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From: Mike Galbraith <mikeg@wen-online.de>
To: Linus Torvalds <torvalds@transmeta.com>
Cc: Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Signal 11 - the continuing saga
Date: Thu, 14 Dec 2000 08:22:47 +0100 (CET)	[thread overview]
Message-ID: <Pine.Linu.4.10.10012140809180.1309-100000@mikeg.weiden.de> (raw)
In-Reply-To: <Pine.LNX.4.10.10012131213160.802-100000@penguin.transmeta.com>

On Wed, 13 Dec 2000, Linus Torvalds wrote:

> On Wed, 13 Dec 2000, Linus Torvalds wrote:
> > 
> > Hint: "ptep_mkdirty()".

<g> rather obvious oopsie.. once spotted.

> In case you wonder why the bug was so insidious, what this caused was two
> separate problems, both of them able to cause SIGSGV's. 
> 
> One: we didn't mark the page table entry dirty like we were supposed to.
> 
> Two: by making it writable, we also made the page shared, even if it
> wasn't supposed to be shared (so when the next process wrote to the page,
> if the swap page was shared with somebody else, the changes would show up
> even in the process that _didn't_ write to it).
> 
> And "ptep_mkdirty()" is only used by swapoff, so nothing else would show
> this. Which was why it hadn't been immediately obvious that anything was
> broken.

The terminal OOM problem is now gone and I haven't seen a SIGSEGV yet
running virgin source.

	IOU 5 bogo$$

	-Mike

(I still see something with IKD that _could_ be timing related troubles.
There are a couple of grubby fingerprints I need to wipe off, and some
churn/burn hours to be sure)

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  parent reply	other threads:[~2000-12-14  7:53 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <Pine.LNX.4.10.10012130805190.19301-100000@penguin.transmeta.com>
2000-12-13 17:23 ` Signal 11 - the continuing saga Linus Torvalds
2000-12-13 18:02   ` Mike Galbraith
2000-12-13 19:27     ` Linus Torvalds
2000-12-14  3:57       ` Mike Galbraith
2000-12-13 19:35     ` Linus Torvalds
2000-12-13 20:00       ` Gérard Roudier
2000-12-13 20:19       ` Linus Torvalds
2000-12-13 22:48         ` Rainer Mager
2000-12-17 23:27           ` Signal 11 - revisited Rainer Mager
2000-12-14  7:22         ` Mike Galbraith [this message]
2000-12-13 21:36       ` Signal 11 - the continuing saga Jeff V. Merkey
2000-12-11 23:24 Signal 11 Rainer Mager
2000-12-13  0:22 ` Signal 11 - the continuing saga Rainer Mager
2000-12-13  2:17   ` Jeff V. Merkey
2000-12-13  1:45     ` Rainer Mager
2000-12-13  4:29       ` Mike Galbraith
2000-12-13  9:34         ` Rainer Mager
2000-12-13 15:40           ` Mike Galbraith
2000-12-13  3:17     ` Linus Torvalds
2000-12-13  9:34       ` Rainer Mager
2000-12-13 17:43       ` Jeff V. Merkey

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