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Subject: Re: [PATCH] coredump: Limit what can interrupt coredumps
From: Olivier Langlois <olivier@trillion01.com>
To: Jens Axboe <axboe@kernel.dk>,
Tony Battersby <tonyb@cybernetics.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
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io-uring <io-uring@vger.kernel.org>,
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"Pavel Begunkov>" <asml.silence@gmail.com>
Date: Sat, 21 Aug 2021 12:47:23 -0400
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On Sat, 2021-08-21 at 06:08 -0400, Olivier Langlois wrote:
> On Tue, 2021-08-17 at 20:57 -0600, Jens Axboe wrote:
> >
> > Olivier, I sent a 5.10 version for Nathan, any chance you can test
> > this
> > one for the current kernels? Basically this one should work for
> > 5.11+,
> > and the later 5.10 version is just for 5.10. I'm going to send it
> > out
> > separately for review.
> >
> > I do think this is the right solution, barring a tweak maybe on
> > testing
> > notify == TWA_SIGNAL first before digging into the task struct. But
> > the
> > principle is sound, and it'll work for other users of TWA_SIGNAL as
> > well. None right now as far as I can tell, but the live patching is
> > switching to TIF_NOTIFY_SIGNAL as well which will also cause issues
> > with
> > coredumps potentially.
> >
> Ok, I am going to give it a shot. This solution is probably superior
> to
> the previous attempt as it does not inject io_uring dependency into
> the
> coredump module.
>
> The small extra change that I alluded to in my previous reply will
> still be relevant even if we go with your patch...
>
> I'll come back soon with your patch testing result and my small extra
> change that I keep teasing about.
>
> Greetings,
>
Jens,
your patch doesn't compile with 5.12+. AFAIK, the reason is that
JOBCTL_TASK_WORK is gone.
Wouldn't just a call to tracehook_notify_signal from do_coredump be
enough and backward compatible with every possible stable branches?
Greetings,