Auto merge of #3145 - RalfJung:data-race-error, r=RalfJung

give some more help for the unusual data races Fixes https://github.com/rust-lang/miri/issues/3142
2024-11-22 23:04:33 +00:00 · 2023-11-04 13:59:54 +00:00 · 2023-11-04 13:59:54 +00:00 · 2ef639d4fb
commit 2ef639d4fb
parent 1b2e4a9c94 278965a0c4
73 changed files with 233 additions and 166 deletions
--- a/src/tools/miri/src/concurrency/data_race.rs
+++ b/src/tools/miri/src/concurrency/data_race.rs
@ -41,7 +41,6 @@
 //! on the data-race detection code.

 use std::{
-    borrow::Cow,
    cell::{Cell, Ref, RefCell, RefMut},
    fmt::Debug,
    mem,
@ -206,7 +205,7 @@ enum AtomicAccessType {
 /// are all treated as writes for the purpose
 /// of the data-race detector.
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
-enum WriteType {
+enum NaWriteType {
    /// Allocate memory.
    Allocate,

@ -219,12 +218,48 @@ enum WriteType {
    /// (Same for `Allocate` above.)
    Deallocate,
 }
-impl WriteType {
-    fn get_descriptor(self) -> &'static str {
+
+impl NaWriteType {
+    fn description(self) -> &'static str {
        match self {
-            WriteType::Allocate => "Allocate",
-            WriteType::Write => "Write",
-            WriteType::Deallocate => "Deallocate",
+            NaWriteType::Allocate => "creating a new allocation",
+            NaWriteType::Write => "non-atomic write",
+            NaWriteType::Deallocate => "deallocation",
+        }
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+enum AccessType {
+    NaRead,
+    NaWrite(NaWriteType),
+    AtomicLoad,
+    AtomicStore,
+    AtomicRmw,
+}
+
+impl AccessType {
+    fn description(self) -> &'static str {
+        match self {
+            AccessType::NaRead => "non-atomic read",
+            AccessType::NaWrite(w) => w.description(),
+            AccessType::AtomicLoad => "atomic load",
+            AccessType::AtomicStore => "atomic store",
+            AccessType::AtomicRmw => "atomic read-modify-write",
+        }
+    }
+
+    fn is_atomic(self) -> bool {
+        match self {
+            AccessType::AtomicLoad | AccessType::AtomicStore | AccessType::AtomicRmw => true,
+            AccessType::NaRead | AccessType::NaWrite(_) => false,
+        }
+    }
+
+    fn is_read(self) -> bool {
+        match self {
+            AccessType::AtomicLoad | AccessType::NaRead => true,
+            AccessType::NaWrite(_) | AccessType::AtomicStore | AccessType::AtomicRmw => false,
        }
    }
 }
@ -241,7 +276,7 @@ struct MemoryCellClocks {
    /// The type of operation that the write index represents,
    /// either newly allocated memory, a non-atomic write or
    /// a deallocation of memory.
-    write_type: WriteType,
+    write_type: NaWriteType,

    /// The vector-clock of all non-atomic reads that happened since the last non-atomic write
    /// (i.e., we join together the "singleton" clocks corresponding to each read). It is reset to
@ -272,7 +307,7 @@ impl MemoryCellClocks {
        MemoryCellClocks {
            read: VClock::default(),
            write: (alloc_index, alloc),
-            write_type: WriteType::Allocate,
+            write_type: NaWriteType::Allocate,
            atomic_ops: None,
        }
    }
@ -495,7 +530,7 @@ impl MemoryCellClocks {
        &mut self,
        thread_clocks: &mut ThreadClockSet,
        index: VectorIdx,
-        write_type: WriteType,
+        write_type: NaWriteType,
        current_span: Span,
    ) -> Result<(), DataRace> {
        log::trace!("Unsynchronized write with vectors: {:#?} :: {:#?}", self, thread_clocks);
@ -845,48 +880,45 @@ impl VClockAlloc {
        global: &GlobalState,
        thread_mgr: &ThreadManager<'_, '_>,
        mem_clocks: &MemoryCellClocks,
-        action: &str,
-        is_atomic: bool,
+        access: AccessType,
        access_size: Size,
        ptr_dbg: Pointer<AllocId>,
    ) -> InterpResult<'tcx> {
        let (current_index, current_clocks) = global.current_thread_state(thread_mgr);
-        let mut action = Cow::Borrowed(action);
-        let mut involves_non_atomic = true;
+        let mut other_size = None; // if `Some`, this was a size-mismatch race
        let write_clock;
-        let (other_action, other_thread, other_clock) =
+        let (other_access, other_thread, other_clock) =
            // First check the atomic-nonatomic cases. If it looks like multiple
            // cases apply, this one should take precedence, else it might look like
            // we are reporting races between two non-atomic reads.
-            if !is_atomic &&
+            if !access.is_atomic() &&
                let Some(atomic) = mem_clocks.atomic() &&
                let Some(idx) = Self::find_gt_index(&atomic.write_vector, &current_clocks.clock)
            {
-                (format!("Atomic Store"), idx, &atomic.write_vector)
-            } else if !is_atomic &&
+                (AccessType::AtomicStore, idx, &atomic.write_vector)
+            } else if !access.is_atomic() &&
                let Some(atomic) = mem_clocks.atomic() &&
                let Some(idx) = Self::find_gt_index(&atomic.read_vector, &current_clocks.clock)
            {
-                (format!("Atomic Load"), idx, &atomic.read_vector)
+                (AccessType::AtomicLoad, idx, &atomic.read_vector)
            // Then check races with non-atomic writes/reads.
            } else if mem_clocks.write.1 > current_clocks.clock[mem_clocks.write.0] {
                write_clock = mem_clocks.write();
-                (mem_clocks.write_type.get_descriptor().to_owned(), mem_clocks.write.0, &write_clock)
+                (AccessType::NaWrite(mem_clocks.write_type), mem_clocks.write.0, &write_clock)
            } else if let Some(idx) = Self::find_gt_index(&mem_clocks.read, &current_clocks.clock) {
-                (format!("Read"), idx, &mem_clocks.read)
+                (AccessType::NaRead, idx, &mem_clocks.read)
            // Finally, mixed-size races.
-            } else if is_atomic && let Some(atomic) = mem_clocks.atomic() && atomic.size != access_size {
+            } else if access.is_atomic() && let Some(atomic) = mem_clocks.atomic() && atomic.size != access_size {
                // This is only a race if we are not synchronized with all atomic accesses, so find
                // the one we are not synchronized with.
-                involves_non_atomic = false;
-                action = format!("{}-byte (different-size) {action}", access_size.bytes()).into();
+                other_size = Some(atomic.size);
                if let Some(idx) = Self::find_gt_index(&atomic.write_vector, &current_clocks.clock)
                    {
-                        (format!("{}-byte Atomic Store", atomic.size.bytes()), idx, &atomic.write_vector)
+                        (AccessType::AtomicStore, idx, &atomic.write_vector)
                    } else if let Some(idx) =
                        Self::find_gt_index(&atomic.read_vector, &current_clocks.clock)
                    {
-                        (format!("{}-byte Atomic Load", atomic.size.bytes()), idx, &atomic.read_vector)
+                        (AccessType::AtomicLoad, idx, &atomic.read_vector)
                    } else {
                        unreachable!(
                            "Failed to report data-race for mixed-size access: no race found"
@ -899,18 +931,39 @@ impl VClockAlloc {
        // Load elaborated thread information about the racing thread actions.
        let current_thread_info = global.print_thread_metadata(thread_mgr, current_index);
        let other_thread_info = global.print_thread_metadata(thread_mgr, other_thread);
+        let involves_non_atomic = !access.is_atomic() || !other_access.is_atomic();

