> Could you possibly bisect the 1.65.1 git branch and determine

> precisely which commit causes the problem?

Turns out valgrind had a typo that mistakingly reports epoll_pwait()

with a NULL sigmask as an error, and glibc happens to have a

condition to invoke epoll_pwait() for calls to epoll_wait(), filling

sigmask with NULL.

The error has been fixed but not yet released

(https://sourceware.org/git/?p=valgrind.git;a=commit;h=3ac87cf9277964802ddd9af9747a10ff0b838c29).

Thanks for your attention.