOT_COUNTER_INUSE]++;
 	return stack;
 }
 
@@ -538,8 +542,8 @@ static void depot_free_stack(struct stack_record *stack)
 	list_add_tail(&stack->free_list, &free_stacks);
 
 	counters[DEPOT_COUNTER_FREELIST_SIZE]++;
-	counters[DEPOT_COUNTER_FREES]++;
-	counters[DEPOT_COUNTER_INUSE]--;
+	counters[DEPOT_COUNTER_REFD_FREES]++;
+	counters[DEPOT_COUNTER_REFD_INUSE]--;
 
 	printk_deferred_exit();
 	raw_spin_unlock_irqrestore(&pool_lock, flags);
@@ -660,7 +664,7 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries,
 	 * Allocate memory for a new pool if required now:
 	 * we won't be able to do that under the lock.
 	 */
-	if (unlikely(can_alloc && READ_ONCE(new_pool_required))) {
+	if (unlikely(can_alloc && !READ_ONCE(new_pool))) {
 		/*
 		 * Zero out zone modifiers, as we don't have specific zone
 		 * requirements. Keep the flags related to allocation in atomic
@@ -681,7 +685,7 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries,
 	found = find_stack(bucket, entries, nr_entries, hash, depot_flags);
 	if (!found) {
 		struct stack_record *new =
-			depot_alloc_stack(entries, nr_entries, hash, &prealloc);
+			depot_alloc_stack(entries, nr_entries, hash, depot_flags, &prealloc);
 
 		if (new) {
 			/*

mm/debug_vm_pgtable.c

@@ -362,6 +362,12 @@ static void __init pud_advanced_tests(struct pgtable_debug_args *args)
 	vaddr &= HPAGE_PUD_MASK;
 
 	pud = pfn_pud(args->pud_pfn, args->page_prot);
+	/*
+	 * Some architectures have debug checks to make sure
+	 * huge pud mapping are only found with devmap entries
+	 * For now test with only devmap entries.
+	 */
+	pud = pud_mkdevmap(pud);
 	set_pud_at(args->mm, vaddr, args->pudp, pud);
 	flush_dcache_page(page);
 	pudp_set_wrprotect(args->mm, vaddr, args->pudp);
@@ -374,6 +380,7 @@ static void __init pud_advanced_tests(struct pgtable_debug_args *args)
 	WARN_ON(!pud_none(pud));
 #endif /* __PAGETABLE_PMD_FOLDED */
 	pud = pfn_pud(args->pud_pfn, args->page_prot);
+	pud = pud_mkdevmap(pud);
 	pud = pud_wrprotect(pud);
 	pud = pud_mkclean(pud);
 	set_pud_at(args->mm, vaddr, args->pudp, pud);
@@ -391,6 +398,7 @@ static void __init pud_advanced_tests(struct pgtable_debug_args *args)
 #endif /* __PAGETABLE_PMD_FOLDED */
 
 	pud = pfn_pud(args->pud_pfn, args->page_prot);
+	pud = pud_mkdevmap(pud);
 	pud = pud_mkyoung(pud);
 	set_pud_at(args->mm, vaddr, args->pudp, pud);
 	flush_dcache_page(page);

mm/filemap.c

@@ -4111,18 +4111,25 @@ static void filemap_cachestat(struct address_space *mapping,
 
 	rcu_read_lock();
 	xas_for_each(&xas, folio, last_index) {
+		int order;
 		unsigned long nr_pages;
 		pgoff_t folio_first_index, folio_last_index;
 
+		/*
+		 * Don't deref the folio. It is not pinned, and might
+		 * get freed (and reused) underneath us.
+		 *
+		 * We *could* pin it, but that would be expensive for
+		 * what should be a fast and lightweight syscall.
+		 *
+		 * Instead, derive all information of interest from
+		 * the rcu-protected xarray.
+		 */
+
 		if (xas_retry(&xas, folio))
 			continue;
 
-		if (xa_is_value(folio)) {
-			/* page is evicted */
-			void *shadow = (void *)folio;
-			bool workingset; /* not used */
-			int order = xa_get_order(xas.xa, xas.xa_index);
-
+		order = xa_get_order(xas.xa, xas.xa_index);
 		nr_pages = 1 << order;
 		folio_first_index = round_down(xas.xa_index, 1 << order);
 		folio_last_index = folio_first_index + nr_pages - 1;
@@ -4134,6 +4141,11 @@ static void filemap_cachestat(struct address_space *mapping,
 		if (folio_last_index > last_index)
 			nr_pages -= folio_last_index - last_index;
 
+		if (xa_is_value(folio)) {
+			/* page is evicted */
+			void *shadow = (void *)folio;
+			bool workingset; /* not used */
+
 			cs->nr_evicted += nr_pages;
 
 #ifdef CONFIG_SWAP /* implies CONFIG_MMU */
@@ -4150,24 +4162,13 @@ static void filemap_cachestat(struct address_space *mapping,
 			goto resched;
 		}
 