        // Throw the data-race detection.
+        let extra = if other_size.is_some() {
+            assert!(!involves_non_atomic);
+            Some("overlapping unsynchronized atomic accesses must use the same access size")
+        } else if access.is_read() && other_access.is_read() {
+            assert!(involves_non_atomic);
+            Some(
+                "overlapping atomic and non-atomic accesses must be synchronized, even if both are read-only",
+            )
+        } else {
+            None
+        };
        Err(err_machine_stop!(TerminationInfo::DataRace {
            involves_non_atomic,
+            extra,
            ptr: ptr_dbg,
            op1: RacingOp {
-                action: other_action.to_string(),
+                action: if let Some(other_size) = other_size {
+                    format!("{}-byte {}", other_size.bytes(), other_access.description())
+                } else {
+                    other_access.description().to_owned()
+                },
                thread_info: other_thread_info,
                span: other_clock.as_slice()[other_thread.index()].span_data(),
            },
            op2: RacingOp {
-                action: action.to_string(),
+                action: if other_size.is_some() {
+                    format!("{}-byte {}", access_size.bytes(), access.description())
+                } else {
+                    access.description().to_owned()
+                },
                thread_info: current_thread_info,
                span: current_clocks.clock.as_slice()[current_index.index()].span_data(),
            },
@ -945,8 +998,7 @@ impl VClockAlloc {
                        global,
                        &machine.threads,
                        mem_clocks,
-                        "Read",
-                        /* is_atomic */ false,
+                        AccessType::NaRead,
                        access_range.size,
                        Pointer::new(alloc_id, Size::from_bytes(mem_clocks_range.start)),
                    );
@ -963,7 +1015,7 @@ impl VClockAlloc {
        &mut self,
        alloc_id: AllocId,
        access_range: AllocRange,
-        write_type: WriteType,
+        write_type: NaWriteType,
        machine: &mut MiriMachine<'_, '_>,
    ) -> InterpResult<'tcx> {
        let current_span = machine.current_span();
@ -985,8 +1037,7 @@ impl VClockAlloc {
                        global,
                        &machine.threads,
                        mem_clocks,
-                        write_type.get_descriptor(),
-                        /* is_atomic */ false,
+                        AccessType::NaWrite(write_type),
                        access_range.size,
                        Pointer::new(alloc_id, Size::from_bytes(mem_clocks_range.start)),
                    );
@ -1008,7 +1059,7 @@ impl VClockAlloc {
        range: AllocRange,
        machine: &mut MiriMachine<'_, '_>,
    ) -> InterpResult<'tcx> {
-        self.unique_access(alloc_id, range, WriteType::Write, machine)
+        self.unique_access(alloc_id, range, NaWriteType::Write, machine)
    }

    /// Detect data-races for an unsynchronized deallocate operation, will not perform
@ -1021,7 +1072,7 @@ impl VClockAlloc {
        range: AllocRange,
        machine: &mut MiriMachine<'_, '_>,
    ) -> InterpResult<'tcx> {
-        self.unique_access(alloc_id, range, WriteType::Deallocate, machine)
+        self.unique_access(alloc_id, range, NaWriteType::Deallocate, machine)
    }
 }

@ -1134,7 +1185,7 @@ trait EvalContextPrivExt<'mir, 'tcx: 'mir>: MiriInterpCxExt<'mir, 'tcx> {
        this.validate_atomic_op(
            place,
            atomic,
-            "Atomic Load",
+            AccessType::AtomicLoad,
            move |memory, clocks, index, atomic| {
                if atomic == AtomicReadOrd::Relaxed {
                    memory.load_relaxed(&mut *clocks, index, place.layout.size)
@ -1156,7 +1207,7 @@ trait EvalContextPrivExt<'mir, 'tcx: 'mir>: MiriInterpCxExt<'mir, 'tcx> {
        this.validate_atomic_op(
            place,
            atomic,
-            "Atomic Store",
+            AccessType::AtomicStore,
            move |memory, clocks, index, atomic| {
                if atomic == AtomicWriteOrd::Relaxed {
                    memory.store_relaxed(clocks, index, place.layout.size)
@ -1178,18 +1229,23 @@ trait EvalContextPrivExt<'mir, 'tcx: 'mir>: MiriInterpCxExt<'mir, 'tcx> {
        let acquire = matches!(atomic, Acquire | AcqRel | SeqCst);
        let release = matches!(atomic, Release | AcqRel | SeqCst);
        let this = self.eval_context_mut();
-        this.validate_atomic_op(place, atomic, "Atomic RMW", move |memory, clocks, index, _| {
-            if acquire {
-                memory.load_acquire(clocks, index, place.layout.size)?;
-            } else {
-                memory.load_relaxed(clocks, index, place.layout.size)?;
-            }
-            if release {
-                memory.rmw_release(clocks, index, place.layout.size)
-            } else {
-                memory.rmw_relaxed(clocks, index, place.layout.size)
-            }
-        })
+        this.validate_atomic_op(
+            place,
+            atomic,
+            AccessType::AtomicRmw,
+            move |memory, clocks, index, _| {
+                if acquire {
+                    memory.load_acquire(clocks, index, place.layout.size)?;
+                } else {
+                    memory.load_relaxed(clocks, index, place.layout.size)?;
+                }
+                if release {
+                    memory.rmw_release(clocks, index, place.layout.size)
+                } else {
+                    memory.rmw_relaxed(clocks, index, place.layout.size)
+                }
+            },
+        )
    }

