diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
index 18e7eae9b5ba1740bbba91811bede4fff04e291b..0540f0156f58c7ae170f47867e9b88fb59592459 100644
--- a/include/linux/mmap_lock.h
+++ b/include/linux/mmap_lock.h
@@ -1,11 +1,65 @@
 #ifndef _LINUX_MMAP_LOCK_H
 #define _LINUX_MMAP_LOCK_H
 
+#include <linux/lockdep.h>
+#include <linux/mm_types.h>
 #include <linux/mmdebug.h>
+#include <linux/rwsem.h>
+#include <linux/tracepoint-defs.h>
+#include <linux/types.h>
 
 #define MMAP_LOCK_INITIALIZER(name) \
 	.mmap_lock = __RWSEM_INITIALIZER((name).mmap_lock),
 
+DECLARE_TRACEPOINT(mmap_lock_start_locking);
+DECLARE_TRACEPOINT(mmap_lock_acquire_returned);
+DECLARE_TRACEPOINT(mmap_lock_released);
+
+#ifdef CONFIG_TRACING
+
+void __mmap_lock_do_trace_start_locking(struct mm_struct *mm, bool write);
+void __mmap_lock_do_trace_acquire_returned(struct mm_struct *mm, bool write,
+					   bool success);
+void __mmap_lock_do_trace_released(struct mm_struct *mm, bool write);
+
+static inline void __mmap_lock_trace_start_locking(struct mm_struct *mm,
+						   bool write)
+{
+	if (tracepoint_enabled(mmap_lock_start_locking))
+		__mmap_lock_do_trace_start_locking(mm, write);
+}
+
+static inline void __mmap_lock_trace_acquire_returned(struct mm_struct *mm,
+						      bool write, bool success)
+{
+	if (tracepoint_enabled(mmap_lock_acquire_returned))
+		__mmap_lock_do_trace_acquire_returned(mm, write, success);
+}
+
+static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
+{
+	if (tracepoint_enabled(mmap_lock_released))
+		__mmap_lock_do_trace_released(mm, write);
+}
+
+#else /* !CONFIG_TRACING */
+
+static inline void __mmap_lock_trace_start_locking(struct mm_struct *mm,
+						   bool write)
+{
+}
+
+static inline void __mmap_lock_trace_acquire_returned(struct mm_struct *mm,
+						      bool write, bool success)
+{
+}
+
+static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
+{
+}
+
+#endif /* CONFIG_TRACING */
+
 static inline void mmap_init_lock(struct mm_struct *mm)
 {
 	init_rwsem(&mm->mmap_lock);
@@ -13,57 +67,86 @@ static inline void mmap_init_lock(struct mm_struct *mm)
 
 static inline void mmap_write_lock(struct mm_struct *mm)
 {
+	__mmap_lock_trace_start_locking(mm, true);
 	down_write(&mm->mmap_lock);
+	__mmap_lock_trace_acquire_returned(mm, true, true);
 }
 
 static inline void mmap_write_lock_nested(struct mm_struct *mm, int subclass)
 {
+	__mmap_lock_trace_start_locking(mm, true);
 	down_write_nested(&mm->mmap_lock, subclass);
+	__mmap_lock_trace_acquire_returned(mm, true, true);
 }
 
 static inline int mmap_write_lock_killable(struct mm_struct *mm)
 {
-	return down_write_killable(&mm->mmap_lock);
+	int ret;
+
+	__mmap_lock_trace_start_locking(mm, true);
+	ret = down_write_killable(&mm->mmap_lock);
+	__mmap_lock_trace_acquire_returned(mm, true, ret == 0);
+	return ret;
 }
 
 static inline bool mmap_write_trylock(struct mm_struct *mm)
 {
-	return down_write_trylock(&mm->mmap_lock) != 0;
+	bool ret;
+
+	__mmap_lock_trace_start_locking(mm, true);
+	ret = down_write_trylock(&mm->mmap_lock) != 0;
+	__mmap_lock_trace_acquire_returned(mm, true, ret);
+	return ret;
 }
 
 static inline void mmap_write_unlock(struct mm_struct *mm)
 {
 	up_write(&mm->mmap_lock);
+	__mmap_lock_trace_released(mm, true);
 }
 
 static inline void mmap_write_downgrade(struct mm_struct *mm)
 {
 	downgrade_write(&mm->mmap_lock);
+	__mmap_lock_trace_acquire_returned(mm, false, true);
 }
 
 static inline void mmap_read_lock(struct mm_struct *mm)
 {
+	__mmap_lock_trace_start_locking(mm, false);
 	down_read(&mm->mmap_lock);
+	__mmap_lock_trace_acquire_returned(mm, false, true);
 }
 
