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From: "David S. Miller" <davem@redhat.com>
To: Linus Torvalds <torvalds@osdl.org>
Cc: wesolows@foobazco.org, willy@debian.org, andrea@suse.de,
	benh@kernel.crashing.org, akpm@osdl.org,
	linux-kernel@vger.kernel.org, mingo@elte.hu, bcrl@kvack.org,
	linux-mm@kvack.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH] ppc64: Fix possible race with set_pte on a present PTE
Date: Tue, 25 May 2004 13:57:48 -0700	[thread overview]
Message-ID: <20040525135748.296ba888.davem@redhat.com> (raw)
In-Reply-To: <Pine.LNX.4.58.0405251340160.9951@ppc970.osdl.org>

On Tue, 25 May 2004 13:49:57 -0700 (PDT)
Linus Torvalds <torvalds@osdl.org> wrote:

> So it sounds like the SWAP loop basically ends up being just something 
> like
 ...
> Right? Note that the reason we can do the "dirty and accessed bit both 
> set" case with a simple write is exactly because that's already the 
> "maximal" bits anybody can write to the thing, so we don't need to loop, 
> we can just write it directly.

I believe so.  So it's still possible for the mmu to write something
with less bits, ie. say we're adding dirty, we write dirty+accessed but the
TLB has the pre-dirty PTE and writes that with just the accessed bit set.

And this is exactly what you code is trying to handle.  Perfect.

WARNING: multiple messages have this Message-ID (diff)
From: "David S. Miller" <davem@redhat.com>
To: Linus Torvalds <torvalds@osdl.org>
Cc: wesolows@foobazco.org, willy@debian.org, andrea@suse.de,
	benh@kernel.crashing.org, akpm@osdl.org,
	linux-kernel@vger.kernel.org, mingo@elte.hu, bcrl@kvack.org,
	linux-mm@kvack.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH] ppc64: Fix possible race with set_pte on a present PTE
Date: Tue, 25 May 2004 13:57:48 -0700	[thread overview]
Message-ID: <20040525135748.296ba888.davem@redhat.com> (raw)
In-Reply-To: <Pine.LNX.4.58.0405251340160.9951@ppc970.osdl.org>

On Tue, 25 May 2004 13:49:57 -0700 (PDT)
Linus Torvalds <torvalds@osdl.org> wrote:

> So it sounds like the SWAP loop basically ends up being just something 
> like
 ...
> Right? Note that the reason we can do the "dirty and accessed bit both 
> set" case with a simple write is exactly because that's already the 
> "maximal" bits anybody can write to the thing, so we don't need to loop, 
> we can just write it directly.

I believe so.  So it's still possible for the mmu to write something
with less bits, ie. say we're adding dirty, we write dirty+accessed but the
TLB has the pre-dirty PTE and writes that with just the accessed bit set.

And this is exactly what you code is trying to handle.  Perfect.
--
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  reply	other threads:[~2004-05-25 20:58 UTC|newest]

