On Tue, 2021-08-17 at 12:15 -0600, Jens Axboe wrote:

It does indeed sound like it's TIF_NOTIFY_SIGNAL that will trigger
some
signal_pending() and cause an interruption of the core dump. Just out
of
curiosity, what is your /proc/sys/kernel/core_pattern set to? If it's
set to some piped process, can you try and set it to 'core' and see
if
that eliminates the truncation of the core dumps for your case?

/proc/sys/kernel/core_pattern is set to:
|/home/lano1106/bin/pipe_core.sh %e %p

It normally points to systemd coredump module. I have pointed to a
simpler program for debugging purposes.

when core_pattern points to a local file, core dump files are just
fine. That was the whole point of 

commit 06af8679449d ("coredump: Limit what can interrupt coredumps")

I have been distracted by other things this week but my last attempt to
fix this problem appears to be successful. I will send out a small
patch set shortly...