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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Thu, 10 Jun 2021 12:50:48 -0700
Message-ID: <CAHk-=wjPiEaXjUp6PTcLZFjT8RrYX+ExtD-RY3NjFWDN7mKLbw@mail.gmail.com>
Subject: Re: [CFT}[PATCH] coredump: Limit what can interrupt coredumps
To:     "Eric W. Biederman" <ebiederm@xmission.com>
Cc:     Olivier Langlois <olivier@trillion01.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        io-uring <io-uring@vger.kernel.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Jens Axboe <axboe@kernel.dk>,
        "Pavel Begunkov>" <asml.silence@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>
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On Thu, Jun 10, 2021 at 12:18 PM Eric W. Biederman
<ebiederm@xmission.com> wrote:
>
> I just didn't want those two lines hiding any other issues we might
> have in the coredumps.
>
> That is probably better development thinking than minimal fix thinking.

Well, I think we should first do the minimal targeted fix (the part in
fs/coredump.c).

Then we should look at whether we could do cleanups as a result of that fix.

And I suspect the cleanups might bigger than the two-liner removal.
The whole SIGNAL_GROUP_COREDUMP flag was introduced for this issue,

See commit 403bad72b67d ("coredump: only SIGKILL should interrupt the
coredumping task") which introduced this all.

Now, we have since grown other users of SIGNAL_GROUP_COREDUMP - OOM
hanmdling and the clear_child_tid thing in mm_release(). So maybe we
should keep SIGNAL_GROUP_COREDUMP around.

So maybe only those two lines end up being the ones to remove, but I'd
really like to think of it as a separate thing from the fix itself.

                Linus