linux-kernel - Re: [PATCH] coredump: Limit what can interrupt coredumps

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Date:   Sat, 21 Aug 2021 05:48:42 -0400
From:   Olivier Langlois <olivier@...llion01.com>
To:     Jens Axboe <axboe@...nel.dk>,
        Tony Battersby <tonyb@...ernetics.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Oleg Nesterov <oleg@...hat.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        io-uring <io-uring@...r.kernel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        "Pavel Begunkov>" <asml.silence@...il.com>
Subject: Re: [PATCH] coredump: Limit what can interrupt coredumps

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...