diff --git a/include/linux/kcsan-checks.h b/include/linux/kcsan-checks.h
index 5f5965246877..a1c6a89fde71 100644
--- a/include/linux/kcsan-checks.h
+++ b/include/linux/kcsan-checks.h
@@ -99,7 +99,15 @@ void kcsan_set_access_mask(unsigned long mask);
 
 /* Scoped access information. */
 struct kcsan_scoped_access {
-	struct list_head list;
+	union {
+		struct list_head list; /* scoped_accesses list */
+		/*
+		 * Not an entry in scoped_accesses list; stack depth from where
+		 * the access was initialized.
+		 */
+		int stack_depth;
+	};
+
 	/* Access information. */
 	const volatile void *ptr;
 	size_t size;
diff --git a/include/linux/kcsan.h b/include/linux/kcsan.h
index 13cef3458fed..c07c71f5ba4f 100644
--- a/include/linux/kcsan.h
+++ b/include/linux/kcsan.h
@@ -49,8 +49,16 @@ struct kcsan_ctx {
 	 */
 	unsigned long access_mask;
 
-	/* List of scoped accesses. */
+	/* List of scoped accesses; likely to be empty. */
 	struct list_head scoped_accesses;
+
+#ifdef CONFIG_KCSAN_WEAK_MEMORY
+	/*
+	 * Scoped access for modeling access reordering to detect missing memory
+	 * barriers; only keep 1 to keep fast-path complexity manageable.
+	 */
+	struct kcsan_scoped_access reorder_access;
+#endif
 };
 
 /**
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 78c351e35fec..0cd40b010487 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1339,6 +1339,9 @@ struct task_struct {
 #ifdef CONFIG_TRACE_IRQFLAGS
 	struct irqtrace_events		kcsan_save_irqtrace;
 #endif
+#ifdef CONFIG_KCSAN_WEAK_MEMORY
+	int				kcsan_stack_depth;
+#endif
 #endif
 
 #if IS_ENABLED(CONFIG_KUNIT)
diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c
index bd359f8ee63a..24d82baa807d 100644
--- a/kernel/kcsan/core.c
+++ b/kernel/kcsan/core.c
@@ -12,6 +12,7 @@
 #include <linux/delay.h>
 #include <linux/export.h>
 #include <linux/init.h>
+#include <linux/instrumentation.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/moduleparam.h>
@@ -20,6 +21,8 @@
 #include <linux/sched.h>
 #include <linux/uaccess.h>
 
+#include <asm/sections.h>
+
 #include "encoding.h"
 #include "kcsan.h"
 #include "permissive.h"
@@ -29,6 +32,7 @@ unsigned int kcsan_udelay_task = CONFIG_KCSAN_UDELAY_TASK;
 unsigned int kcsan_udelay_interrupt = CONFIG_KCSAN_UDELAY_INTERRUPT;
 static long kcsan_skip_watch = CONFIG_KCSAN_SKIP_WATCH;
 static bool kcsan_interrupt_watcher = IS_ENABLED(CONFIG_KCSAN_INTERRUPT_WATCHER);
+static bool kcsan_weak_memory = IS_ENABLED(CONFIG_KCSAN_WEAK_MEMORY);
 
 #ifdef MODULE_PARAM_PREFIX
 #undef MODULE_PARAM_PREFIX
@@ -39,6 +43,9 @@ module_param_named(udelay_task, kcsan_udelay_task, uint, 0644);
 module_param_named(udelay_interrupt, kcsan_udelay_interrupt, uint, 0644);
 module_param_named(skip_watch, kcsan_skip_watch, long, 0644);
 module_param_named(interrupt_watcher, kcsan_interrupt_watcher, bool, 0444);
+#ifdef CONFIG_KCSAN_WEAK_MEMORY
+module_param_named(weak_memory, kcsan_weak_memory, bool, 0644);
+#endif
 
 bool kcsan_enabled;
 
@@ -102,6 +109,22 @@ static DEFINE_PER_CPU(long, kcsan_skip);
 /* For kcsan_prandom_u32_max(). */
 static DEFINE_PER_CPU(u32, kcsan_rand_state);
 
+#if !defined(CONFIG_ARCH_WANTS_NO_INSTR) || defined(CONFIG_STACK_VALIDATION)
+/*
+ * Arch does not rely on noinstr, or objtool will remove memory barrier
+ * instrumentation, and no instrumentation of noinstr code is expected.
+ */
+#define kcsan_noinstr noinline
+static inline bool within_noinstr(unsigned long ip) { return false; }
+#else
+#define kcsan_noinstr noinstr
+static __always_inline bool within_noinstr(unsigned long ip)
+{
+	return (unsigned long)__noinstr_text_start <= ip &&
+	       ip < (unsigned long)__noinstr_text_end;
+}
+#endif
+
 static __always_inline atomic_long_t *find_watchpoint(unsigned long addr,
 						      size_t size,
 						      bool expect_write,
@@ -351,6 +374,67 @@ void kcsan_restore_irqtrace(struct task_struct *task)
 #endif
 }
 