Thread overview: 153+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-05-24  3:29 [PATCH] ppc64: Fix possible race with set_pte on a present PTE Benjamin Herrenschmidt
2004-05-24  3:47 ` Linus Torvalds
2004-05-24  4:13   ` Benjamin Herrenschmidt
2004-05-24  4:36     ` Linus Torvalds
2004-05-24  4:44       ` Benjamin Herrenschmidt
2004-05-24  5:10         ` Linus Torvalds
2004-05-24  5:10           ` Linus Torvalds
2004-05-24  5:34           ` Benjamin Herrenschmidt
2004-05-24  5:34             ` Benjamin Herrenschmidt
2004-05-24  5:38             ` Benjamin Herrenschmidt
2004-05-24  5:38               ` Benjamin Herrenschmidt
2004-05-24  5:52               ` Benjamin Herrenschmidt
2004-05-24  5:52                 ` Benjamin Herrenschmidt
2004-05-24  7:39           ` Ingo Molnar
2004-05-24  7:39             ` Ingo Molnar
2004-05-24  5:39             ` Benjamin Herrenschmidt
2004-05-24  5:39               ` Benjamin Herrenschmidt
2004-05-25  3:43           ` Andrea Arcangeli
2004-05-25  3:43             ` Andrea Arcangeli
2004-05-25  4:00             ` Linus Torvalds
2004-05-25  4:00               ` Linus Torvalds
2004-05-25  4:17               ` Benjamin Herrenschmidt
2004-05-25  4:17                 ` Benjamin Herrenschmidt
2004-05-25  4:37                 ` Andrea Arcangeli
2004-05-25  4:37                   ` Andrea Arcangeli
2004-05-25  4:40                   ` Benjamin Herrenschmidt
2004-05-25  4:40                     ` Benjamin Herrenschmidt
2004-05-25  4:20               ` Andrea Arcangeli
2004-05-25  4:20                 ` Andrea Arcangeli
2004-05-25  4:39                 ` Linus Torvalds
2004-05-25  4:39                   ` Linus Torvalds
2004-05-25  4:44                   ` Linus Torvalds
2004-05-25  4:44                     ` Linus Torvalds
2004-05-25  4:59                     ` Andrea Arcangeli
2004-05-25  4:59                       ` Andrea Arcangeli
2004-05-25  5:09                       ` Andrea Arcangeli
2004-05-25  5:09                         ` Andrea Arcangeli
2004-05-25  4:50                   ` Andrea Arcangeli
2004-05-25  4:50                     ` Andrea Arcangeli
2004-05-25  4:59                     ` Linus Torvalds
2004-05-25  4:59                       ` Linus Torvalds
2004-05-25  4:43                 ` David Mosberger
2004-05-25  4:43                   ` David Mosberger
2004-05-25  4:53                   ` Andrea Arcangeli
2004-05-25  4:53                     ` Andrea Arcangeli
2004-05-27 21:56                     ` David Mosberger
2004-05-27 21:56                       ` David Mosberger
2004-05-27 22:00                       ` Benjamin Herrenschmidt
2004-05-27 22:00                         ` Benjamin Herrenschmidt
2004-05-27 22:12                         ` David Mosberger
2004-05-27 22:12                           ` David Mosberger
2004-05-25 11:44               ` Matthew Wilcox
2004-05-25 11:44                 ` Matthew Wilcox
2004-05-25 14:48                 ` Linus Torvalds
2004-05-25 14:48                   ` Linus Torvalds
2004-05-25 15:35                   ` Keith M Wesolowski
2004-05-25 15:35                     ` Keith M Wesolowski
2004-05-25 16:19                     ` Linus Torvalds
2004-05-25 16:19                       ` Linus Torvalds
2004-05-25 17:25                       ` David S. Miller
2004-05-25 17:25                         ` David S. Miller
2004-05-25 17:49                         ` Linus Torvalds
2004-05-25 17:49                           ` Linus Torvalds
2004-05-25 17:54                           ` David S. Miller
2004-05-25 17:54                             ` David S. Miller
2004-05-25 18:05                             ` Linus Torvalds
2004-05-25 18:05                               ` Linus Torvalds
2004-05-25 20:30                               ` Linus Torvalds
2004-05-25 20:30                                 ` Linus Torvalds
2004-05-25 20:35                               ` David S. Miller
2004-05-25 20:35                                 ` David S. Miller
2004-05-25 20:35                                 ` David S. Miller
2004-05-25 20:49                                 ` Linus Torvalds
2004-05-25 20:49                                   ` Linus Torvalds
2004-05-25 20:57                                   ` David S. Miller [this message]
2004-05-25 20:57                                     ` David S. Miller
2004-05-26  6:20                                   ` Keith M Wesolowski
2004-05-26  6:20                                     ` Keith M Wesolowski
2004-05-25 21:40                               ` Benjamin Herrenschmidt
2004-05-25 21:40                                 ` Benjamin Herrenschmidt
2004-05-25 21:54                                 ` Linus Torvalds
2004-05-25 21:54                                   ` Linus Torvalds
2004-05-25 22:00                                   ` Linus Torvalds
2004-05-25 22:00                                     ` Linus Torvalds
2004-05-25 22:07                                     ` Benjamin Herrenschmidt
2004-05-25 22:07                                       ` Benjamin Herrenschmidt
2004-05-25 22:14                                       ` Linus Torvalds
2004-05-25 22:14                                         ` Linus Torvalds
