Invalid integer to pointer cast with segafult on Windows

[seijikun]

I am the author of the kmeans crate and I got reports about segfaults on Windows.

To get to the bottom of the problem, I ran one of the project's examples through Miri, which promptly complained about an invalid integer-to-pointer cast in crossbeam-epoch.
Miri complains in both: Linux and Windows, but the segfaults only happen with Windows. Under Linux, there is no segfault and the results of the calculations seem to be correct.

I am not a pro in reading Miri reports, but it at least looks to me like the problem lies with crossbeam. I only have one small piece of unsafe in kmeans but I couldn't find any error with it.

Here is a minimal reproduction project: segfaultrepro.zip
Running cargo miri run in it shows the following report:

warning: integer-to-pointer cast
   --> /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/atomic.rs:204:11
    |
204 |         &*(ptr as *const T)
    |           ^^^^^^^^^^^^^^^^^ integer-to-pointer cast
    |
    = help: this program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`, which means that Miri might miss pointer bugs in this program
    = help: see https://doc.rust-lang.org/nightly/std/ptr/fn.with_exposed_provenance.html for more details on that operation
    = help: to ensure that Miri does not miss bugs in your program, use Strict Provenance APIs (https://doc.rust-lang.org/nightly/std/ptr/index.html#strict-provenance, https://crates.io/crates/sptr) instead
    = help: you can then set `MIRIFLAGS=-Zmiri-strict-provenance` to ensure you are not relying on `with_exposed_provenance` semantics
    = help: alternatively, `MIRIFLAGS=-Zmiri-permissive-provenance` disables this warning
    = note: BACKTRACE on thread `unnamed-1`:
    = note: inside `<crossbeam_epoch::internal::Local as crossbeam_epoch::atomic::Pointable>::deref::<'_>` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/atomic.rs:204:11: 204:28
    = note: inside `crossbeam_epoch::atomic::Shared::<'_, crossbeam_epoch::internal::Local>::deref` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/atomic.rs:1421:9: 1421:22
    = note: inside `crossbeam_epoch::sync::list::List::<crossbeam_epoch::internal::Local>::insert` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/sync/list.rs:176:41: 176:58
    = note: inside `crossbeam_epoch::internal::Local::register` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/internal.rs:330:13: 330:65
    = note: inside `crossbeam_epoch::collector::Collector::register` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/collector.rs:45:9: 45:30
    = note: inside `crossbeam_epoch::default::HANDLE::__init` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/default.rs:34:34: 34:56
    = note: inside `<fn() -> crossbeam_epoch::collector::LocalHandle {crossbeam_epoch::default::HANDLE::__init} as std::ops::FnOnce<()>>::call_once - shim(fn() -> crossbeam_epoch::collector::LocalHandle {crossbeam_epoch::default::HANDLE::__init})` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5: 250:71
    = note: inside `std::option::Option::<crossbeam_epoch::collector::LocalHandle>::unwrap_or_else::<fn() -> crossbeam_epoch::collector::LocalHandle {crossbeam_epoch::default::HANDLE::__init}>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/option.rs:1017:21: 1017:24
    = note: inside `std::thread::local_impl::LazyStorage::<crossbeam_epoch::collector::LocalHandle, ()>::initialize::<fn() -> crossbeam_epoch::collector::LocalHandle {crossbeam_epoch::default::HANDLE::__init}>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/thread_local/native/lazy.rs:64:17: 64:59
    = note: inside `std::thread::local_impl::LazyStorage::<crossbeam_epoch::collector::LocalHandle, ()>::get_or_init::<fn() -> crossbeam_epoch::collector::LocalHandle {crossbeam_epoch::default::HANDLE::__init}>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/thread_local/native/lazy.rs:56:40: 56:61
    = note: inside closure at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/thread_local/native/mod.rs:94:25: 94:54
    = note: inside `<{closure@crossbeam_epoch::default::HANDLE::{constant#0}::{closure#0}} as std::ops::FnOnce<(std::option::Option<&mut std::option::Option<crossbeam_epoch::collector::LocalHandle>>,)>>::call_once - shim` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5: 250:71
    = note: inside `std::thread::LocalKey::<crossbeam_epoch::collector::LocalHandle>::try_with::<{closure@crossbeam_epoch::default::with_handle<{closure@crossbeam_epoch::default::is_pinned::{closure#0}}, bool>::{closure#0}}, bool>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/thread/local.rs:282:37: 282:55
    = note: inside `crossbeam_epoch::default::with_handle::<{closure@crossbeam_epoch::default::is_pinned::{closure#0}}, bool>` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/default.rs:59:5: 60:28
    = note: inside `crossbeam_epoch::default::is_pinned` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/default.rs:46:5: 46:45
    = note: inside `crossbeam_deque::deque::Stealer::<rayon_core::job::JobRef>::steal` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-deque-0.8.5/src/deque.rs:641:12: 641:30
    = note: inside `rayon_core::registry::WorkerThread::take_local_job` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:751:19: 751:39
    = note: inside `rayon_core::registry::WorkerThread::wait_until_cold` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:785:32: 785:53
    = note: inside `rayon_core::registry::WorkerThread::wait_until::<rayon_core::latch::OnceLatch>` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:769:13: 769:40
    = note: inside `rayon_core::registry::WorkerThread::wait_until_out_of_work` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:818:9: 818:65
    = note: inside `rayon_core::registry::main_loop` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:923:5: 923:43
    = note: inside `rayon_core::registry::ThreadBuilder::run` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:53:18: 53:33
    = note: inside closure at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:98:20: 98:32
    = note: inside `std::sys::backtrace::__rust_begin_short_backtrace::<{closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/backtrace.rs:154:18: 154:21
    = note: inside closure at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/thread/mod.rs:541:17: 541:71
    = note: inside `<std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>::{closure#1}::{closure#0}}> as std::ops::FnOnce<()>>::call_once` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/panic/unwind_safe.rs:272:9: 272:19
    = note: inside `std::panicking::r#try::do_call::<std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>::{closure#1}::{closure#0}}>, ()>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:557:40: 557:43
    = note: inside `std::panicking::r#try::<(), std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>::{closure#1}::{closure#0}}>>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:520:19: 520:88
    = note: inside `std::panic::catch_unwind::<std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>::{closure#1}::{closure#0}}>, ()>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panic.rs:358:14: 358:33
    = note: inside closure at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/thread/mod.rs:540:30: 542:16
    = note: inside `<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>::{closure#1}} as std::ops::FnOnce<()>>::call_once - shim(vtable)` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5: 250:71
    = note: inside `<std::boxed::Box<dyn std::ops::FnOnce()> as std::ops::FnOnce<()>>::call_once` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1968:9: 1968:52
    = note: inside `<std::boxed::Box<std::boxed::Box<dyn std::ops::FnOnce()>> as std::ops::FnOnce<()>>::call_once` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1968:9: 1968:52
    = note: inside `std::sys::pal::unix::thread::Thread::new::thread_start` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/pal/unix/thread.rs:105:17: 105:64

