bug#53949: Setting (font-lock-mode 0) in very large buffers will cause highlight-symbol-at-point to fail to highlight all matches

[Dongli Si]

emacs version is 27.2 (Installed using dnf on fedora 35 system)

test file: https://github.com/torvalds/linux/blob/v5.16/kernel/events/core.c

Step1: emacs -Q kernel/events/core.c

Step2: eval "(font-lock-mode 0)"

Step3: eval "(highlight-regexp "static")"

The "static" keyword at the end of the file is not highlighted.