    /// Generic atomic operation implementation
@ -1197,7 +1253,7 @@ trait EvalContextPrivExt<'mir, 'tcx: 'mir>: MiriInterpCxExt<'mir, 'tcx> {
        &self,
        place: &MPlaceTy<'tcx, Provenance>,
        atomic: A,
-        description: &str,
+        access: AccessType,
        mut op: impl FnMut(
            &mut MemoryCellClocks,
            &mut ThreadClockSet,
@ -1206,6 +1262,7 @@ trait EvalContextPrivExt<'mir, 'tcx: 'mir>: MiriInterpCxExt<'mir, 'tcx> {
        ) -> Result<(), DataRace>,
    ) -> InterpResult<'tcx> {
        let this = self.eval_context_ref();
+        assert!(access.is_atomic());
        if let Some(data_race) = &this.machine.data_race {
            if data_race.race_detecting() {
                let size = place.layout.size;
@ -1215,7 +1272,7 @@ trait EvalContextPrivExt<'mir, 'tcx: 'mir>: MiriInterpCxExt<'mir, 'tcx> {
                let alloc_meta = this.get_alloc_extra(alloc_id)?.data_race.as_ref().unwrap();
                log::trace!(
                    "Atomic op({}) with ordering {:?} on {:?} (size={})",
-                    description,
+                    access.description(),
                    &atomic,
                    place.ptr(),
                    size.bytes()
@ -1237,8 +1294,7 @@ trait EvalContextPrivExt<'mir, 'tcx: 'mir>: MiriInterpCxExt<'mir, 'tcx> {
                                    data_race,
                                    &this.machine.threads,
                                    mem_clocks,
-                                    description,
-                                    /* is_atomic */ true,
+                                    access,
                                    place.layout.size,
                                    Pointer::new(
                                        alloc_id,
--- a/src/tools/miri/src/diagnostics.rs
+++ b/src/tools/miri/src/diagnostics.rs
@ -47,6 +47,7 @@ pub enum TerminationInfo {
        ptr: Pointer,
        op1: RacingOp,
        op2: RacingOp,
+        extra: Option<&'static str>,
    },
 }

@ -75,7 +76,7 @@ impl fmt::Display for TerminationInfo {
                write!(f, "multiple definitions of symbol `{link_name}`"),
            SymbolShimClashing { link_name, .. } =>
                write!(f, "found `{link_name}` symbol definition that clashes with a built-in shim",),
-            DataRace { involves_non_atomic, ptr, op1, op2 } =>
+            DataRace { involves_non_atomic, ptr, op1, op2, .. } =>
                write!(
                    f,
                    "{} detected between (1) {} on {} and (2) {} on {} at {ptr:?}. (2) just happened here",
@ -266,12 +267,16 @@ pub fn report_error<'tcx, 'mir>(
                vec![(Some(*span), format!("the `{link_name}` symbol is defined here"))],
            Int2PtrWithStrictProvenance =>
                vec![(None, format!("use Strict Provenance APIs (https://doc.rust-lang.org/nightly/std/ptr/index.html#strict-provenance, https://crates.io/crates/sptr) instead"))],
-            DataRace { op1, .. } =>
-                vec![
-                    (Some(op1.span), format!("and (1) occurred earlier here")),
-                    (None, format!("this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior")),
-                    (None, format!("see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information")),
-                ],
+            DataRace { op1, extra, .. } => {
+                let mut helps = vec![(Some(op1.span), format!("and (1) occurred earlier here"))];
+                if let Some(extra) = extra {
+                    helps.push((None, format!("{extra}")))
+                }
+                helps.push((None, format!("this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior")));
+                helps.push((None, format!("see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information")));
+                helps
+            }
+                ,
            _ => vec![],
        };
        (title, helps)
--- a/src/tools/miri/tests/fail/both_borrows/retag_data_race_write.rs
+++ b/src/tools/miri/tests/fail/both_borrows/retag_data_race_write.rs
@ -17,7 +17,7 @@ fn thread_1(p: SendPtr) {
 fn thread_2(p: SendPtr) {
    let p = p.0;
    unsafe {
-        *p = 5; //~ ERROR: /Data race detected between \(1\) (Read|Write) on thread `<unnamed>` and \(2\) Write on thread `<unnamed>`/
+        *p = 5; //~ ERROR: /Data race detected between \(1\) non-atomic (read|write) on thread `<unnamed>` and \(2\) non-atomic write on thread `<unnamed>`/
    }
 }

--- a/src/tools/miri/tests/fail/both_borrows/retag_data_race_write.stack.stderr
+++ b/src/tools/miri/tests/fail/both_borrows/retag_data_race_write.stack.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/retag_data_race_write.rs:LL:CC
   |
 LL |         *p = 5;
-   |         ^^^^^^ Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+   |         ^^^^^^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/retag_data_race_write.rs:LL:CC
--- a/src/tools/miri/tests/fail/both_borrows/retag_data_race_write.tree.stderr
+++ b/src/tools/miri/tests/fail/both_borrows/retag_data_race_write.tree.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Read on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/retag_data_race_write.rs:LL:CC
   |
 LL |         *p = 5;
-   |         ^^^^^^ Data race detected between (1) Read on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+   |         ^^^^^^ Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/retag_data_race_write.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/alloc_read_race.rs
+++ b/src/tools/miri/tests/fail/data_race/alloc_read_race.rs
@ -39,7 +39,7 @@ pub fn main() {
            let pointer = &*ptr.0;

            // Note: could also error due to reading uninitialized memory, but the data-race detector triggers first.
-            *pointer.load(Ordering::Relaxed) //~ ERROR: Data race detected between (1) Allocate on thread `<unnamed>` and (2) Read on thread `<unnamed>`
+            *pointer.load(Ordering::Relaxed) //~ ERROR: Data race detected between (1) creating a new allocation on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>`
        });

        j1.join().unwrap();
--- a/src/tools/miri/tests/fail/data_race/alloc_read_race.stderr
+++ b/src/tools/miri/tests/fail/data_race/alloc_read_race.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Allocate on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) creating a new allocation on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/alloc_read_race.rs:LL:CC
   |
 LL |             *pointer.load(Ordering::Relaxed)
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) Allocate on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) creating a new allocation on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/alloc_read_race.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/alloc_write_race.rs
+++ b/src/tools/miri/tests/fail/data_race/alloc_write_race.rs
@ -37,7 +37,7 @@ pub fn main() {
        let j2 = spawn(move || {
            let ptr = ptr; // avoid field capturing
            let pointer = &*ptr.0;
-            *pointer.load(Ordering::Relaxed) = 2; //~ ERROR: Data race detected between (1) Allocate on thread `<unnamed>` and (2) Write on thread `<unnamed>`
+            *pointer.load(Ordering::Relaxed) = 2; //~ ERROR: Data race detected between (1) creating a new allocation on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>`
        });

        j1.join().unwrap();
--- a/src/tools/miri/tests/fail/data_race/alloc_write_race.stderr
+++ b/src/tools/miri/tests/fail/data_race/alloc_write_race.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Allocate on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) creating a new allocation on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/alloc_write_race.rs:LL:CC
   |
 LL |             *pointer.load(Ordering::Relaxed) = 2;
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) Allocate on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) creating a new allocation on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/alloc_write_race.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/atomic_read_na_write_race1.rs
+++ b/src/tools/miri/tests/fail/data_race/atomic_read_na_write_race1.rs
@ -22,7 +22,7 @@ pub fn main() {

        let j2 = spawn(move || {
            let c = c; // avoid field capturing
-            (&*c.0).load(Ordering::SeqCst) //~ ERROR: Data race detected between (1) Write on thread `<unnamed>` and (2) Atomic Load on thread `<unnamed>`
+            (&*c.0).load(Ordering::SeqCst) //~ ERROR: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) atomic load on thread `<unnamed>`
        });

