bug#39962: 27.0.90; Crash in Emacs 27.0.90

[Pip Cet]

On Wed, Mar 11, 2020 at 8:03 PM Pieter van Oostrum
<pieter-l@vanoostrum.org> wrote:
> With this patch I still get a crash. This time a sementation violation again 
> in the garbage collector. So that doesn't solve the problem I am encountering.

It's not always the same crash, is it? That one looks like it might be
a stack overflow.

> Thread 3 received signal SIGSEGV, Segmentation fault.

Thread 3 is the main thread? What does "i thr" say, if gdb supports it on MacOS?

> 0x00000001002b5000 in vector_marked_p (v=0x160249fd0) at alloc.c:3715
> 3715      if (pdumper_object_p (v))
> (gdb) bt 10
> #0  0x00000001002b5000 in vector_marked_p (v=0x160249fd0) at alloc.c:3715
> #1  0x00000001002b369f in mark_object (arg=XIL(0x160249fd5)) at alloc.c:6480
> #2  0x00000001002b5813 in mark_vectorlike (header=0x160249f50) at alloc.c:6157
> #3  0x00000001002b391a in mark_object (arg=XIL(0x160249f55)) at alloc.c:6566
> #4  0x00000001002b5813 in mark_vectorlike (header=0x160249e60) at alloc.c:6157
> #5  0x00000001002b391a in mark_object (arg=XIL(0x160249e65)) at alloc.c:6566
> #6  0x00000001002b3d33 in mark_object (arg=XIL(0x167929583)) at alloc.c:6628
> #7  0x00000001002b3b04 in mark_object (arg=XIL(0x515dcd0)) at alloc.c:6585
> #8  0x00000001002b5813 in mark_vectorlike (header=0x11ddd20f0) at alloc.c:6157
> #9  0x00000001002b391a in mark_object (arg=XIL(0x11ddd20f5)) at alloc.c:6566
> (More stack frames follow...)
> Warning:
> Cannot insert breakpoint 0.
> Cannot access memory at address 0x7ffeef270f7f

My guess is 0x7ffeef270000 is your stack's guard page... Can you print
$rsp to confirm?