From: Andrea Arcangeli <andrea@suse.de>
To: "David S. Miller" <davem@davemloft.net>
Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, akpm@osdl.org
Subject: Re: VM fixes [1/4]
Date: Fri, 24 Dec 2004 19:20:31 +0100 [thread overview]
Message-ID: <20041224182031.GG13747@dualathlon.random> (raw)
In-Reply-To: <20041224100016.530a004c.davem@davemloft.net>
On Fri, Dec 24, 2004 at 10:00:16AM -0800, David S. Miller wrote:
> On Fri, 24 Dec 2004 18:35:19 +0100
> Andrea Arcangeli <andrea@suse.de> wrote:
>
> > I made used_math a char at the light of later patches. per-cpu atomicity
> > with byte granularity is provided by all archs AFIK.
>
> Older Alpha's need to read-modify-write a word to implement
> byte ops.
Yep, I remeber this was the case in some old alpha. But did they support
smp too? I can't see how that old hardware could support smp. If they're
UP they're fine.
The race is extremely tiny anyway, you'd need to write to the
/proc/<pid>/ file at the same time that used_math is toggled.
Or alternatively you'd need to kill the task due oom at the same time
used_math is toggled.
The race in PF_MEMDIE is more serious.
And false sharing with memdie and oomkilladj is zero, since they're
pratically readonly.
next prev parent reply other threads:[~2004-12-24 18:21 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-24 17:35 VM fixes [1/4] Andrea Arcangeli
2004-12-24 18:00 ` David S. Miller
2004-12-24 18:20 ` Andrea Arcangeli [this message]
2004-12-24 18:41 ` Lee Revell
2004-12-24 18:48 ` Andrea Arcangeli
2004-12-24 18:52 ` Lee Revell
2004-12-25 4:40 ` Jeff Garzik
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