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From: Andrew Morton <akpm@zip.com.au>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Manfred Spraul <manfred@colorfullife.com>,
	linux-kernel@vger.kernel.org,
	Marcelo Tosatti <marcelo@conectiva.com.br>
Subject: Re: [patch] block/IDE/interrupt lockup
Date: Sat, 30 Mar 2002 11:06:25 -0800	[thread overview]
Message-ID: <3CA60CB1.E33080D5@zip.com.au> (raw)
In-Reply-To: <3CA603B0.8B73FD4C@zip.com.au> from "Andrew Morton" at Mar 30, 2002 10:28:00 AM <E16rNxa-0003UM-00@the-village.bc.nu>

Alan Cox wrote:
> 
> > The kernel calls request_irq() inside cli() in lots of places.
> > That's the same bug: "if you called cli(), how come you're
> > allowing kmalloc to clear it?".
> 
> Those places should if possible be fixed. I take patches. If we can get 2.4
> to BUG() on those kmalloc violations and clean them up it sounds like
> progress

What I'd like is a debugging function `can_sleep()'.  This
is good for documentary purposes, and will catch bugs.

So kmalloc() would gain:

	if (gfp_flags & __GFP_WAIT)
		can_sleep();

can_sleep() would do the following:

- If CONFIG_PREEMPT, check the locking depth (minus BKL depth),
  whine if non-zero.

- If inside cli(), whine.

- If inside __cli(), also whine (not really a bug, but a design error).

- whining will include generation of a backtrace.

I suspect a 2.4 version would generate too many bug reports :)
It would have to implement its own lock depth accounting if
we want the sleep-inside-spinlock checking.

There's some arch-dependent stuff in there.  I'll do a 2.5
patch.  I suspect it'll generate showers of stuff.  We can
feed fixes back into 2.4.

-

  reply	other threads:[~2002-03-30 19:08 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-03-30  9:35 [patch] block/IDE/interrupt lockup Manfred Spraul
2002-03-30 18:28 ` Andrew Morton
2002-03-30 18:52   ` Alan Cox
2002-03-30 19:06     ` Andrew Morton [this message]
2002-03-30 23:23       ` Keith Owens
  -- strict thread matches above, loose matches on Subject: below --
2002-04-01  9:23 Manfred Spraul
2002-03-30  5:45 Andrew Morton

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