+static __always_inline int get_kcsan_stack_depth(void)
+{
+#ifdef CONFIG_KCSAN_WEAK_MEMORY
+	return current->kcsan_stack_depth;
+#else
+	BUILD_BUG();
+	return 0;
+#endif
+}
+
+static __always_inline void add_kcsan_stack_depth(int val)
+{
+#ifdef CONFIG_KCSAN_WEAK_MEMORY
+	current->kcsan_stack_depth += val;
+#else
+	BUILD_BUG();
+#endif
+}
+
+static __always_inline struct kcsan_scoped_access *get_reorder_access(struct kcsan_ctx *ctx)
+{
+#ifdef CONFIG_KCSAN_WEAK_MEMORY
+	return ctx->disable_scoped ? NULL : &ctx->reorder_access;
+#else
+	return NULL;
+#endif
+}
+
+static __always_inline bool
+find_reorder_access(struct kcsan_ctx *ctx, const volatile void *ptr, size_t size,
+		    int type, unsigned long ip)
+{
+	struct kcsan_scoped_access *reorder_access = get_reorder_access(ctx);
+
+	if (!reorder_access)
+		return false;
+
+	/*
+	 * Note: If accesses are repeated while reorder_access is identical,
+	 * never matches the new access, because !(type & KCSAN_ACCESS_SCOPED).
+	 */
+	return reorder_access->ptr == ptr && reorder_access->size == size &&
+	       reorder_access->type == type && reorder_access->ip == ip;
+}
+
+static inline void
+set_reorder_access(struct kcsan_ctx *ctx, const volatile void *ptr, size_t size,
+		   int type, unsigned long ip)
+{
+	struct kcsan_scoped_access *reorder_access = get_reorder_access(ctx);
+
+	if (!reorder_access || !kcsan_weak_memory)
+		return;
+
+	reorder_access->ptr		= ptr;
+	reorder_access->size		= size;
+	reorder_access->type		= type | KCSAN_ACCESS_SCOPED;
+	reorder_access->ip		= ip;
+	reorder_access->stack_depth	= get_kcsan_stack_depth();
+}
+
 /*
  * Pull everything together: check_access() below contains the performance
  * critical operations; the fast-path (including check_access) functions should
@@ -389,8 +473,10 @@ static noinline void kcsan_found_watchpoint(const volatile void *ptr,
 	 * The access_mask check relies on value-change comparison. To avoid
 	 * reporting a race where e.g. the writer set up the watchpoint, but the
 	 * reader has access_mask!=0, we have to ignore the found watchpoint.
+	 *
+	 * reorder_access is never created from an access with access_mask set.
 	 */
-	if (ctx->access_mask)
+	if (ctx->access_mask && !find_reorder_access(ctx, ptr, size, type, ip))
 		return;
 
 	/*
@@ -440,11 +526,13 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned
 	const bool is_assert = (type & KCSAN_ACCESS_ASSERT) != 0;
 	atomic_long_t *watchpoint;
 	u64 old, new, diff;
-	unsigned long access_mask;
 	enum kcsan_value_change value_change = KCSAN_VALUE_CHANGE_MAYBE;
+	bool interrupt_watcher = kcsan_interrupt_watcher;
 	unsigned long ua_flags = user_access_save();
 	struct kcsan_ctx *ctx = get_ctx();
+	unsigned long access_mask = ctx->access_mask;
 	unsigned long irq_flags = 0;
+	bool is_reorder_access;
 
 	/*
 	 * Always reset kcsan_skip counter in slow-path to avoid underflow; see
@@ -467,6 +555,17 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned
 		goto out;
 	}
 
+	/*
+	 * The local CPU cannot observe reordering of its own accesses, and
+	 * therefore we need to take care of 2 cases to avoid false positives:
+	 *
+	 *	1. Races of the reordered access with interrupts. To avoid, if
+	 *	   the current access is reorder_access, disable interrupts.
+	 *	2. Avoid races of scoped accesses from nested interrupts (below).
+	 */
+	is_reorder_access = find_reorder_access(ctx, ptr, size, type, ip);
+	if (is_reorder_access)
+		interrupt_watcher = false;
 	/*
 	 * Avoid races of scoped accesses from nested interrupts (or scheduler).
 	 * Assume setting up a watchpoint for a non-scoped (normal) access that
@@ -482,7 +581,7 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned
 	 * information is lost if dirtied by KCSAN.
 	 */
 	kcsan_save_irqtrace(current);
-	if (!kcsan_interrupt_watcher)
+	if (!interrupt_watcher)
 		local_irq_save(irq_flags);
 
 	watchpoint = insert_watchpoint((unsigned long)ptr, size, is_write);
@@ -503,7 +602,7 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned
 	 * Read the current value, to later check and infer a race if the data
 	 * was modified via a non-instrumented access, e.g. from a device.
 	 */
-	old = read_instrumented_memory(ptr, size);
+	old = is_reorder_access ? 0 : read_instrumented_memory(ptr, size);
 