 static inline int mmap_read_lock_killable(struct mm_struct *mm)
 {
-	return down_read_killable(&mm->mmap_lock);
+	int ret;
+
+	__mmap_lock_trace_start_locking(mm, false);
+	ret = down_read_killable(&mm->mmap_lock);
+	__mmap_lock_trace_acquire_returned(mm, false, ret == 0);
+	return ret;
 }
 
 static inline bool mmap_read_trylock(struct mm_struct *mm)
 {
-	return down_read_trylock(&mm->mmap_lock) != 0;
+	bool ret;
+
+	__mmap_lock_trace_start_locking(mm, false);
+	ret = down_read_trylock(&mm->mmap_lock) != 0;
+	__mmap_lock_trace_acquire_returned(mm, false, ret);
+	return ret;
 }
 
 static inline void mmap_read_unlock(struct mm_struct *mm)
 {
 	up_read(&mm->mmap_lock);
+	__mmap_lock_trace_released(mm, false);
 }
 
 static inline bool mmap_read_trylock_non_owner(struct mm_struct *mm)
 {
-	if (down_read_trylock(&mm->mmap_lock)) {
+	if (mmap_read_trylock(mm)) {
 		rwsem_release(&mm->mmap_lock.dep_map, _RET_IP_);
 		return true;
 	}
@@ -73,6 +156,7 @@ static inline bool mmap_read_trylock_non_owner(struct mm_struct *mm)
 static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)
 {
 	up_read_non_owner(&mm->mmap_lock);
+	__mmap_lock_trace_released(mm, false);
 }
 
 static inline void mmap_assert_locked(struct mm_struct *mm)
diff --git a/include/trace/events/mmap_lock.h b/include/trace/events/mmap_lock.h
new file mode 100644
index 0000000000000000000000000000000000000000..0abff67b96f09a84e89e29d360103ce328d5ac96
--- /dev/null
+++ b/include/trace/events/mmap_lock.h
@@ -0,0 +1,107 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM mmap_lock
+
+#if !defined(_TRACE_MMAP_LOCK_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_MMAP_LOCK_H
+
+#include <linux/tracepoint.h>
+#include <linux/types.h>
+
+struct mm_struct;
+
+extern int trace_mmap_lock_reg(void);
+extern void trace_mmap_lock_unreg(void);
+
+TRACE_EVENT_FN(mmap_lock_start_locking,
+
+	TP_PROTO(struct mm_struct *mm, const char *memcg_path, bool write),
+
+	TP_ARGS(mm, memcg_path, write),
+
+	TP_STRUCT__entry(
+		__field(struct mm_struct *, mm)
+		__string(memcg_path, memcg_path)
+		__field(bool, write)
+	),
+
+	TP_fast_assign(
+		__entry->mm = mm;
+		__assign_str(memcg_path, memcg_path);
+		__entry->write = write;
+	),
+
+	TP_printk(
+		"mm=%p memcg_path=%s write=%s\n",
+		__entry->mm,
+		__get_str(memcg_path),
+		__entry->write ? "true" : "false"
+	),
+
+	trace_mmap_lock_reg, trace_mmap_lock_unreg
+);
+
+TRACE_EVENT_FN(mmap_lock_acquire_returned,
+
+	TP_PROTO(struct mm_struct *mm, const char *memcg_path, bool write,
+		bool success),
+
+	TP_ARGS(mm, memcg_path, write, success),
+
+	TP_STRUCT__entry(
+		__field(struct mm_struct *, mm)
+		__string(memcg_path, memcg_path)
+		__field(bool, write)
+		__field(bool, success)
+	),
+
+	TP_fast_assign(
+		__entry->mm = mm;
+		__assign_str(memcg_path, memcg_path);
+		__entry->write = write;
+		__entry->success = success;
+	),
+
+	TP_printk(
+		"mm=%p memcg_path=%s write=%s success=%s\n",
+		__entry->mm,
+		__get_str(memcg_path),
+		__entry->write ? "true" : "false",
+		__entry->success ? "true" : "false"
+	),
+
+	trace_mmap_lock_reg, trace_mmap_lock_unreg
+);
+
+TRACE_EVENT_FN(mmap_lock_released,
+
+	TP_PROTO(struct mm_struct *mm, const char *memcg_path, bool write),
+
+	TP_ARGS(mm, memcg_path, write),
+
+	TP_STRUCT__entry(
+		__field(struct mm_struct *, mm)
+		__string(memcg_path, memcg_path)
+		__field(bool, write)
+	),
+
+	TP_fast_assign(
+		__entry->mm = mm;
+		__assign_str(memcg_path, memcg_path);
+		__entry->write = write;
+	),
+
+	TP_printk(
+		"mm=%p memcg_path=%s write=%s\n",
+		__entry->mm,
+		__get_str(memcg_path),
+		__entry->write ? "true" : "false"
+	),
+
+	trace_mmap_lock_reg, trace_mmap_lock_unreg
+);
+
+#endif /* _TRACE_MMAP_LOCK_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/mm/Makefile b/mm/Makefile
index 069f216e109ea66a4a012a47107b3d5554f9659f..b6cd2fffa4922f984060ef3d38930cc1ccc73674 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -52,7 +52,7 @@ obj-y			:= filemap.o mempool.o oom_kill.o fadvise.o \
 			   mm_init.o percpu.o slab_common.o \
 			   compaction.o vmacache.o \
 			   interval_tree.o list_lru.o workingset.o \
-			   debug.o gup.o $(mmu-y)
+			   debug.o gup.o mmap_lock.o $(mmu-y)
 