        j1.join().unwrap();
--- a/src/tools/miri/tests/fail/data_race/atomic_read_na_write_race1.stderr
+++ b/src/tools/miri/tests/fail/data_race/atomic_read_na_write_race1.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Atomic Load on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) atomic load on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/atomic_read_na_write_race1.rs:LL:CC
   |
 LL |             (&*c.0).load(Ordering::SeqCst)
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) Write on thread `<unnamed>` and (2) Atomic Load on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) atomic load on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/atomic_read_na_write_race1.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/atomic_read_na_write_race2.rs
+++ b/src/tools/miri/tests/fail/data_race/atomic_read_na_write_race2.rs
@ -25,7 +25,7 @@ pub fn main() {
        let j2 = spawn(move || {
            let c = c; // avoid field capturing
            let atomic_ref = &mut *c.0;
-            *atomic_ref.get_mut() = 32; //~ ERROR: Data race detected between (1) Atomic Load on thread `<unnamed>` and (2) Write on thread `<unnamed>`
+            *atomic_ref.get_mut() = 32; //~ ERROR: Data race detected between (1) atomic load on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>`
        });

        j1.join().unwrap();
--- a/src/tools/miri/tests/fail/data_race/atomic_read_na_write_race2.stderr
+++ b/src/tools/miri/tests/fail/data_race/atomic_read_na_write_race2.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Atomic Load on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) atomic load on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/atomic_read_na_write_race2.rs:LL:CC
   |
 LL |             *atomic_ref.get_mut() = 32;
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) Atomic Load on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) atomic load on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/atomic_read_na_write_race2.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/atomic_write_na_read_race1.rs
+++ b/src/tools/miri/tests/fail/data_race/atomic_write_na_read_race1.rs
@ -25,7 +25,7 @@ pub fn main() {
        let j2 = spawn(move || {
            let c = c; // avoid field capturing
            let atomic_ref = &mut *c.0;
-            *atomic_ref.get_mut() //~ ERROR: Data race detected between (1) Atomic Store on thread `<unnamed>` and (2) Read on thread `<unnamed>`
+            *atomic_ref.get_mut() //~ ERROR: Data race detected between (1) atomic store on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>`
        });

        j1.join().unwrap();
--- a/src/tools/miri/tests/fail/data_race/atomic_write_na_read_race1.stderr
+++ b/src/tools/miri/tests/fail/data_race/atomic_write_na_read_race1.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Atomic Store on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) atomic store on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/atomic_write_na_read_race1.rs:LL:CC
   |
 LL |             *atomic_ref.get_mut()
-   |             ^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) Atomic Store on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) atomic store on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/atomic_write_na_read_race1.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/atomic_write_na_read_race2.rs
+++ b/src/tools/miri/tests/fail/data_race/atomic_write_na_read_race2.rs
@ -22,7 +22,7 @@ pub fn main() {

        let j2 = spawn(move || {
            let c = c; // avoid field capturing
-            (&*c.0).store(32, Ordering::SeqCst); //~ ERROR: Data race detected between (1) Read on thread `<unnamed>` and (2) Atomic Store on thread `<unnamed>`
+            (&*c.0).store(32, Ordering::SeqCst); //~ ERROR: Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) atomic store on thread `<unnamed>`
        });

        j1.join().unwrap();
--- a/src/tools/miri/tests/fail/data_race/atomic_write_na_read_race2.stderr
+++ b/src/tools/miri/tests/fail/data_race/atomic_write_na_read_race2.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Read on thread `<unnamed>` and (2) Atomic Store on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) atomic store on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/atomic_write_na_read_race2.rs:LL:CC
   |
 LL |             (&*c.0).store(32, Ordering::SeqCst);
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) Read on thread `<unnamed>` and (2) Atomic Store on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) atomic store on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/atomic_write_na_read_race2.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/atomic_write_na_write_race1.rs
+++ b/src/tools/miri/tests/fail/data_race/atomic_write_na_write_race1.rs
@ -22,7 +22,7 @@ pub fn main() {

        let j2 = spawn(move || {
            let c = c; // avoid field capturing
-            (&*c.0).store(64, Ordering::SeqCst); //~ ERROR: Data race detected between (1) Write on thread `<unnamed>` and (2) Atomic Store on thread `<unnamed>`
+            (&*c.0).store(64, Ordering::SeqCst); //~ ERROR: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) atomic store on thread `<unnamed>`
        });

        j1.join().unwrap();
--- a/src/tools/miri/tests/fail/data_race/atomic_write_na_write_race1.stderr
+++ b/src/tools/miri/tests/fail/data_race/atomic_write_na_write_race1.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Atomic Store on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) atomic store on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/atomic_write_na_write_race1.rs:LL:CC
   |
 LL |             (&*c.0).store(64, Ordering::SeqCst);
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) Write on thread `<unnamed>` and (2) Atomic Store on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) atomic store on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/atomic_write_na_write_race1.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/atomic_write_na_write_race2.rs
+++ b/src/tools/miri/tests/fail/data_race/atomic_write_na_write_race2.rs
@ -25,7 +25,7 @@ pub fn main() {
        let j2 = spawn(move || {
            let c = c; // avoid field capturing
            let atomic_ref = &mut *c.0;
-            *atomic_ref.get_mut() = 32; //~ ERROR: Data race detected between (1) Atomic Store on thread `<unnamed>` and (2) Write on thread `<unnamed>`
+            *atomic_ref.get_mut() = 32; //~ ERROR: Data race detected between (1) atomic store on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>`
        });

        j1.join().unwrap();
--- a/src/tools/miri/tests/fail/data_race/atomic_write_na_write_race2.stderr
+++ b/src/tools/miri/tests/fail/data_race/atomic_write_na_write_race2.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Atomic Store on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) atomic store on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/atomic_write_na_write_race2.rs:LL:CC
   |
 LL |             *atomic_ref.get_mut() = 32;
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) Atomic Store on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) atomic store on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/atomic_write_na_write_race2.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/dangling_thread_async_race.rs
+++ b/src/tools/miri/tests/fail/data_race/dangling_thread_async_race.rs
@ -36,7 +36,7 @@ fn main() {
    let join2 = unsafe {
        spawn(move || {
            let c = c; // capture `c`, not just its field.
-            *c.0 = 64; //~ ERROR: Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `<unnamed>`
+            *c.0 = 64; //~ ERROR: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>`
        })
    };