-		nr_pages = folio_nr_pages(folio);
-		folio_first_index = folio_pgoff(folio);
-		folio_last_index = folio_first_index + nr_pages - 1;
-
-		/* Folios might straddle the range boundaries, only count covered pages */
-		if (folio_first_index < first_index)
-			nr_pages -= first_index - folio_first_index;
-
-		if (folio_last_index > last_index)
-			nr_pages -= folio_last_index - last_index;
-
 		/* page is in cache */
 		cs->nr_cache += nr_pages;
 
-		if (folio_test_dirty(folio))
+		if (xas_get_mark(&xas, PAGECACHE_TAG_DIRTY))
 			cs->nr_dirty += nr_pages;
 
-		if (folio_test_writeback(folio))
+		if (xas_get_mark(&xas, PAGECACHE_TAG_WRITEBACK))
 			cs->nr_writeback += nr_pages;
 
 resched:

mm/kasan/common.c

@@ -65,8 +65,7 @@ void kasan_save_track(struct kasan_track *track, gfp_t flags)
 {
 	depot_stack_handle_t stack;
 
-	stack = kasan_save_stack(flags,
-			STACK_DEPOT_FLAG_CAN_ALLOC | STACK_DEPOT_FLAG_GET);
+	stack = kasan_save_stack(flags, STACK_DEPOT_FLAG_CAN_ALLOC);
 	kasan_set_track(track, stack);
 }
 
@@ -266,10 +265,9 @@ bool __kasan_slab_free(struct kmem_cache *cache, void *object,
 		return true;
 
 	/*
-	 * If the object is not put into quarantine, it will likely be quickly
-	 * reallocated. Thus, release its metadata now.
+	 * Note: Keep per-object metadata to allow KASAN print stack traces for
+	 * use-after-free-before-realloc bugs.
 	 */
-	kasan_release_object_meta(cache, object);
 
 	/* Let slab put the object onto the freelist. */
 	return false;

mm/kasan/generic.c

@@ -485,16 +485,6 @@ void kasan_init_object_meta(struct kmem_cache *cache, const void *object)
 	if (alloc_meta) {
 		/* Zero out alloc meta to mark it as invalid. */
 		__memset(alloc_meta, 0, sizeof(*alloc_meta));
-
-		/*
-		 * Prepare the lock for saving auxiliary stack traces.
-		 * Temporarily disable KASAN bug reporting to allow instrumented
-		 * raw_spin_lock_init to access aux_lock, which resides inside
-		 * of a redzone.
-		 */
-		kasan_disable_current();
-		raw_spin_lock_init(&alloc_meta->aux_lock);
-		kasan_enable_current();
 	}
 
 	/*
@@ -506,18 +496,8 @@ void kasan_init_object_meta(struct kmem_cache *cache, const void *object)
 
 static void release_alloc_meta(struct kasan_alloc_meta *meta)
 {
-	/* Evict the stack traces from stack depot. */
-	stack_depot_put(meta->alloc_track.stack);
-	stack_depot_put(meta->aux_stack[0]);
-	stack_depot_put(meta->aux_stack[1]);
-
-	/*
-	 * Zero out alloc meta to mark it as invalid but keep aux_lock
-	 * initialized to avoid having to reinitialize it when another object
-	 * is allocated in the same slot.
-	 */
-	__memset(&meta->alloc_track, 0, sizeof(meta->alloc_track));
-	__memset(meta->aux_stack, 0, sizeof(meta->aux_stack));
+	/* Zero out alloc meta to mark it as invalid. */
+	__memset(meta, 0, sizeof(*meta));
 }
 
 static void release_free_meta(const void *object, struct kasan_free_meta *meta)
@@ -529,27 +509,10 @@ static void release_free_meta(const void *object, struct kasan_free_meta *meta)
 	if (*(u8 *)kasan_mem_to_shadow(object) != KASAN_SLAB_FREE_META)
 		return;
 
-	/* Evict the stack trace from the stack depot. */
-	stack_depot_put(meta->free_track.stack);
-
 	/* Mark free meta as invalid. */
 	*(u8 *)kasan_mem_to_shadow(object) = KASAN_SLAB_FREE;
 }
 
-void kasan_release_object_meta(struct kmem_cache *cache, const void *object)
-{
-	struct kasan_alloc_meta *alloc_meta;
-	struct kasan_free_meta *free_meta;
-
-	alloc_meta = kasan_get_alloc_meta(cache, object);
-	if (alloc_meta)
-		release_alloc_meta(alloc_meta);
-
-	free_meta = kasan_get_free_meta(cache, object);
-	if (free_meta)
-		release_free_meta(object, free_meta);
-}
-
 size_t kasan_metadata_size(struct kmem_cache *cache, bool in_object)
 {
 	struct kasan_cache *info = &cache->kasan_info;
@@ -574,8 +537,6 @@ static void __kasan_record_aux_stack(void *addr, depot_flags_t depot_flags)
 	struct kmem_cache *cache;
 	struct kasan_alloc_meta *alloc_meta;
 	void *object;
-	depot_stack_handle_t new_handle, old_handle;
-	unsigned long flags;
 
 	if (is_kfence_address(addr) || !slab)
 		return;
@@ -586,33 +547,18 @@ static void __kasan_record_aux_stack(void *addr, depot_flags_t depot_flags)
 	if (!alloc_meta)
 		return;
 
