From: torvalds@transmeta.com (Linus Torvalds)
To: linux-kernel@vger.kernel.org
Subject: Re: Linux 2.4.1-ac15
Date: 21 Feb 2001 18:27:00 -0800 [thread overview]
Message-ID: <971tdk$10p$1@penguin.transmeta.com> (raw)
In-Reply-To: <E14VPXZ-0007HS-00@halfway> <E14VXxY-0001wy-00@the-village.bc.nu>
In article <E14VXxY-0001wy-00@the-village.bc.nu>,
Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
>> This is a while back, but I thought the solution Philipp and I came up
>> with was to simply used a rw semaphore for this, which was taken (read
>> only) on page fault if we have to scan the exception table.
>
>We can take page faults in interrupt handlers in 2.4 so I had to use a
>spinlock, but that sounds the same
Umm? The above doesn't really make sense.
We can take a page fault on the kernel region with the lazy page
directory filling, but that code will just set the PGD entry and exit
without taking any lock at all. So it basically ends up being an
"invisible" event.
Now, if an interrupt handler accesses kernel memory that just isn't
there, that has _always_ taken a page fault, and that case is not new to
2.4.x. In that case you would take the exception table lock, but that is
true in both 2.2.x and in 2.4.x.
Linus
next prev parent reply other threads:[~2001-02-22 2:27 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-02-15 23:15 Linux 2.4.1-ac15 Alan Cox
2001-02-19 9:47 ` Philipp Rumpf
2001-02-19 11:35 ` Alan Cox
2001-02-19 11:54 ` Philipp Rumpf
2001-02-19 16:03 ` Alan Cox
2001-02-19 16:21 ` Philipp Rumpf
2001-02-19 16:27 ` Alan Cox
2001-02-19 16:34 ` Philipp Rumpf
2001-02-19 16:41 ` Alan Cox
2001-02-19 16:48 ` Philipp Rumpf
2001-02-19 17:03 ` Alan Cox
2001-02-21 3:02 ` Rusty Russell
2001-02-21 12:01 ` Alan Cox
2001-02-22 2:05 ` Rusty Russell
2001-02-22 10:22 ` Alan Cox
2001-02-23 0:01 ` Philipp Rumpf
2001-02-22 2:27 ` Linus Torvalds [this message]
2001-02-22 10:29 ` Alan Cox
2001-02-23 20:40 ` Andrea Arcangeli
2001-02-23 21:09 ` Linus Torvalds
2001-02-24 4:04 ` Andrea Arcangeli
2001-02-24 4:54 ` Andrea Arcangeli
2001-02-19 11:54 ` Keith Owens
2001-02-19 12:15 ` Philipp Rumpf
2001-02-19 13:15 ` Keith Owens
2001-02-19 13:25 ` Christoph Hellwig
2001-02-19 21:32 ` Keith Owens
2001-02-19 13:36 ` Philipp Rumpf
2001-02-19 15:23 ` Manfred Spraul
2001-02-19 16:04 ` Alan Cox
2001-02-19 21:52 ` Keith Owens
2001-02-20 12:29 ` Philipp Rumpf
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