2004-05-26  0:21                                         ` Benjamin Herrenschmidt
2004-05-26  0:21                                           ` Benjamin Herrenschmidt
2004-05-26  0:50                                           ` Linus Torvalds
2004-05-26  0:50                                             ` Linus Torvalds
2004-05-26  3:25                                             ` Benjamin Herrenschmidt
2004-05-26  3:25                                               ` Benjamin Herrenschmidt
2004-05-26  4:08                                               ` Linus Torvalds
2004-05-26  4:08                                                 ` Linus Torvalds
2004-05-26  4:12                                                 ` Benjamin Herrenschmidt
2004-05-26  4:12                                                   ` Benjamin Herrenschmidt
2004-05-26  4:18                                                   ` Benjamin Herrenschmidt
2004-05-26  4:18                                                     ` Benjamin Herrenschmidt
2004-05-26  4:50                                                     ` Linus Torvalds
2004-05-26  4:50                                                       ` Linus Torvalds
2004-05-26  4:49                                                       ` Benjamin Herrenschmidt
2004-05-26  4:49                                                         ` Benjamin Herrenschmidt
2004-05-26  4:28                                                   ` Linus Torvalds
2004-05-26  4:28                                                     ` Linus Torvalds
2004-05-26  4:46                                                 ` Benjamin Herrenschmidt
2004-05-26  4:46                                                   ` Benjamin Herrenschmidt
2004-05-26  4:54                                                   ` Linus Torvalds
2004-05-26  4:54                                                     ` Linus Torvalds
2004-05-26  4:55                                                     ` Benjamin Herrenschmidt
2004-05-26  4:55                                                       ` Benjamin Herrenschmidt
2004-05-26  5:41                                                     ` Benjamin Herrenschmidt
2004-05-26  5:41                                                       ` Benjamin Herrenschmidt
2004-05-26  5:59                                                     ` [PATCH] (signoff) " Benjamin Herrenschmidt
2004-05-26  5:59                                                       ` Benjamin Herrenschmidt
2004-05-26  6:55                                                       ` Benjamin Herrenschmidt
2004-05-26  6:55                                                         ` Benjamin Herrenschmidt
2004-05-26  7:11                                                         ` [PATCH] ppc32 implementation of ptep_set_access_flags Benjamin Herrenschmidt
2004-05-26 15:22                                                           ` Linus Torvalds
2004-05-26 18:49                                                             ` David S. Miller
2004-05-26 21:43                                                             ` Benjamin Herrenschmidt
2004-05-28  1:29                                                             ` David Mosberger
2004-05-25 22:05                                   ` [PATCH] ppc64: Fix possible race with set_pte on a present PTE Benjamin Herrenschmidt
2004-05-25 22:05                                     ` Benjamin Herrenschmidt
2004-05-25 22:09                                 ` Linus Torvalds
2004-05-25 22:09                                   ` Linus Torvalds
2004-05-25 22:19                                   ` Benjamin Herrenschmidt
2004-05-25 22:19                                     ` Benjamin Herrenschmidt
2004-05-25 22:24                                     ` Linus Torvalds
2004-05-25 22:24                                       ` Linus Torvalds
2004-05-25 21:27                   ` Andrea Arcangeli
2004-05-25 21:27                     ` Andrea Arcangeli
2004-05-25 21:43                     ` Linus Torvalds
2004-05-25 21:43                       ` Linus Torvalds
2004-05-25 21:55                       ` Andrea Arcangeli
2004-05-25 21:55                         ` Andrea Arcangeli
2004-05-25 22:01                         ` Linus Torvalds
2004-05-25 22:01                           ` Linus Torvalds
2004-05-25 22:18                           ` Ivan Kokshaysky
2004-05-25 22:18                             ` Ivan Kokshaysky
2004-05-25 22:42                             ` Andrea Arcangeli
2004-05-25 22:42                               ` Andrea Arcangeli
2004-05-26  2:26                               ` Linus Torvalds
2004-05-26  2:26                                 ` Linus Torvalds
2004-05-26  7:06                                 ` Andrea Arcangeli
2004-05-26  7:06                                   ` Andrea Arcangeli
2004-05-25 21:44                     ` Andrea Arcangeli
2004-05-25 21:44                       ` Andrea Arcangeli
  -- strict thread matches above, loose matches on Subject: below --
2004-06-01 12:04 Martin Schwidefsky
2004-06-01 12:04 ` Martin Schwidefsky
2004-06-01 12:10 Martin Schwidefsky
2004-06-01 12:10 ` Martin Schwidefsky

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