From: William Lee Irwin III <wli@holomorphy.com>
To: Andrew Morton <akpm@osdl.org>
Cc: Keith Owens <kaos@sgi.com>, linux-kernel@vger.kernel.org
Subject: Re: [patch 2.6.7] bug_smp_call_function
Date: Sat, 19 Jun 2004 02:59:10 -0700 [thread overview]
Message-ID: <20040619095910.GQ1863@holomorphy.com> (raw)
In-Reply-To: <20040619024416.065f4026.akpm@osdl.org>
Keith Owens <kaos@sgi.com> wrote:
>> sg.c has been fixed to no longer call vfree() with interrupts disabled.
>> Change smp_call_function() from WARN_ON to BUG_ON when interrupts are
>> disabled. It was only set to WARN_ON because of sg.c.
On Sat, Jun 19, 2004 at 02:44:16AM -0700, Andrew Morton wrote:
> I prefer the WARN_ON. It is exceedingly unlikely that the bug will cause
> lockups or memory/data corruption or anything else, so why nuke the user's
> box when we can trivially continue?
> We'll be sent the bug report either way.
Calls to smp_call_function() with interrupts off or spinlocks held
typically causes deadlocks on SMP systems. ISTR debugging such an
issue in the scheduler a while back, i.e. mmdrop() under rq->lock
doing vfree() of an LDT. Basically smp_call_function() will spin
waiting for the other cpus to answer the interrupt on multiple cpus.
It also doesn't need to be the same function doing smp_call_function();
generally TLB flushing deadlocks against anything doing this.
-- wli
next prev parent reply other threads:[~2004-06-19 10:00 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-06-19 9:36 [patch 2.6.7] bug_smp_call_function Keith Owens
2004-06-19 9:44 ` Andrew Morton
2004-06-19 9:54 ` Keith Owens
2004-06-19 9:59 ` William Lee Irwin III [this message]
2004-06-19 10:05 ` Keith Owens
2004-06-19 10:08 ` Andrew Morton
2004-06-19 10:14 ` William Lee Irwin III
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