--- a/src/tools/miri/tests/fail/data_race/dangling_thread_async_race.stderr
+++ b/src/tools/miri/tests/fail/data_race/dangling_thread_async_race.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/dangling_thread_async_race.rs:LL:CC
   |
 LL |             *c.0 = 64;
-   |             ^^^^^^^^^ Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/dangling_thread_async_race.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/dangling_thread_race.rs
+++ b/src/tools/miri/tests/fail/data_race/dangling_thread_race.rs
@ -34,6 +34,6 @@ fn main() {
    spawn(|| ()).join().unwrap();

    unsafe {
-        *c.0 = 64; //~ ERROR: Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `main`
+        *c.0 = 64; //~ ERROR: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `main`
    }
 }
--- a/src/tools/miri/tests/fail/data_race/dangling_thread_race.stderr
+++ b/src/tools/miri/tests/fail/data_race/dangling_thread_race.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `main` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `main` at ALLOC. (2) just happened here
  --> $DIR/dangling_thread_race.rs:LL:CC
   |
 LL |         *c.0 = 64;
-   |         ^^^^^^^^^ Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `main` at ALLOC. (2) just happened here
+   |         ^^^^^^^^^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `main` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/dangling_thread_race.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/dealloc_read_race1.rs
+++ b/src/tools/miri/tests/fail/data_race/dealloc_read_race1.rs
@ -27,7 +27,7 @@ pub fn main() {
        let j2 = spawn(move || {
            let ptr = ptr; // avoid field capturing
            __rust_dealloc(
-                //~^ ERROR: Data race detected between (1) Read on thread `<unnamed>` and (2) Deallocate on thread `<unnamed>`
+                //~^ ERROR: Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) deallocation on thread `<unnamed>`
                ptr.0 as *mut _,
                std::mem::size_of::<usize>(),
                std::mem::align_of::<usize>(),
--- a/src/tools/miri/tests/fail/data_race/dealloc_read_race1.stderr
+++ b/src/tools/miri/tests/fail/data_race/dealloc_read_race1.stderr
@ -1,4 +1,4 @@
-error: Undefined Behavior: Data race detected between (1) Read on thread `<unnamed>` and (2) Deallocate on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) deallocation on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/dealloc_read_race1.rs:LL:CC
   |
 LL | /             __rust_dealloc(
@ -7,7 +7,7 @@ LL | |                 ptr.0 as *mut _,
 LL | |                 std::mem::size_of::<usize>(),
 LL | |                 std::mem::align_of::<usize>(),
 LL | |             );
-   | |_____________^ Data race detected between (1) Read on thread `<unnamed>` and (2) Deallocate on thread `<unnamed>` at ALLOC. (2) just happened here
+   | |_____________^ Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) deallocation on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/dealloc_read_race1.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/dealloc_read_race2.rs
+++ b/src/tools/miri/tests/fail/data_race/dealloc_read_race2.rs
@ -30,7 +30,7 @@ pub fn main() {

        let j2 = spawn(move || {
            let ptr = ptr; // avoid field capturing
-            // Also an error of the form: Data race detected between (1) Deallocate on thread `<unnamed>` and (2) Read on thread `<unnamed>`
+            // Also an error of the form: Data race detected between (1) deallocation on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>`
            // but the invalid allocation is detected first.
            *ptr.0 //~ ERROR: has been freed
        });
--- a/src/tools/miri/tests/fail/data_race/dealloc_read_race_stack.rs
+++ b/src/tools/miri/tests/fail/data_race/dealloc_read_race_stack.rs
@ -36,7 +36,7 @@ pub fn main() {
                sleep(Duration::from_millis(200));

                // Now `stack_var` gets deallocated.
-            } //~ ERROR: Data race detected between (1) Read on thread `<unnamed>` and (2) Deallocate on thread `<unnamed>`
+            } //~ ERROR: Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) deallocation on thread `<unnamed>`
        });

        let j2 = spawn(move || {
--- a/src/tools/miri/tests/fail/data_race/dealloc_read_race_stack.stderr
+++ b/src/tools/miri/tests/fail/data_race/dealloc_read_race_stack.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Read on thread `<unnamed>` and (2) Deallocate on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) deallocation on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/dealloc_read_race_stack.rs:LL:CC
   |
 LL |             }
-   |             ^ Data race detected between (1) Read on thread `<unnamed>` and (2) Deallocate on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^ Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) deallocation on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/dealloc_read_race_stack.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/dealloc_write_race1.rs
+++ b/src/tools/miri/tests/fail/data_race/dealloc_write_race1.rs
@ -26,7 +26,7 @@ pub fn main() {
        let j2 = spawn(move || {
            let ptr = ptr; // avoid field capturing
            __rust_dealloc(
-                //~^ ERROR: Data race detected between (1) Write on thread `<unnamed>` and (2) Deallocate on thread `<unnamed>`
+                //~^ ERROR: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) deallocation on thread `<unnamed>`
                ptr.0 as *mut _,
                std::mem::size_of::<usize>(),
                std::mem::align_of::<usize>(),
--- a/src/tools/miri/tests/fail/data_race/dealloc_write_race1.stderr
+++ b/src/tools/miri/tests/fail/data_race/dealloc_write_race1.stderr
@ -1,4 +1,4 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Deallocate on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) deallocation on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/dealloc_write_race1.rs:LL:CC
   |
 LL | /             __rust_dealloc(
@ -7,7 +7,7 @@ LL | |                 ptr.0 as *mut _,
 LL | |                 std::mem::size_of::<usize>(),
 LL | |                 std::mem::align_of::<usize>(),
 LL | |             );
-   | |_____________^ Data race detected between (1) Write on thread `<unnamed>` and (2) Deallocate on thread `<unnamed>` at ALLOC. (2) just happened here
+   | |_____________^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) deallocation on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/dealloc_write_race1.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/dealloc_write_race2.rs
+++ b/src/tools/miri/tests/fail/data_race/dealloc_write_race2.rs
@ -29,7 +29,7 @@ pub fn main() {

        let j2 = spawn(move || {
            let ptr = ptr; // avoid field capturing
-            // Also an error of the form: Data race detected between (1) Deallocate on thread `<unnamed>` and (2) Write on thread `<unnamed>`
+            // Also an error of the form: Data race detected between (1) deallocation on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>`
            // but the invalid allocation is detected first.
            *ptr.0 = 2; //~ ERROR: has been freed
        });
--- a/src/tools/miri/tests/fail/data_race/dealloc_write_race_stack.rs
+++ b/src/tools/miri/tests/fail/data_race/dealloc_write_race_stack.rs
@ -36,7 +36,7 @@ pub fn main() {
                sleep(Duration::from_millis(200));

                // Now `stack_var` gets deallocated.
-            } //~ ERROR: Data race detected between (1) Write on thread `<unnamed>` and (2) Deallocate on thread `<unnamed>`
+            } //~ ERROR: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) deallocation on thread `<unnamed>`
        });

        let j2 = spawn(move || {
--- a/src/tools/miri/tests/fail/data_race/dealloc_write_race_stack.stderr
+++ b/src/tools/miri/tests/fail/data_race/dealloc_write_race_stack.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Deallocate on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) deallocation on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/dealloc_write_race_stack.rs:LL:CC
   |
 LL |             }
-   |             ^ Data race detected between (1) Write on thread `<unnamed>` and (2) Deallocate on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) deallocation on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/dealloc_write_race_stack.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/enable_after_join_to_main.rs
+++ b/src/tools/miri/tests/fail/data_race/enable_after_join_to_main.rs
@ -32,7 +32,7 @@ pub fn main() {

        let j2 = spawn(move || {
            let c = c; // avoid field capturing
-            *c.0 = 64; //~ ERROR: Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `<unnamed>`
+            *c.0 = 64; //~ ERROR: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>`
        });

