I think that this is a bug in the 5.10 kernel. I just hit it on a previously working cgit host by upgrading the kernel from 5.9.15 to 5.10.4. Downgrading the kernel back to 5.9.15 fixes it.
I'm guessing it was broken by 36e2c7421f02 ("fs: don't allow splice
read/write without explicit ops") because if I crank up kernel logging I
get:
splice write not supported for file (pid: 2522 comm: cgit.cgi)
--
Jon
Doge Wrangler
X(7): A program for managing terminal windows. See also screen(1) and tmux(1).
