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From: Linus Torvalds <>
To: Peter Zijlstra <>
Cc: Andrew Morton <>,
	Linux Kernel Mailing List <>,
	Andy Lutomirski <>,
	Jens Axboe <>, Kees Cook <>,
	Jann Horn <>, Will Deacon <>
Subject: Re: [PATCH] mm/tlb: Fix use_mm() vs TLB invalidate
Date: Fri, 21 Feb 2020 11:19:22 -0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Fri, Feb 21, 2020 at 3:11 AM Peter Zijlstra <> wrote:
> +       BUG_ON(!(tsk->flags & PF_KTHREAD));
> +       BUG_ON(tsk->mm != NULL);

Stop this craziness.

There is absolutely ZERO excuse for this kind of garbage.

Making this a BUG_ON() will just cause all the possible debugging info
to be thrown away and lost, and you often have a dead machine.

For absolutely no good reason.

Make it a WARN_ON_ONCE(). If it triggers, everything works the way it
always did, but we get notified.

Stop with the stupid crazy BUG_ON() crap already. It is actively _bad_
for debugging.


  reply	other threads:[~2020-02-21 19:19 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-21 11:11 Peter Zijlstra
2020-02-21 19:19 ` Linus Torvalds [this message]
2020-02-21 19:22   ` Andy Lutomirski
2020-02-21 19:26     ` Linus Torvalds
2020-02-21 23:10     ` Kees Cook
2020-02-21 23:57       ` Linus Torvalds
2020-02-22  0:29         ` Kees Cook

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