        j1.join().unwrap();
--- a/src/tools/miri/tests/fail/data_race/enable_after_join_to_main.stderr
+++ b/src/tools/miri/tests/fail/data_race/enable_after_join_to_main.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/enable_after_join_to_main.rs:LL:CC
   |
 LL |             *c.0 = 64;
-   |             ^^^^^^^^^ Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/enable_after_join_to_main.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/fence_after_load.rs
+++ b/src/tools/miri/tests/fail/data_race/fence_after_load.rs
@ -20,5 +20,5 @@ fn main() {
    // The fence is useless, since it did not happen-after the `store` in the other thread.
    // Hence this is a data race.
    // Also see https://github.com/rust-lang/miri/issues/2192.
-    unsafe { V = 2 } //~ERROR: Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `main`
+    unsafe { V = 2 } //~ERROR: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `main`
 }
--- a/src/tools/miri/tests/fail/data_race/fence_after_load.stderr
+++ b/src/tools/miri/tests/fail/data_race/fence_after_load.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `main` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `main` at ALLOC. (2) just happened here
  --> $DIR/fence_after_load.rs:LL:CC
   |
 LL |     unsafe { V = 2 }
-   |              ^^^^^ Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `main` at ALLOC. (2) just happened here
+   |              ^^^^^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `main` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/fence_after_load.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/mixed_size_read.rs
+++ b/src/tools/miri/tests/fail/data_race/mixed_size_read.rs
@ -19,7 +19,7 @@ fn main() {
        });
        s.spawn(|| {
            a8[0].load(Ordering::SeqCst);
-            //~^ ERROR: Race condition detected between (1) 2-byte Atomic Load on thread `<unnamed>` and (2) 1-byte (different-size) Atomic Load on thread `<unnamed>`
+            //~^ ERROR: Race condition detected between (1) 2-byte atomic load on thread `<unnamed>` and (2) 1-byte atomic load on thread `<unnamed>`
        });
    });
 }
--- a/src/tools/miri/tests/fail/data_race/mixed_size_read.stderr
+++ b/src/tools/miri/tests/fail/data_race/mixed_size_read.stderr
@ -1,14 +1,15 @@
-error: Undefined Behavior: Race condition detected between (1) 2-byte Atomic Load on thread `<unnamed>` and (2) 1-byte (different-size) Atomic Load on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Race condition detected between (1) 2-byte atomic load on thread `<unnamed>` and (2) 1-byte atomic load on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/mixed_size_read.rs:LL:CC
   |
 LL |             a8[0].load(Ordering::SeqCst);
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Race condition detected between (1) 2-byte Atomic Load on thread `<unnamed>` and (2) 1-byte (different-size) Atomic Load on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Race condition detected between (1) 2-byte atomic load on thread `<unnamed>` and (2) 1-byte atomic load on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/mixed_size_read.rs:LL:CC
   |
 LL |             a16.load(Ordering::SeqCst);
   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = help: overlapping unsynchronized atomic accesses must use the same access size
   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
   = note: BACKTRACE (of the first span):
--- a/src/tools/miri/tests/fail/data_race/mixed_size_write.rs
+++ b/src/tools/miri/tests/fail/data_race/mixed_size_write.rs
@ -19,7 +19,7 @@ fn main() {
        });
        s.spawn(|| {
            a8[0].store(1, Ordering::SeqCst);
-            //~^ ERROR: Race condition detected between (1) 2-byte Atomic Store on thread `<unnamed>` and (2) 1-byte (different-size) Atomic Store on thread `<unnamed>`
+            //~^ ERROR: Race condition detected between (1) 2-byte atomic store on thread `<unnamed>` and (2) 1-byte atomic store on thread `<unnamed>`
        });
    });
 }
--- a/src/tools/miri/tests/fail/data_race/mixed_size_write.stderr
+++ b/src/tools/miri/tests/fail/data_race/mixed_size_write.stderr
@ -1,14 +1,15 @@
-error: Undefined Behavior: Race condition detected between (1) 2-byte Atomic Store on thread `<unnamed>` and (2) 1-byte (different-size) Atomic Store on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Race condition detected between (1) 2-byte atomic store on thread `<unnamed>` and (2) 1-byte atomic store on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/mixed_size_write.rs:LL:CC
   |
 LL |             a8[0].store(1, Ordering::SeqCst);
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Race condition detected between (1) 2-byte Atomic Store on thread `<unnamed>` and (2) 1-byte (different-size) Atomic Store on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Race condition detected between (1) 2-byte atomic store on thread `<unnamed>` and (2) 1-byte atomic store on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/mixed_size_write.rs:LL:CC
   |
 LL |             a16.store(1, Ordering::SeqCst);
   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = help: overlapping unsynchronized atomic accesses must use the same access size
   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
   = note: BACKTRACE (of the first span):
--- a/src/tools/miri/tests/fail/data_race/read_read_race1.rs
+++ b/src/tools/miri/tests/fail/data_race/read_read_race1.rs
@ -21,7 +21,7 @@ fn main() {
            unsafe { ptr.read() };
            // Then do the atomic access.
            a.load(Ordering::SeqCst);
-            //~^ ERROR: Data race detected between (1) Read on thread `<unnamed>` and (2) Atomic Load on thread `<unnamed>`
+            //~^ ERROR: Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) atomic load on thread `<unnamed>`
        });
    });
 }
--- a/src/tools/miri/tests/fail/data_race/read_read_race1.stderr
+++ b/src/tools/miri/tests/fail/data_race/read_read_race1.stderr
@ -1,14 +1,15 @@
-error: Undefined Behavior: Data race detected between (1) Read on thread `<unnamed>` and (2) Atomic Load on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) atomic load on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/read_read_race1.rs:LL:CC
   |
 LL |             a.load(Ordering::SeqCst);
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) Read on thread `<unnamed>` and (2) Atomic Load on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^ Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) atomic load on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/read_read_race1.rs:LL:CC
   |
 LL |             unsafe { ptr.read() };
   |                      ^^^^^^^^^^
+   = help: overlapping atomic and non-atomic accesses must be synchronized, even if both are read-only
   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
   = note: BACKTRACE (of the first span):
--- a/src/tools/miri/tests/fail/data_race/read_read_race2.rs
+++ b/src/tools/miri/tests/fail/data_race/read_read_race2.rs
@ -21,7 +21,7 @@ fn main() {

            let ptr = &a as *const AtomicU16 as *mut u16;
            unsafe { ptr.read() };
-            //~^ ERROR: Data race detected between (1) Atomic Load on thread `<unnamed>` and (2) Read on thread `<unnamed>`
+            //~^ ERROR: Data race detected between (1) atomic load on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>`
        });
    });
 }
--- a/src/tools/miri/tests/fail/data_race/read_read_race2.stderr
+++ b/src/tools/miri/tests/fail/data_race/read_read_race2.stderr
@ -1,14 +1,15 @@
-error: Undefined Behavior: Data race detected between (1) Atomic Load on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) atomic load on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/read_read_race2.rs:LL:CC
   |
 LL |             unsafe { ptr.read() };
-   |                      ^^^^^^^^^^ Data race detected between (1) Atomic Load on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+   |                      ^^^^^^^^^^ Data race detected between (1) atomic load on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/read_read_race2.rs:LL:CC
   |
 LL |             a.load(Ordering::SeqCst);
   |             ^^^^^^^^^^^^^^^^^^^^^^^^
+   = help: overlapping atomic and non-atomic accesses must be synchronized, even if both are read-only
   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
   = note: BACKTRACE (of the first span):
--- a/src/tools/miri/tests/fail/data_race/read_write_race.rs
+++ b/src/tools/miri/tests/fail/data_race/read_write_race.rs
@ -21,7 +21,7 @@ pub fn main() {