 # Give 'page_alloc' its own module-parameter namespace
 page-alloc-y := page_alloc.o
diff --git a/mm/mmap_lock.c b/mm/mmap_lock.c
new file mode 100644
index 0000000000000000000000000000000000000000..dcdde4f722a408ff05fa0d5e86ba1465a60ce0ea
--- /dev/null
+++ b/mm/mmap_lock.c
@@ -0,0 +1,230 @@
+// SPDX-License-Identifier: GPL-2.0
+#define CREATE_TRACE_POINTS
+#include <trace/events/mmap_lock.h>
+
+#include <linux/mm.h>
+#include <linux/cgroup.h>
+#include <linux/memcontrol.h>
+#include <linux/mmap_lock.h>
+#include <linux/mutex.h>
+#include <linux/percpu.h>
+#include <linux/rcupdate.h>
+#include <linux/smp.h>
+#include <linux/trace_events.h>
+
+EXPORT_TRACEPOINT_SYMBOL(mmap_lock_start_locking);
+EXPORT_TRACEPOINT_SYMBOL(mmap_lock_acquire_returned);
+EXPORT_TRACEPOINT_SYMBOL(mmap_lock_released);
+
+#ifdef CONFIG_MEMCG
+
+/*
+ * Our various events all share the same buffer (because we don't want or need
+ * to allocate a set of buffers *per event type*), so we need to protect against
+ * concurrent _reg() and _unreg() calls, and count how many _reg() calls have
+ * been made.
+ */
+static DEFINE_MUTEX(reg_lock);
+static int reg_refcount; /* Protected by reg_lock. */
+
+/*
+ * Size of the buffer for memcg path names. Ignoring stack trace support,
+ * trace_events_hist.c uses MAX_FILTER_STR_VAL for this, so we also use it.
+ */
+#define MEMCG_PATH_BUF_SIZE MAX_FILTER_STR_VAL
+
+/*
+ * How many contexts our trace events might be called in: normal, softirq, irq,
+ * and NMI.
+ */
+#define CONTEXT_COUNT 4
+
+static DEFINE_PER_CPU(char __rcu *, memcg_path_buf);
+static char **tmp_bufs;
+static DEFINE_PER_CPU(int, memcg_path_buf_idx);
+
+/* Called with reg_lock held. */
+static void free_memcg_path_bufs(void)
+{
+	int cpu;
+	char **old = tmp_bufs;
+
+	for_each_possible_cpu(cpu) {
+		*(old++) = rcu_dereference_protected(
+			per_cpu(memcg_path_buf, cpu),
+			lockdep_is_held(&reg_lock));
+		rcu_assign_pointer(per_cpu(memcg_path_buf, cpu), NULL);
+	}
+
+	/* Wait for inflight memcg_path_buf users to finish. */
+	synchronize_rcu();
+
+	old = tmp_bufs;
+	for_each_possible_cpu(cpu) {
+		kfree(*(old++));
+	}
+
+	kfree(tmp_bufs);
+	tmp_bufs = NULL;
+}
+
+int trace_mmap_lock_reg(void)
+{
+	int cpu;
+	char *new;
+
+	mutex_lock(&reg_lock);
+
+	/* If the refcount is going 0->1, proceed with allocating buffers. */
+	if (reg_refcount++)
+		goto out;
+
+	tmp_bufs = kmalloc_array(num_possible_cpus(), sizeof(*tmp_bufs),
+				 GFP_KERNEL);
+	if (tmp_bufs == NULL)
+		goto out_fail;
+
+	for_each_possible_cpu(cpu) {
+		new = kmalloc(MEMCG_PATH_BUF_SIZE * CONTEXT_COUNT, GFP_KERNEL);
+		if (new == NULL)
+			goto out_fail_free;
+		rcu_assign_pointer(per_cpu(memcg_path_buf, cpu), new);
+		/* Don't need to wait for inflights, they'd have gotten NULL. */
+	}
+
+out:
+	mutex_unlock(&reg_lock);
+	return 0;
+
+out_fail_free:
+	free_memcg_path_bufs();
+out_fail:
+	/* Since we failed, undo the earlier ref increment. */
+	--reg_refcount;
+
+	mutex_unlock(&reg_lock);
+	return -ENOMEM;
+}
+
+void trace_mmap_lock_unreg(void)
+{
+	mutex_lock(&reg_lock);
+
+	/* If the refcount is going 1->0, proceed with freeing buffers. */
+	if (--reg_refcount)
+		goto out;
+
+	free_memcg_path_bufs();
+
+out:
+	mutex_unlock(&reg_lock);
+}
+
