Segfault upon stack overflow in child thread. #7490
Comments
|
Comment author: @mshinwell I will have a look at this |
|
Comment author: @mshinwell Pierre and I are working on a fix. |
|
Comment author: @mshinwell Please see #1062 |
|
Fixed by #8670 . |
samoht
added a commit
to samoht/index
that referenced
this issue
Nov 20, 2019
To avoid allocating on the stack, keep the runtime lock so that OCaml objects are not moved around. This is needed because thread stack are very small on musl<1.1.21 (80k). Allocating a buffer of 64k bytes on the stack means that the stack overflow detection (`caml_c_call`) won't have enough space to allocate 32k and will segfault: see ocaml/ocaml#7490 for a similar bug report. `caml_c_call` has been properly fixed in behttps://github.com/ocaml/ocaml/pull/8670 and it also has been changed to only allocate 4k -- also solving our initial issue with too small thread stacks (as 64+8<80). Many thanks to @sadiqj for helping with debugging the issue. Co-authored-by: Frédéric Bour <fred@tarides.com>
gs0510
pushed a commit
to gs0510/index
that referenced
this issue
Dec 6, 2019
To avoid allocating on the stack, keep the runtime lock so that OCaml objects are not moved around. This is needed because thread stack are very small on musl<1.1.21 (80k). Allocating a buffer of 64k bytes on the stack means that the stack overflow detection (`caml_c_call`) won't have enough space to allocate 32k and will segfault: see ocaml/ocaml#7490 for a similar bug report. `caml_c_call` has been properly fixed in behttps://github.com/ocaml/ocaml/pull/8670 and it also has been changed to only allocate 4k -- also solving our initial issue with too small thread stacks (as 64+8<80). Many thanks to @sadiqj for helping with debugging the issue. Co-authored-by: Frédéric Bour <fred@tarides.com>
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Original bug ID: 7490
Reporter: wintersteiger
Assigned to: @mshinwell
Status: assigned (set by @mshinwell on 2017-02-24T14:39:24Z)
Resolution: open
Priority: normal
Severity: crash
Platform: amd64
OS: Ubuntu
OS Version: 16.04
Version: 4.04.0
Category: threads
Monitored by: @gasche
Bug description
This works as expected:
let rec thread_fun _ =
try
thread_fun ()
with
Stack_overflow -> Printf.printf "caught exn\n"
let _ = thread_fun () ; ()
But when thread_fun is called like so:
let _ =
Thread.join (Thread.create thread_fun ()) ;
()
then it segfaults.
Steps to reproduce
Compile with ocamlopt -thread unix.cmxa threads.cmxa stackoverflow.ml -o stackoverflow
Run ./stackoverflow
Additional information
Problem originally encountered in FStar, see here: FStarLang/FStar#870
The text was updated successfully, but these errors were encountered: