bug#39962: 27.0.90; Crash in Emacs 27.0.90

[Pip Cet]

On Thu, Mar 19, 2020 at 1:23 PM Pieter van Oostrum
<pieter-l@vanoostrum.org> wrote:
> (gdb) p ((Lisp_Object) {(Lisp_Word) (0xd4269c0)})
> $5 = XIL(0xd4269c0)
> (gdb) xsymbol
> $6 = (struct Lisp_Symbol *) 0x10de5f6d0
> "<v>"

Okay, so that symbol is valid.

I think it's not a coincidence this crash happens during
keyboard/mouse input. I'm attaching a patch which increases the window
for the race condition that I think is happening. It slows down Emacs
significantly, but it should still be almost usable.

If you have the time, could you install the patch, start Emacs the
same way you did to produce your original crash, and do similar things
you did that time? If we're lucky, we'll be getting an assert failure
rather than mere corruption.

0001-more-debugging.patch
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