warning: integer-to-pointer cast
    --> /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/atomic.rs:1345:9
     |
1345 |         raw as *const _
     |         ^^^^^^^^^^^^^^^ integer-to-pointer cast
     |
     = note: BACKTRACE on thread `unnamed-1`:
     = note: inside `crossbeam_epoch::atomic::Shared::<'_, crossbeam_epoch::internal::Local>::as_raw` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/atomic.rs:1345:9: 1345:24
     = note: inside `crossbeam_epoch::internal::Local::register` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/internal.rs:332:24: 332:38
     = note: inside `crossbeam_epoch::collector::Collector::register` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/collector.rs:45:9: 45:30
     = note: inside `crossbeam_epoch::default::HANDLE::__init` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/default.rs:34:34: 34:56
     = note: inside `<fn() -> crossbeam_epoch::collector::LocalHandle {crossbeam_epoch::default::HANDLE::__init} as std::ops::FnOnce<()>>::call_once - shim(fn() -> crossbeam_epoch::collector::LocalHandle {crossbeam_epoch::default::HANDLE::__init})` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5: 250:71
     = note: inside `std::option::Option::<crossbeam_epoch::collector::LocalHandle>::unwrap_or_else::<fn() -> crossbeam_epoch::collector::LocalHandle {crossbeam_epoch::default::HANDLE::__init}>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/option.rs:1017:21: 1017:24
     = note: inside `std::thread::local_impl::LazyStorage::<crossbeam_epoch::collector::LocalHandle, ()>::initialize::<fn() -> crossbeam_epoch::collector::LocalHandle {crossbeam_epoch::default::HANDLE::__init}>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/thread_local/native/lazy.rs:64:17: 64:59
     = note: inside `std::thread::local_impl::LazyStorage::<crossbeam_epoch::collector::LocalHandle, ()>::get_or_init::<fn() -> crossbeam_epoch::collector::LocalHandle {crossbeam_epoch::default::HANDLE::__init}>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/thread_local/native/lazy.rs:56:40: 56:61
     = note: inside closure at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/thread_local/native/mod.rs:94:25: 94:54
     = note: inside `<{closure@crossbeam_epoch::default::HANDLE::{constant#0}::{closure#0}} as std::ops::FnOnce<(std::option::Option<&mut std::option::Option<crossbeam_epoch::collector::LocalHandle>>,)>>::call_once - shim` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5: 250:71
     = note: inside `std::thread::LocalKey::<crossbeam_epoch::collector::LocalHandle>::try_with::<{closure@crossbeam_epoch::default::with_handle<{closure@crossbeam_epoch::default::is_pinned::{closure#0}}, bool>::{closure#0}}, bool>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/thread/local.rs:282:37: 282:55
     = note: inside `crossbeam_epoch::default::with_handle::<{closure@crossbeam_epoch::default::is_pinned::{closure#0}}, bool>` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/default.rs:59:5: 60:28
     = note: inside `crossbeam_epoch::default::is_pinned` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/default.rs:46:5: 46:45
     = note: inside `crossbeam_deque::deque::Stealer::<rayon_core::job::JobRef>::steal` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-deque-0.8.5/src/deque.rs:641:12: 641:30
     = note: inside `rayon_core::registry::WorkerThread::take_local_job` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:751:19: 751:39
     = note: inside `rayon_core::registry::WorkerThread::wait_until_cold` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:785:32: 785:53
     = note: inside `rayon_core::registry::WorkerThread::wait_until::<rayon_core::latch::OnceLatch>` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:769:13: 769:40
     = note: inside `rayon_core::registry::WorkerThread::wait_until_out_of_work` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:818:9: 818:65
     = note: inside `rayon_core::registry::main_loop` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:923:5: 923:43
     = note: inside `rayon_core::registry::ThreadBuilder::run` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:53:18: 53:33
     = note: inside closure at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:98:20: 98:32
     = note: inside `std::sys::backtrace::__rust_begin_short_backtrace::<{closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/backtrace.rs:154:18: 154:21
     = note: inside closure at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/thread/mod.rs:541:17: 541:71
     = note: inside `<std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>::{closure#1}::{closure#0}}> as std::ops::FnOnce<()>>::call_once` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/panic/unwind_safe.rs:272:9: 272:19
     = note: inside `std::panicking::r#try::do_call::<std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>::{closure#1}::{closure#0}}>, ()>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:557:40: 557:43
     = note: inside `std::panicking::r#try::<(), std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>::{closure#1}::{closure#0}}>>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:520:19: 520:88
     = note: inside `std::panic::catch_unwind::<std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>::{closure#1}::{closure#0}}>, ()>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panic.rs:358:14: 358:33
     = note: inside closure at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/thread/mod.rs:540:30: 542:16
     = note: inside `<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>::{closure#1}} as std::ops::FnOnce<()>>::call_once - shim(vtable)` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5: 250:71
     = note: inside `<std::boxed::Box<dyn std::ops::FnOnce()> as std::ops::FnOnce<()>>::call_once` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1968:9: 1968:52
     = note: inside `<std::boxed::Box<std::boxed::Box<dyn std::ops::FnOnce()>> as std::ops::FnOnce<()>>::call_once` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1968:9: 1968:52
     = note: inside `std::sys::pal::unix::thread::Thread::new::thread_start` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/pal/unix/thread.rs:105:17: 105:64