+static inline char *get_memcg_path_buf(void)
+{
+	char *buf;
+	int idx;
+
+	rcu_read_lock();
+	buf = rcu_dereference(*this_cpu_ptr(&memcg_path_buf));
+	if (buf == NULL) {
+		rcu_read_unlock();
+		return NULL;
+	}
+	idx = this_cpu_add_return(memcg_path_buf_idx, MEMCG_PATH_BUF_SIZE) -
+	      MEMCG_PATH_BUF_SIZE;
+	return &buf[idx];
+}
+
+static inline void put_memcg_path_buf(void)
+{
+	this_cpu_sub(memcg_path_buf_idx, MEMCG_PATH_BUF_SIZE);
+	rcu_read_unlock();
+}
+
+/*
+ * Write the given mm_struct's memcg path to a percpu buffer, and return a
+ * pointer to it. If the path cannot be determined, or no buffer was available
+ * (because the trace event is being unregistered), NULL is returned.
+ *
+ * Note: buffers are allocated per-cpu to avoid locking, so preemption must be
+ * disabled by the caller before calling us, and re-enabled only after the
+ * caller is done with the pointer.
+ *
+ * The caller must call put_memcg_path_buf() once the buffer is no longer
+ * needed. This must be done while preemption is still disabled.
+ */
+static const char *get_mm_memcg_path(struct mm_struct *mm)
+{
+	char *buf = NULL;
+	struct mem_cgroup *memcg = get_mem_cgroup_from_mm(mm);
+
+	if (memcg == NULL)
+		goto out;
+	if (unlikely(memcg->css.cgroup == NULL))
+		goto out_put;
+
+	buf = get_memcg_path_buf();
+	if (buf == NULL)
+		goto out_put;
+
+	cgroup_path(memcg->css.cgroup, buf, MEMCG_PATH_BUF_SIZE);
+
+out_put:
+	css_put(&memcg->css);
+out:
+	return buf;
+}
+
+#define TRACE_MMAP_LOCK_EVENT(type, mm, ...)                                   \
+	do {                                                                   \
+		const char *memcg_path;                                        \
+		preempt_disable();                                             \
+		memcg_path = get_mm_memcg_path(mm);                            \
+		trace_mmap_lock_##type(mm,                                     \
+				       memcg_path != NULL ? memcg_path : "",   \
+				       ##__VA_ARGS__);                         \
+		if (likely(memcg_path != NULL))                                \
+			put_memcg_path_buf();                                  \
+		preempt_enable();                                              \
+	} while (0)
+
+#else /* !CONFIG_MEMCG */
+
+int trace_mmap_lock_reg(void)
+{
+	return 0;
+}
+
+void trace_mmap_lock_unreg(void)
+{
+}
+
+#define TRACE_MMAP_LOCK_EVENT(type, mm, ...)                                   \
+	trace_mmap_lock_##type(mm, "", ##__VA_ARGS__)
+
+#endif /* CONFIG_MEMCG */
+
+/*
+ * Trace calls must be in a separate file, as otherwise there's a circular
+ * dependency between linux/mmap_lock.h and trace/events/mmap_lock.h.
+ */
+
+void __mmap_lock_do_trace_start_locking(struct mm_struct *mm, bool write)
+{
+	TRACE_MMAP_LOCK_EVENT(start_locking, mm, write);
+}
+EXPORT_SYMBOL(__mmap_lock_do_trace_start_locking);
+
+void __mmap_lock_do_trace_acquire_returned(struct mm_struct *mm, bool write,
+					   bool success)
+{
+	TRACE_MMAP_LOCK_EVENT(acquire_returned, mm, write, success);
+}
+EXPORT_SYMBOL(__mmap_lock_do_trace_acquire_returned);
+
+void __mmap_lock_do_trace_released(struct mm_struct *mm, bool write)
+{
+	TRACE_MMAP_LOCK_EVENT(released, mm, write);
+}
+EXPORT_SYMBOL(__mmap_lock_do_trace_released);