Comments (4)
As far as I can tell, zeroed_box
, which is try_zeroed_box
with an unwrap
, can't possibly be using more than 5 or 6 usize
worth of stack space itself. So the allocator must be doing something funky.
I'm putting you on the case!
from bytemuck.
So, I'm currently guessing there is undefined behavior in play. This repoduces the issue standalone:
use std::alloc;
use std::mem::{size_of, align_of, zeroed};
use std::alloc::{alloc_zeroed, Layout};
#[inline]
pub fn try_zeroed_box<T>() -> Result<Box<T>, ()> {
if size_of::<T>() == 0 {
return Ok(Box::new(unsafe{zeroed()}));
}
let layout =
Layout::from_size_align(size_of::<T>(), align_of::<T>()).unwrap();
let ptr = unsafe { alloc_zeroed(layout) };
if ptr.is_null() {
// we don't know what the error is because `alloc_zeroed` is a dumb API
Err(())
} else {
Ok(unsafe { Box::<T>::from_raw(ptr as *mut T) })
}
}
const PAGE_SIZE: usize = 4096;
type BlockChunk = [u8; PAGE_SIZE];
const MIB_16: usize = 16 * 1024 * 1024;
const SUPER_SIZE: usize = MIB_16 / std::mem::size_of::<BlockChunk>();
type SuperPage = [BlockChunk; SUPER_SIZE];
fn main() {
// ABORT: thread '[...]::test_alloc' has overflowed its stack
let _: Box<SuperPage> = try_zeroed_box().unwrap();
}
Note in particual these lines:
if size_of::<T>() == 0 {
return Ok(Box::new(unsafe{zeroed()}));
}
I'm guessing that this somehow is undefined behavior if expanded with a very large T
from bytemuck.
Actually its perfectly well define beheavior - its a normal branch, which contains a temporary stack variable that needs to be allocated in the stack frame. So the issue is just how to avoid it.
from bytemuck.
Fixed by #43
from bytemuck.
Related Issues (20)
- `ASSERT_SIZE_MULTIPLE_OF` when casting `&[u8]` to `&[[u8; 16]]` HOT 1
- Crate documentation is misleading, implies `Pod` required for all functions. HOT 3
- the `FooBits` type generated by `#[derive(CheckedBitPattern)]` should implement `NoUninit` if `Self` is `NoUninit` HOT 3
- False positive derive error for `TransparentWrapper` around types like `Box` HOT 1
- Potential rustc bug related to deriving ByteEq HOT 2
- no-uninit trait with interior mutability HOT 6
- Deriving Pod for arbitrary generic types HOT 1
- Why use from_bytes when you can use pod_read_unaligned? HOT 5
- Build error on nightly-2024-02-05 HOT 1
- Bytemuck 1.14.2 does not build on stable HOT 1
- Feature request: Casting owned slices or vec, I.e. Box<[u64]> to Box<[u8]> or Vec<u64> to Vec<u8> HOT 4
- conversion from `&[u8]` to `&[T]`? HOT 4
- Allow deriving `Zeroable` for enums which are `#[repr(u32, i8, etc..)]` HOT 2
- Address safety invariants in documentation HOT 1
- No documentation for the FooBits public type generated by derive(CheckedBitPattern) HOT 1
- Casts and conversions for owned, boxed slices HOT 5
- `#[derive(TransparentWrapper)]` doesn't work with `where` clause generic bounds. HOT 1
- Unsound usages of unsafe implementation from different generics HOT 2
- Unsound usages of unsafe implementation from `[u8]` to `T` HOT 2
- impl `ZeroableInOption` for all `Zeroable`? HOT 1
Recommend Projects
-
React
A declarative, efficient, and flexible JavaScript library for building user interfaces.
-
Vue.js
🖖 Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.
-
Typescript
TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
-
TensorFlow
An Open Source Machine Learning Framework for Everyone
-
Django
The Web framework for perfectionists with deadlines.
-
Laravel
A PHP framework for web artisans
-
D3
Bring data to life with SVG, Canvas and HTML. 📊📈🎉
-
Recommend Topics
-
javascript
JavaScript (JS) is a lightweight interpreted programming language with first-class functions.
-
web
Some thing interesting about web. New door for the world.
-
server
A server is a program made to process requests and deliver data to clients.
-
Machine learning
Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.
-
Visualization
Some thing interesting about visualization, use data art
-
Game
Some thing interesting about game, make everyone happy.
Recommend Org
-
Facebook
We are working to build community through open source technology. NB: members must have two-factor auth.
-
Microsoft
Open source projects and samples from Microsoft.
-
Google
Google ❤️ Open Source for everyone.
-
Alibaba
Alibaba Open Source for everyone
-
D3
Data-Driven Documents codes.
-
Tencent
China tencent open source team.
from bytemuck.