 	/*
 	 * Delay this thread, to increase probability of observing a racy
@@ -515,8 +614,17 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned
 	 * Re-read value, and check if it is as expected; if not, we infer a
 	 * racy access.
 	 */
-	access_mask = ctx->access_mask;
-	new = read_instrumented_memory(ptr, size);
+	if (!is_reorder_access) {
+		new = read_instrumented_memory(ptr, size);
+	} else {
+		/*
+		 * Reordered accesses cannot be used for value change detection,
+		 * because the memory location may no longer be accessible and
+		 * could result in a fault.
+		 */
+		new = 0;
+		access_mask = 0;
+	}
 
 	diff = old ^ new;
 	if (access_mask)
@@ -585,11 +693,20 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned
 	 */
 	remove_watchpoint(watchpoint);
 	atomic_long_dec(&kcsan_counters[KCSAN_COUNTER_USED_WATCHPOINTS]);
+
 out_unlock:
-	if (!kcsan_interrupt_watcher)
+	if (!interrupt_watcher)
 		local_irq_restore(irq_flags);
 	kcsan_restore_irqtrace(current);
 	ctx->disable_scoped--;
+
+	/*
+	 * Reordered accesses cannot be used for value change detection,
+	 * therefore never consider for reordering if access_mask is set.
+	 * ASSERT_EXCLUSIVE are not real accesses, ignore them as well.
+	 */
+	if (!access_mask && !is_assert)
+		set_reorder_access(ctx, ptr, size, type, ip);
 out:
 	user_access_restore(ua_flags);
 }
@@ -597,7 +714,6 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned
 static __always_inline void
 check_access(const volatile void *ptr, size_t size, int type, unsigned long ip)
 {
-	const bool is_write = (type & KCSAN_ACCESS_WRITE) != 0;
 	atomic_long_t *watchpoint;
 	long encoded_watchpoint;
 
@@ -608,12 +724,14 @@ check_access(const volatile void *ptr, size_t size, int type, unsigned long ip)
 	if (unlikely(size == 0))
 		return;
 
+again:
 	/*
 	 * Avoid user_access_save in fast-path: find_watchpoint is safe without
 	 * user_access_save, as the address that ptr points to is only used to
 	 * check if a watchpoint exists; ptr is never dereferenced.
 	 */
-	watchpoint = find_watchpoint((unsigned long)ptr, size, !is_write,
+	watchpoint = find_watchpoint((unsigned long)ptr, size,
+				     !(type & KCSAN_ACCESS_WRITE),
 				     &encoded_watchpoint);
 	/*
 	 * It is safe to check kcsan_is_enabled() after find_watchpoint in the
@@ -627,9 +745,42 @@ check_access(const volatile void *ptr, size_t size, int type, unsigned long ip)
 	else {
 		struct kcsan_ctx *ctx = get_ctx(); /* Call only once in fast-path. */
 
-		if (unlikely(should_watch(ctx, ptr, size, type)))
+		if (unlikely(should_watch(ctx, ptr, size, type))) {
 			kcsan_setup_watchpoint(ptr, size, type, ip);
-		else if (unlikely(ctx->scoped_accesses.prev))
+			return;
+		}
+
+		if (!(type & KCSAN_ACCESS_SCOPED)) {
+			struct kcsan_scoped_access *reorder_access = get_reorder_access(ctx);
+
+			if (reorder_access) {
+				/*
+				 * reorder_access check: simulates reordering of
+				 * the access after subsequent operations.
+				 */
+				ptr = reorder_access->ptr;
+				type = reorder_access->type;
+				ip = reorder_access->ip;
+				/*
+				 * Upon a nested interrupt, this context's
+				 * reorder_access can be modified (shared ctx).
+				 * We know that upon return, reorder_access is
+				 * always invalidated by setting size to 0 via
+				 * __tsan_func_exit(). Therefore we must read
+				 * and check size after the other fields.
+				 */
+				barrier();
+				size = READ_ONCE(reorder_access->size);
+				if (size)
+					goto again;
+			}
+		}
+
+		/*
+		 * Always checked last, right before returning from runtime;
+		 * if reorder_access is valid, checked after it was checked.
+		 */
+		if (unlikely(ctx->scoped_accesses.prev))
 			kcsan_check_scoped_accesses();
 	}
 }
@@ -916,19 +1067,60 @@ DEFINE_TSAN_VOLATILE_READ_WRITE(8);
 DEFINE_TSAN_VOLATILE_READ_WRITE(16);
 
