[Bug 298878] linux(4): epoll_pwait(2)/epoll_pwait2(2) with a sigmask leave a stale signal mask, deadlocking Bun apps (Claude Code, opencode)

From: <bugzilla-noreply_at_freebsd.org>
Date: Sun, 27 Sep 2026 18:54:11 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=298878

--- Comment #5 from Todd Smith <todd.c.smith@gmail.com> ---
Confirming the fix on amd64.

Setup: ThinkPad T14s Gen 2a (Ryzen 7 PRO 5850U), FreeBSD 15.1-RELEASE-p3 amd64,
linux_base-c7, Claude Code native Linux binary (Bun).

 Before: every Claude Code session from 2.1.282 on froze within 0–90 s (11 of
11 sessions on 2026-09-24). The process stayed alive at ~0 % CPU and input was
ignored. 2.1.281 was usable, though it presumably has the same exposure at a
lower rate. Downstream report:
https://github.com/anthropics/claude-code/issues/96931

 Patch: I applied the same change as attachment 275145 (the code is identical,
only the comment wording differs) to releng/15.1, then rebuilt and installed
linux64.ko and linux.ko.

 After: with the patched modules loaded, Claude Code 2.1.283 has run for over 7
minutes of normal interactive use without freezing, with no Bun/JSC workaround
environment variables set. Before the patch, 2.1.282 never lasted past 90 s.

Thanks to the reporter for the analysis and the patch.

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