        let j2 = spawn(move || {
            let c = c; // avoid field capturing
-            *c.0 = 64; //~ ERROR: Data race detected between (1) Read on thread `<unnamed>` and (2) Write on thread `<unnamed>`
+            *c.0 = 64; //~ ERROR: Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>`
        });

        j1.join().unwrap();
--- a/src/tools/miri/tests/fail/data_race/read_write_race.stderr
+++ b/src/tools/miri/tests/fail/data_race/read_write_race.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Read on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/read_write_race.rs:LL:CC
   |
 LL |             *c.0 = 64;
-   |             ^^^^^^^^^ Data race detected between (1) Read on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^ Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/read_write_race.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/read_write_race_stack.rs
+++ b/src/tools/miri/tests/fail/data_race/read_write_race_stack.rs
@ -40,7 +40,7 @@ pub fn main() {

            sleep(Duration::from_millis(200));

-            stack_var //~ ERROR: Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>`
+            stack_var //~ ERROR: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>`
        });

        let j2 = spawn(move || {
--- a/src/tools/miri/tests/fail/data_race/read_write_race_stack.stderr
+++ b/src/tools/miri/tests/fail/data_race/read_write_race_stack.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/read_write_race_stack.rs:LL:CC
   |
 LL |             stack_var
-   |             ^^^^^^^^^ Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/read_write_race_stack.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/relax_acquire_race.rs
+++ b/src/tools/miri/tests/fail/data_race/relax_acquire_race.rs
@ -39,7 +39,7 @@ pub fn main() {
        let j3 = spawn(move || {
            let c = c; // avoid field capturing
            if SYNC.load(Ordering::Acquire) == 2 {
-                *c.0 //~ ERROR: Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>`
+                *c.0 //~ ERROR: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>`
            } else {
                0
            }
--- a/src/tools/miri/tests/fail/data_race/relax_acquire_race.stderr
+++ b/src/tools/miri/tests/fail/data_race/relax_acquire_race.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/relax_acquire_race.rs:LL:CC
   |
 LL |                 *c.0
-   |                 ^^^^ Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+   |                 ^^^^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/relax_acquire_race.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/release_seq_race.rs
+++ b/src/tools/miri/tests/fail/data_race/release_seq_race.rs
@ -43,7 +43,7 @@ pub fn main() {
            let c = c; // avoid field capturing
            sleep(Duration::from_millis(500));
            if SYNC.load(Ordering::Acquire) == 3 {
-                *c.0 //~ ERROR: Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>`
+                *c.0 //~ ERROR: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>`
            } else {
                0
            }
--- a/src/tools/miri/tests/fail/data_race/release_seq_race.stderr
+++ b/src/tools/miri/tests/fail/data_race/release_seq_race.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/release_seq_race.rs:LL:CC
   |
 LL |                 *c.0
-   |                 ^^^^ Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+   |                 ^^^^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/release_seq_race.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/release_seq_race_same_thread.rs
+++ b/src/tools/miri/tests/fail/data_race/release_seq_race_same_thread.rs
@ -39,7 +39,7 @@ pub fn main() {
        let j2 = spawn(move || {
            let c = c; // avoid field capturing
            if SYNC.load(Ordering::Acquire) == 2 {
-                *c.0 //~ ERROR: Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>`
+                *c.0 //~ ERROR: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>`
            } else {
                0
            }
--- a/src/tools/miri/tests/fail/data_race/release_seq_race_same_thread.stderr
+++ b/src/tools/miri/tests/fail/data_race/release_seq_race_same_thread.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/release_seq_race_same_thread.rs:LL:CC
   |
 LL |                 *c.0
-   |                 ^^^^ Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+   |                 ^^^^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/release_seq_race_same_thread.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/rmw_race.rs
+++ b/src/tools/miri/tests/fail/data_race/rmw_race.rs
@ -40,7 +40,7 @@ pub fn main() {
        let j3 = spawn(move || {
            let c = c; // capture `c`, not just its field.
            if SYNC.load(Ordering::Acquire) == 3 {
-                *c.0 //~ ERROR: Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>`
+                *c.0 //~ ERROR: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>`
            } else {
                0
            }
--- a/src/tools/miri/tests/fail/data_race/rmw_race.stderr
+++ b/src/tools/miri/tests/fail/data_race/rmw_race.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/rmw_race.rs:LL:CC
   |
 LL |                 *c.0
-   |                 ^^^^ Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>` at ALLOC. (2) just happened here
+   |                 ^^^^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic read on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/rmw_race.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/stack_pop_race.rs
+++ b/src/tools/miri/tests/fail/data_race/stack_pop_race.rs
@ -21,4 +21,4 @@ fn race(local: i32) {
    // Deallocating the local (when `main` returns)
    // races with the read in the other thread.
    // Make sure the error points at this function's end, not just the call site.
-} //~ERROR: Data race detected between (1) Read on thread `<unnamed>` and (2) Deallocate on thread `main`
+} //~ERROR: Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) deallocation on thread `main`
--- a/src/tools/miri/tests/fail/data_race/stack_pop_race.stderr
+++ b/src/tools/miri/tests/fail/data_race/stack_pop_race.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Read on thread `<unnamed>` and (2) Deallocate on thread `main` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) deallocation on thread `main` at ALLOC. (2) just happened here
  --> $DIR/stack_pop_race.rs:LL:CC
   |
 LL | }
-   |  ^ Data race detected between (1) Read on thread `<unnamed>` and (2) Deallocate on thread `main` at ALLOC. (2) just happened here
+   |  ^ Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) deallocation on thread `main` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/stack_pop_race.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/write_write_race.rs
+++ b/src/tools/miri/tests/fail/data_race/write_write_race.rs
@ -21,7 +21,7 @@ pub fn main() {

        let j2 = spawn(move || {
            let c = c; // avoid field capturing
-            *c.0 = 64; //~ ERROR: Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `<unnamed>`
+            *c.0 = 64; //~ ERROR: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>`
        });

        j1.join().unwrap();
--- a/src/tools/miri/tests/fail/data_race/write_write_race.stderr
+++ b/src/tools/miri/tests/fail/data_race/write_write_race.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/write_write_race.rs:LL:CC
   |
 LL |             *c.0 = 64;
-   |             ^^^^^^^^^ Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/write_write_race.rs:LL:CC
--- a/src/tools/miri/tests/fail/data_race/write_write_race_stack.rs
+++ b/src/tools/miri/tests/fail/data_race/write_write_race_stack.rs
@ -40,7 +40,7 @@ pub fn main() {

            sleep(Duration::from_millis(200));

-            stack_var = 1usize; //~ ERROR: Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `<unnamed>`
+            stack_var = 1usize; //~ ERROR: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>`

