From: "David S. Miller" <davem@redhat.com>
To: Hugh Dickins <hugh@veritas.com>
Cc: riel@redhat.com, marcelo.tosatti@cyclades.com,
Matt_Domsch@Dell.com, linux-kernel@vger.kernel.org,
benh@kernel.crashing.org
Subject: Re: [PATCH] page->flags corruption fix
Date: Wed, 8 Oct 2003 07:57:00 -0700 [thread overview]
Message-ID: <20031008075700.553e89f9.davem@redhat.com> (raw)
In-Reply-To: <Pine.LNX.4.44.0310081538170.3028-100000@localhost.localdomain>
On Wed, 8 Oct 2003 15:49:34 +0100 (BST)
Hugh Dickins <hugh@veritas.com> wrote:
> Seven atomic ops in a row, isn't that rather inefficient?
> The 2.6 version clears those PG_flags all together in one
> non-atomic op - but elsewhere, in prep_new_page.
>
> Is there an actual test case for why 2.4 now needs this change?
It's not a new bug, we've always had this bug in 2.4.x
There is so much code that does atomic bit ops asynchronously on
page->flags that it is therefore not safe for any context to make
non-atomic changes to the values there.
The patch Rik posted is the safest solution to this bug. If you
want to make it faster by creating a "mutliple bit" set of bitops
go right ahead, but be nice enough to make sure every single architecture
has an implementation before suggesting that the change gets merged
into 2.4.x
next prev parent reply other threads:[~2003-10-08 14:59 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-10-07 16:26 [PATCH] page->flags corruption fix Rik van Riel
2003-10-08 14:49 ` Hugh Dickins
2003-10-08 14:57 ` David S. Miller [this message]
2003-10-08 15:10 ` Rik van Riel
2003-10-08 15:47 ` Hugh Dickins
2003-10-08 15:52 ` Rik van Riel
-- strict thread matches above, loose matches on Subject: below --
2003-10-08 15:31 Matt_Domsch
2003-10-08 15:53 ` Hugh Dickins
2003-10-08 15:59 ` Rik van Riel
2003-10-08 17:15 ` Hugh Dickins
2003-10-08 17:41 ` Marcelo Tosatti
2003-10-08 17:52 ` Rik van Riel
2003-10-11 13:48 ` Andrea Arcangeli
2003-10-11 16:03 ` Andrea Arcangeli
2003-10-12 11:15 ` Hugh Dickins
2003-10-12 13:21 ` Andrea Arcangeli
2003-10-12 13:35 ` Andrea Arcangeli
2003-10-12 14:11 ` Rik van Riel
2003-10-12 14:36 ` Andrea Arcangeli
2003-10-12 17:20 ` Rik van Riel
2003-10-12 20:40 ` Andrea Arcangeli
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