error: Undefined Behavior: trying to retag from <115679> for SharedReadWrite permission at alloc54434[0x8], but that tag does not exist in the borrow stack for this location
   --> /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/internal.rs:549:9
    |
549 |         &*local_ptr
    |         ^^^^^^^^^^^
    |         |
    |         trying to retag from <115679> for SharedReadWrite permission at alloc54434[0x8], but that tag does not exist in the borrow stack for this location
    |         this error occurs as part of retag at alloc54434[0x0..0x180]
    |
    = help: this indicates a potential bug in the program: it performed an invalid operation, but the Stacked Borrows rules it violated are still experimental
    = help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information
help: <115679> was created by a SharedReadWrite retag at offsets [0x0..0x8]
   --> /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/internal.rs:548:26
    |
548 |         let local_ptr = (entry as *const Entry).cast::<Self>();
    |                          ^^^^^
    = note: BACKTRACE (of the first span) on thread `unnamed-1`:
    = note: inside `<crossbeam_epoch::internal::Local as crossbeam_epoch::sync::list::IsElement<crossbeam_epoch::internal::Local>>::element_of` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/internal.rs:549:9: 549:20
    = note: inside `<crossbeam_epoch::sync::list::Iter<'_, crossbeam_epoch::internal::Local, crossbeam_epoch::internal::Local> as std::iter::Iterator>::next` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/sync/list.rs:290:37: 290:53
    = note: inside `crossbeam_epoch::internal::Global::try_advance` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/internal.rs:235:22: 235:45
    = note: inside `crossbeam_epoch::internal::Global::collect` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/internal.rs:200:28: 200:51
    = note: inside `crossbeam_epoch::internal::Local::pin` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/internal.rs:435:17: 435:46
    = note: inside `crossbeam_epoch::collector::LocalHandle::pin` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/collector.rs:81:18: 81:37
    = note: inside closure at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/default.rs:40:26: 40:38
    = note: inside closure at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/default.rs:60:23: 60:27
    = note: inside `std::thread::LocalKey::<crossbeam_epoch::collector::LocalHandle>::try_with::<{closure@crossbeam_epoch::default::with_handle<{closure@crossbeam_epoch::default::pin::{closure#0}}, crossbeam_epoch::guard::Guard>::{closure#0}}, crossbeam_epoch::guard::Guard>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/thread/local.rs:283:12: 283:27
    = note: inside `crossbeam_epoch::default::with_handle::<{closure@crossbeam_epoch::default::pin::{closure#0}}, crossbeam_epoch::guard::Guard>` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/default.rs:59:5: 60:28
    = note: inside `crossbeam_epoch::default::pin` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.18/src/default.rs:40:5: 40:39
    = note: inside `crossbeam_deque::deque::Stealer::<rayon_core::job::JobRef>::steal` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-deque-0.8.5/src/deque.rs:645:22: 645:34
    = note: inside `rayon_core::registry::WorkerThread::take_local_job` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:751:19: 751:39
    = note: inside `rayon_core::registry::WorkerThread::wait_until_cold` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:785:32: 785:53
    = note: inside `rayon_core::registry::WorkerThread::wait_until::<rayon_core::latch::OnceLatch>` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:769:13: 769:40
    = note: inside `rayon_core::registry::WorkerThread::wait_until_out_of_work` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:818:9: 818:65
    = note: inside `rayon_core::registry::main_loop` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:923:5: 923:43
    = note: inside `rayon_core::registry::ThreadBuilder::run` at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:53:18: 53:33
    = note: inside closure at /home/seiji/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rayon-core-1.12.1/src/registry.rs:98:20: 98:32
    = note: inside `std::sys::backtrace::__rust_begin_short_backtrace::<{closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/backtrace.rs:154:18: 154:21
    = note: inside closure at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/thread/mod.rs:541:17: 541:71
    = note: inside `<std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>::{closure#1}::{closure#0}}> as std::ops::FnOnce<()>>::call_once` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/panic/unwind_safe.rs:272:9: 272:19
    = note: inside `std::panicking::r#try::do_call::<std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>::{closure#1}::{closure#0}}>, ()>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:557:40: 557:43
    = note: inside `std::panicking::r#try::<(), std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>::{closure#1}::{closure#0}}>>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:520:19: 520:88
    = note: inside `std::panic::catch_unwind::<std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>::{closure#1}::{closure#0}}>, ()>` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panic.rs:358:14: 358:33
    = note: inside closure at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/thread/mod.rs:540:30: 542:16
    = note: inside `<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@<rayon_core::registry::DefaultSpawn as rayon_core::registry::ThreadSpawn>::spawn::{closure#0}}, ()>::{closure#1}} as std::ops::FnOnce<()>>::call_once - shim(vtable)` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5: 250:71
    = note: inside `<std::boxed::Box<dyn std::ops::FnOnce()> as std::ops::FnOnce<()>>::call_once` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1968:9: 1968:52
    = note: inside `<std::boxed::Box<std::boxed::Box<dyn std::ops::FnOnce()>> as std::ops::FnOnce<()>>::call_once` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1968:9: 1968:52
    = note: inside `std::sys::pal::unix::thread::Thread::new::thread_start` at /home/seiji/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/pal/unix/thread.rs:105:17: 105:64

