3 files changed, 19 insertions, 0 deletions
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index f69baba9e73..9d150b69f6a 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -297,6 +297,7 @@
 #![feature(maybe_uninit_slice)]
 #![feature(maybe_uninit_uninit_array)]
 #![feature(min_specialization)]
+#![cfg_attr(not(bootstrap), feature(must_not_suspend))]
 #![feature(needs_panic_runtime)]
 #![feature(negative_impls)]
 #![feature(never_type)]
diff --git a/library/std/src/sync/mutex.rs b/library/std/src/sync/mutex.rs
index e1d6324c17e..9abd4b547c7 100644
--- a/library/std/src/sync/mutex.rs
+++ b/library/std/src/sync/mutex.rs
@@ -188,6 +188,12 @@ unsafe impl<T: ?Sized + Send> Sync for Mutex<T> {}
 /// [`lock`]: Mutex::lock
 /// [`try_lock`]: Mutex::try_lock
 #[must_use = "if unused the Mutex will immediately unlock"]
+#[cfg_attr(
+    not(bootstrap),
+    must_not_suspend = "Holding a MutexGuard across suspend \
+                      points can cause deadlocks, delays, \
+                      and cause Future's to not implement `Send`"
+)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct MutexGuard<'a, T: ?Sized + 'a> {
     lock: &'a Mutex<T>,
diff --git a/library/std/src/sync/rwlock.rs b/library/std/src/sync/rwlock.rs
index e50d62d8173..1523d36323f 100644
--- a/library/std/src/sync/rwlock.rs
+++ b/library/std/src/sync/rwlock.rs
@@ -95,6 +95,12 @@ unsafe impl<T: ?Sized + Send + Sync> Sync for RwLock<T> {}
 /// [`read`]: RwLock::read
 /// [`try_read`]: RwLock::try_read
 #[must_use = "if unused the RwLock will immediately unlock"]
+#[cfg_attr(
+    not(bootstrap),
+    must_not_suspend = "Holding a RwLockReadGuard across suspend \
+                      points can cause deadlocks, delays, \
+                      and cause Future's to not implement `Send`"
+)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct RwLockReadGuard<'a, T: ?Sized + 'a> {
     lock: &'a RwLock<T>,
@@ -115,6 +121,12 @@ unsafe impl<T: ?Sized + Sync> Sync for RwLockReadGuard<'_, T> {}
 /// [`write`]: RwLock::write
 /// [`try_write`]: RwLock::try_write
 #[must_use = "if unused the RwLock will immediately unlock"]
+#[cfg_attr(
+    not(bootstrap),
+    must_not_suspend = "Holding a RwLockWriteGuard across suspend \
+                      points can cause deadlocks, delays, \
+                      and cause Future's to not implement `Send`"
+)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct RwLockWriteGuard<'a, T: ?Sized + 'a> {
     lock: &'a RwLock<T>,