 /*
- * The below are not required by KCSAN, but can still be emitted by the
- * compiler.
+ * Function entry and exit are used to determine the validty of reorder_access.
+ * Reordering of the access ends at the end of the function scope where the
+ * access happened. This is done for two reasons:
+ *
+ *	1. Artificially limits the scope where missing barriers are detected.
+ *	   This minimizes false positives due to uninstrumented functions that
+ *	   contain the required barriers but were missed.
+ *
+ *	2. Simplifies generating the stack trace of the access.
  */
 void __tsan_func_entry(void *call_pc);
-void __tsan_func_entry(void *call_pc)
+kcsan_noinstr void __tsan_func_entry(void *call_pc)
 {
+	if (!IS_ENABLED(CONFIG_KCSAN_WEAK_MEMORY) || within_noinstr(_RET_IP_))
+		return;
+
+	instrumentation_begin();
+	add_kcsan_stack_depth(1);
+	instrumentation_end();
 }
 EXPORT_SYMBOL(__tsan_func_entry);
+
 void __tsan_func_exit(void);
-void __tsan_func_exit(void)
+kcsan_noinstr void __tsan_func_exit(void)
 {
+	struct kcsan_scoped_access *reorder_access;
+
+	if (!IS_ENABLED(CONFIG_KCSAN_WEAK_MEMORY) || within_noinstr(_RET_IP_))
+		return;
+
+	instrumentation_begin();
+	reorder_access = get_reorder_access(get_ctx());
+	if (!reorder_access)
+		goto out;
+
+	if (get_kcsan_stack_depth() <= reorder_access->stack_depth) {
+		/*
+		 * Access check to catch cases where write without a barrier
+		 * (supposed release) was last access in function: because
+		 * instrumentation is inserted before the real access, a data
+		 * race due to the write giving up a c-s would only be caught if
+		 * we do the conflicting access after.
+		 */
+		check_access(reorder_access->ptr, reorder_access->size,
+			     reorder_access->type, reorder_access->ip);
+		reorder_access->size = 0;
+		reorder_access->stack_depth = INT_MIN;
+	}
+out:
+	add_kcsan_stack_depth(-1);
+	instrumentation_end();
 }
 EXPORT_SYMBOL(__tsan_func_exit);
+
 void __tsan_init(void);
 void __tsan_init(void)
 {
diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
index e0a93ffdef30..55b33bc11824 100644
--- a/lib/Kconfig.kcsan
+++ b/lib/Kconfig.kcsan
@@ -191,6 +191,22 @@ config KCSAN_STRICT
 	  closely aligns with the rules defined by the Linux-kernel memory
 	  consistency model (LKMM).
 
+config KCSAN_WEAK_MEMORY
+	bool "Enable weak memory modeling to detect missing memory barriers"
+	default y
+	depends on KCSAN_STRICT
+	help
+	  Enable support for modeling a subset of weak memory, which allows
+	  detecting a subset of data races due to missing memory barriers.
+
+	  Depends on KCSAN_STRICT, because the options strenghtening certain
+	  plain accesses by default (depending on !KCSAN_STRICT) reduce the
+	  ability to detect any data races invoving reordered accesses, in
+	  particular reordered writes.
+
+	  Weak memory modeling relies on additional instrumentation and may
+	  affect performance.
+
 config KCSAN_REPORT_VALUE_CHANGE_ONLY
 	bool "Only report races where watcher observed a data value change"
 	default y
diff --git a/scripts/Makefile.kcsan b/scripts/Makefile.kcsan
index 37cb504c77e1..4c7f0d282e42 100644
--- a/scripts/Makefile.kcsan
+++ b/scripts/Makefile.kcsan
@@ -9,7 +9,12 @@ endif
 
 # Keep most options here optional, to allow enabling more compilers if absence
 # of some options does not break KCSAN nor causes false positive reports.
-export CFLAGS_KCSAN := -fsanitize=thread \
-	$(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit=0) -fno-optimize-sibling-calls) \
+kcsan-cflags := -fsanitize=thread -fno-optimize-sibling-calls \
 	$(call cc-option,$(call cc-param,tsan-compound-read-before-write=1),$(call cc-option,$(call cc-param,tsan-instrument-read-before-write=1))) \
 	$(call cc-param,tsan-distinguish-volatile=1)
+
+ifndef CONFIG_KCSAN_WEAK_MEMORY
+kcsan-cflags += $(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit=0))
+endif
+
+export CFLAGS_KCSAN := $(kcsan-cflags)
