From: Peter Zijlstra <peterz@infradead.org>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>, r6144 <rainy6144@gmail.com>,
linux-kernel@vger.kernel.org, Darren Hart <dvhltc@us.ibm.com>,
tglx <tglx@linutronix.de>,
Lee Schermerhorn <lee.schermerhorn@hp.com>
Subject: Re: Process-shared futexes on hugepages puts the kernel in an infinite loop in 2.6.32.11; is this fixed now?
Date: Mon, 19 Apr 2010 18:18:48 +0200 [thread overview]
Message-ID: <1271693928.1676.18.camel@laptop> (raw)
In-Reply-To: <20100419161102.GZ32034@random.random>
On Mon, 2010-04-19 at 18:11 +0200, Andrea Arcangeli wrote:
> On Mon, Apr 19, 2010 at 05:45:05PM +0200, Peter Zijlstra wrote:
> > Wouldn't a longer poison be more recognisable? Also, shouldn't this use
> > POISON_POINTER_DELTA?
> >
> > Something like:
> >
> > #define HUGETBL_POISON ((void *) 0x00300300 + POISON_POINTER_DELTA)
> >
> > 0x2e5 isn't that high, I've had actual derefs in that range.
>
> The default at kernel config time sets only 4k as unmapped (I think
> it's a very bad default for 64bit archs), so above 4k userland can map
> it and you can have actual derefs with 0x00300300 but not with Mel's
> preferred <0x1000 address. So the address must be <0x1000.
Well, most poison values have that problem and still we have them. Also
on 64bit machines you can use POISON_POINTER_DELTA to map it outside the
virtual address range.
next prev parent reply other threads:[~2010-04-19 16:18 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-16 15:45 Process-shared futexes on hugepages puts the kernel in an infinite loop in 2.6.32.11; is this fixed now? r6144
2010-04-16 20:27 ` Peter Zijlstra
2010-04-19 11:43 ` Mel Gorman
2010-04-19 11:52 ` Peter Zijlstra
2010-04-19 15:32 ` Mel Gorman
2010-04-19 15:45 ` Peter Zijlstra
2010-04-19 16:11 ` Andrea Arcangeli
2010-04-19 16:18 ` Peter Zijlstra [this message]
2010-04-19 16:32 ` Andrea Arcangeli
2010-04-19 16:34 ` Mel Gorman
2010-04-19 15:48 ` Andrea Arcangeli
2010-04-19 16:04 ` Darren Hart
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