Blocking MVar# primops not performing stack checks?

Carter Schonwald carter.schonwald at
Mon Mar 2 05:27:26 UTC 2020

The simplest way to answer this is if you can help us construct a program,
whether as Haskell or cmm, which tickles the failure you suspect is there ?

The rts definitely gets less love overall.  And there’s fewer folks
involved in those layers overall.

On Wed, Feb 26, 2020 at 10:03 AM Shao, Cheng <cheng.shao at> wrote:

> Hi all,
> When an MVar# primop blocks, it jumps to a function in
> HeapStackCheck.cmm which pushes a RET_SMALL stack frame before
> returning to the scheduler (e.g. the takeMVar# primop jumps to
> stg_block_takemvar for stack adjustment). But these functions directly
> bump Sp without checking for possible stack overflow, I wonder if it
> is a bug?
> Cheers,
> Cheng
> _______________________________________________
> ghc-devs mailing list
> ghc-devs at
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the ghc-devs mailing list