-	new_handle = kasan_save_stack(0, depot_flags);
-
-	/*
-	 * Temporarily disable KASAN bug reporting to allow instrumented
-	 * spinlock functions to access aux_lock, which resides inside of a
-	 * redzone.
-	 */
-	kasan_disable_current();
-	raw_spin_lock_irqsave(&alloc_meta->aux_lock, flags);
-	old_handle = alloc_meta->aux_stack[1];
 	alloc_meta->aux_stack[1] = alloc_meta->aux_stack[0];
-	alloc_meta->aux_stack[0] = new_handle;
-	raw_spin_unlock_irqrestore(&alloc_meta->aux_lock, flags);
-	kasan_enable_current();
-
-	stack_depot_put(old_handle);
+	alloc_meta->aux_stack[0] = kasan_save_stack(0, depot_flags);
 }
 
 void kasan_record_aux_stack(void *addr)
 {
-	return __kasan_record_aux_stack(addr,
-			STACK_DEPOT_FLAG_CAN_ALLOC | STACK_DEPOT_FLAG_GET);
+	return __kasan_record_aux_stack(addr, STACK_DEPOT_FLAG_CAN_ALLOC);
 }
 
 void kasan_record_aux_stack_noalloc(void *addr)
 {
-	return __kasan_record_aux_stack(addr, STACK_DEPOT_FLAG_GET);
+	return __kasan_record_aux_stack(addr, 0);
 }
 
 void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
@@ -623,7 +569,7 @@ void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
 	if (!alloc_meta)
 		return;
 
-	/* Evict previous stack traces (might exist for krealloc or mempool). */
+	/* Invalidate previous stack traces (might exist for krealloc or mempool). */
 	release_alloc_meta(alloc_meta);
 
 	kasan_save_track(&alloc_meta->alloc_track, flags);
@@ -637,7 +583,7 @@ void kasan_save_free_info(struct kmem_cache *cache, void *object)
 	if (!free_meta)
 		return;
 
-	/* Evict previous stack trace (might exist for mempool). */
+	/* Invalidate previous stack trace (might exist for mempool). */
 	release_free_meta(object, free_meta);
 
 	kasan_save_track(&free_meta->free_track, 0);

mm/kasan/kasan.h

@@ -6,7 +6,6 @@
 #include <linux/kasan.h>
 #include <linux/kasan-tags.h>
 #include <linux/kfence.h>
-#include <linux/spinlock.h>
 #include <linux/stackdepot.h>
 
 #if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
@@ -265,13 +264,6 @@ struct kasan_global {
 struct kasan_alloc_meta {
 	struct kasan_track alloc_track;
 	/* Free track is stored in kasan_free_meta. */
-	/*
-	 * aux_lock protects aux_stack from accesses from concurrent
-	 * kasan_record_aux_stack calls. It is a raw spinlock to avoid sleeping
-	 * on RT kernels, as kasan_record_aux_stack_noalloc can be called from
-	 * non-sleepable contexts.
-	 */
-	raw_spinlock_t aux_lock;
 	depot_stack_handle_t aux_stack[2];
 };
 
@@ -398,10 +390,8 @@ struct kasan_alloc_meta *kasan_get_alloc_meta(struct kmem_cache *cache,
 struct kasan_free_meta *kasan_get_free_meta(struct kmem_cache *cache,
 						const void *object);
 void kasan_init_object_meta(struct kmem_cache *cache, const void *object);
-void kasan_release_object_meta(struct kmem_cache *cache, const void *object);
 #else
 static inline void kasan_init_object_meta(struct kmem_cache *cache, const void *object) { }
-static inline void kasan_release_object_meta(struct kmem_cache *cache, const void *object) { }
 #endif
 
 depot_stack_handle_t kasan_save_stack(gfp_t flags, depot_flags_t depot_flags);

mm/kasan/quarantine.c

@@ -145,7 +145,10 @@ static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
 	void *object = qlink_to_object(qlink, cache);
 	struct kasan_free_meta *free_meta = kasan_get_free_meta(cache, object);
 
-	kasan_release_object_meta(cache, object);
+	/*
+	 * Note: Keep per-object metadata to allow KASAN print stack traces for
+	 * use-after-free-before-realloc bugs.
+	 */
 
 	/*
 	 * If init_on_free is enabled and KASAN's free metadata is stored in

mm/migrate.c

@@ -2522,6 +2522,14 @@ static int numamigrate_isolate_folio(pg_data_t *pgdat, struct folio *folio)
 			if (managed_zone(pgdat->node_zones + z))
 				break;
 		}
+
+		/*
+		 * If there are no managed zones, it should not proceed
+		 * further.
+		 */
+		if (z < 0)
+			return 0;
+
 		wakeup_kswapd(pgdat->node_zones + z, 0,
 			      folio_order(folio), ZONE_MOVABLE);
 		return 0;