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From: David Laight <David.Laight@ACULAB.COM>
To: 'Linus Torvalds' <torvalds@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Alexander Popov <alex.popov@linux.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"Ingo Molnar" <mingo@kernel.org>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Tycho Andersen <tycho@tycho.ws>,
	"Mark Rutland" <mark.rutland@arm.com>,
	Laura Abbott <labbott@redhat.com>,
	"Will Deacon" <will.deacon@arm.com>
Subject: RE: [GIT PULL] gcc-plugin updates for v4.19-rc1
Date: Thu, 16 Aug 2018 09:51:41 +0000	[thread overview]
Message-ID: <8d9dd1f35af1463dbeaf03c9d028020b@AcuMS.aculab.com> (raw)
In-Reply-To: <CA+55aFy6jNLsywVYdGp83AMrXBo_P-pkjkphPGrO=82SPKCpLQ@mail.gmail.com>

From: Linus Torvalds
> Sent: 15 August 2018 21:19
...
> But if people run things on real machines, then BUG() is absolutely
> the last thing you EVER want to do for "debugging".

I'm not sure you want it on a live system either.
Live systems are where the 'hard' bugs show up.

I've just spent a couple of days pulling my hair out trying to work
out how to debug a customer system that was locking up solid when
running some new (and not completely testable by us) kernel code.

At 4am I suddenly realised that the distribution they are using
might be enabling 'panic_on_oops' by default.
Turning that off showed what was going wrong.

It wouldn't be as bad if Linux implemented 'dump to swap'.

For 'errors' that aren't completely fatal the system could
'fast shutdown' a lot of processes (maybe just refuse to schedule
them) while leaving enough running for fault diagnosis.
I'm not sure how you'd decide what to allow to run though.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

      parent reply	other threads:[~2018-08-16  9:50 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-13 21:43 Kees Cook
2018-08-15 16:41 ` Linus Torvalds
2018-08-15 18:35   ` Kees Cook
2018-08-15 19:04     ` Linus Torvalds
2018-08-15 19:43       ` Alexander Popov
2018-08-15 19:45       ` Kees Cook
2018-08-15 20:18         ` Linus Torvalds
2018-08-15 20:56           ` Kees Cook
2018-08-15 21:18             ` Alexander Popov
2018-08-15 21:33               ` Linus Torvalds
2018-08-16 22:18             ` Alexander Popov
2018-08-16  9:51           ` David Laight [this message]

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