            // read to silence errors
            stack_var
--- a/src/tools/miri/tests/fail/data_race/write_write_race_stack.stderr
+++ b/src/tools/miri/tests/fail/data_race/write_write_race_stack.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/write_write_race_stack.rs:LL:CC
   |
 LL |             stack_var = 1usize;
-   |             ^^^^^^^^^^^^^^^^^^ Data race detected between (1) Write on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^^^^^^^^^^ Data race detected between (1) non-atomic write on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/write_write_race_stack.rs:LL:CC
--- a/src/tools/miri/tests/fail/stacked_borrows/retag_data_race_protected_read.rs
+++ b/src/tools/miri/tests/fail/stacked_borrows/retag_data_race_protected_read.rs
@ -13,7 +13,7 @@ fn main() {
        let ptr = ptr;
        // We do a protected mutable retag (but no write!) in this thread.
        fn retag(_x: &mut i32) {}
-        retag(unsafe { &mut *ptr.0 }); //~ERROR: Data race detected between (1) Read on thread `main` and (2) Write on thread `<unnamed>`
+        retag(unsafe { &mut *ptr.0 }); //~ERROR: Data race detected between (1) non-atomic read on thread `main` and (2) non-atomic write on thread `<unnamed>`
    });

    // We do a read in the main thread.
--- a/src/tools/miri/tests/fail/stacked_borrows/retag_data_race_protected_read.stderr
+++ b/src/tools/miri/tests/fail/stacked_borrows/retag_data_race_protected_read.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Read on thread `main` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic read on thread `main` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/retag_data_race_protected_read.rs:LL:CC
   |
 LL |         retag(unsafe { &mut *ptr.0 });
-   |                        ^^^^^^^^^^^ Data race detected between (1) Read on thread `main` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+   |                        ^^^^^^^^^^^ Data race detected between (1) non-atomic read on thread `main` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/retag_data_race_protected_read.rs:LL:CC
--- a/src/tools/miri/tests/fail/stacked_borrows/retag_data_race_read.rs
+++ b/src/tools/miri/tests/fail/stacked_borrows/retag_data_race_read.rs
@ -15,7 +15,7 @@ fn thread_1(p: SendPtr) {
 fn thread_2(p: SendPtr) {
    let p = p.0;
    unsafe {
-        *p = 5; //~ ERROR: Data race detected between (1) Read on thread `<unnamed>` and (2) Write on thread `<unnamed>`
+        *p = 5; //~ ERROR: Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>`
    }
 }

--- a/src/tools/miri/tests/fail/stacked_borrows/retag_data_race_read.stderr
+++ b/src/tools/miri/tests/fail/stacked_borrows/retag_data_race_read.stderr
@ -1,8 +1,8 @@
-error: Undefined Behavior: Data race detected between (1) Read on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/retag_data_race_read.rs:LL:CC
   |
 LL |         *p = 5;
-   |         ^^^^^^ Data race detected between (1) Read on thread `<unnamed>` and (2) Write on thread `<unnamed>` at ALLOC. (2) just happened here
+   |         ^^^^^^ Data race detected between (1) non-atomic read on thread `<unnamed>` and (2) non-atomic write on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/retag_data_race_read.rs:LL:CC
--- a/src/tools/miri/tests/fail/weak_memory/racing_mixed_size.rs
+++ b/src/tools/miri/tests/fail/weak_memory/racing_mixed_size.rs
@ -31,7 +31,7 @@ pub fn main() {
        let x_split = split_u32_ptr(x_ptr);
        unsafe {
            let hi = ptr::addr_of!((*x_split)[0]);
-            std::intrinsics::atomic_load_relaxed(hi); //~ ERROR: different-size
+            std::intrinsics::atomic_load_relaxed(hi); //~ ERROR: (1) 4-byte atomic store on thread `<unnamed>` and (2) 2-byte atomic load
        }
    });

--- a/src/tools/miri/tests/fail/weak_memory/racing_mixed_size.stderr
+++ b/src/tools/miri/tests/fail/weak_memory/racing_mixed_size.stderr
@ -1,14 +1,15 @@
-error: Undefined Behavior: Race condition detected between (1) 4-byte Atomic Store on thread `<unnamed>` and (2) 2-byte (different-size) Atomic Load on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Race condition detected between (1) 4-byte atomic store on thread `<unnamed>` and (2) 2-byte atomic load on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/racing_mixed_size.rs:LL:CC
   |
 LL |             std::intrinsics::atomic_load_relaxed(hi);
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Race condition detected between (1) 4-byte Atomic Store on thread `<unnamed>` and (2) 2-byte (different-size) Atomic Load on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Race condition detected between (1) 4-byte atomic store on thread `<unnamed>` and (2) 2-byte atomic load on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/racing_mixed_size.rs:LL:CC
   |
 LL |         x.store(1, Relaxed);
   |         ^^^^^^^^^^^^^^^^^^^
+   = help: overlapping unsynchronized atomic accesses must use the same access size
   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
   = note: BACKTRACE (of the first span):
--- a/src/tools/miri/tests/fail/weak_memory/racing_mixed_size_read.rs
+++ b/src/tools/miri/tests/fail/weak_memory/racing_mixed_size_read.rs
@ -29,7 +29,7 @@ pub fn main() {
        let x_split = split_u32_ptr(x_ptr);
        unsafe {
            let hi = x_split as *const u16 as *const AtomicU16;
-            (*hi).load(Relaxed); //~ ERROR: different-size
+            (*hi).load(Relaxed); //~ ERROR: (1) 4-byte atomic load on thread `<unnamed>` and (2) 2-byte atomic load
        }
    });

--- a/src/tools/miri/tests/fail/weak_memory/racing_mixed_size_read.stderr
+++ b/src/tools/miri/tests/fail/weak_memory/racing_mixed_size_read.stderr
@ -1,14 +1,15 @@
-error: Undefined Behavior: Race condition detected between (1) 4-byte Atomic Load on thread `<unnamed>` and (2) 2-byte (different-size) Atomic Load on thread `<unnamed>` at ALLOC. (2) just happened here
+error: Undefined Behavior: Race condition detected between (1) 4-byte atomic load on thread `<unnamed>` and (2) 2-byte atomic load on thread `<unnamed>` at ALLOC. (2) just happened here
  --> $DIR/racing_mixed_size_read.rs:LL:CC
   |
 LL |             (*hi).load(Relaxed);
-   |             ^^^^^^^^^^^^^^^^^^^ Race condition detected between (1) 4-byte Atomic Load on thread `<unnamed>` and (2) 2-byte (different-size) Atomic Load on thread `<unnamed>` at ALLOC. (2) just happened here
+   |             ^^^^^^^^^^^^^^^^^^^ Race condition detected between (1) 4-byte atomic load on thread `<unnamed>` and (2) 2-byte atomic load on thread `<unnamed>` at ALLOC. (2) just happened here
   |
 help: and (1) occurred earlier here
  --> $DIR/racing_mixed_size_read.rs:LL:CC
   |
 LL |         x.load(Relaxed);
   |         ^^^^^^^^^^^^^^^
+   = help: overlapping unsynchronized atomic accesses must use the same access size
   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
   = note: BACKTRACE (of the first span):