error: aborting due to 1 previous error; 2 warnings emitted

[taiki-e]

The ptr2int issue has been resolved in master, and crossbeam-epoch is not compatible with SB, but only with TB (#545). Could you tell us what error you get when you use -Zmiri-tree-borrows with the master branch of crossbeam?

[taiki-e]

I only have one small piece of unsafe in kmeans but I couldn't find any error with it.

The following two line:

https://github.com/seijikun/kmean-rs/blob/f8eab6f4cd12ac3cb54ae5b1ff76fa54472be87b/src/memory.rs#L83-L84

let aligned_ptr = alloc_zeroed(layout) as *mut T;
let resvec = Vec::from_raw_parts(aligned_ptr, size, size);

alloc_zeroed returns null pointer when allocation failed. Your code is unsound because it does not handle that case.

[seijikun]

Awesome, thank you so much for the quick reply and help!
When I patch the dependency to master:

[patch.crates-io]
crossbeam = { git = "https://github.com/crossbeam-rs/crossbeam.git" }
crossbeam-epoch = { git = "https://github.com/crossbeam-rs/crossbeam.git" }

and run with MIRIFLAGS="-Zmiri-tree-borrows" cargo miri run
The miri complaints inside crossbeam go away.

---

alloc_zeroed returns null pointer when allocation failed. Your code is unsound because it does not handle that case.

Oh, thanks for the heads up! Will fix that.
With the crossbeam errors gone, I also saw that deallocation of the Vec doesn't work properly either, since it tries to dealloc with the wrong alignment 😅