From: "Stephen C. Tweedie" <sct@redhat.com>
To: Kanoj Sarcar <kanoj@google.engr.sgi.com>
Cc: "Stephen C. Tweedie" <sct@redhat.com>, linux-mm@kvack.org
Subject: Re: filecache/swapcache questions
Date: Mon, 21 Jun 1999 17:57:36 +0100 (BST) [thread overview]
Message-ID: <14190.28416.483360.862142@dukat.scot.redhat.com> (raw)
In-Reply-To: <199906211646.JAA42546@google.engr.sgi.com>
Hi,
On Mon, 21 Jun 1999 09:46:19 -0700 (PDT), kanoj@google.engr.sgi.com
(Kanoj Sarcar) said:
> I don't agree with you about swapoff needing the mmap_sem. In my
> thinking, mmap_sem is needed to preserve the vma list, *if* you
> go to sleep while scanning the list. Updates to the vma fields/
> chain are protected by kernel_lock and mmap_sem.
No. mmap_sem protects both the vma list and the page tables. Page
faults hold the mmap semaphore both to protect the vma list and to
protect against concurrent pagins to the same page.
The swapper is currently exempt from the mmap_sem, so the paging code
needs to check whether the current pte has disappeared if it ever
blocks, but it assumes that we never have concurrent pagein occurring
(think threads). swapoff currently breaks that assumption.
--Stephen
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next prev parent reply other threads:[~1999-06-21 16:57 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-06-21 5:29 Kanoj Sarcar
1999-06-21 11:25 ` Stephen C. Tweedie
1999-06-21 16:46 ` Kanoj Sarcar
1999-06-21 16:57 ` Stephen C. Tweedie [this message]
1999-06-21 17:36 ` Kanoj Sarcar
1999-06-21 17:49 ` Stephen C. Tweedie
1999-06-21 18:46 ` Kanoj Sarcar
1999-06-21 23:44 ` Kanoj Sarcar
1999-06-24 22:23 ` Andrea Arcangeli
1999-06-24 23:55 ` Kanoj Sarcar
1999-06-25 0:26 ` Andrea Arcangeli
1999-06-28 1:48 ` filecache/swapcache questions [RFC] [RFT] [PATCH] kanoj-mm12-2.3.8 Fix swapoff races Kanoj Sarcar
1999-06-28 10:35 ` Andrea Arcangeli
1999-06-28 17:11 ` filecache/swapcache questions [RFC] [RFT] [PATCH] kanoj-mm12-2.3.8 Kanoj Sarcar
1999-06-28 16:32 ` filecache/swapcache questions [RFC] [RFT] [PATCH] kanoj-mm12-2.3.8 Fix swapoff races Stephen C. Tweedie
1999-06-28 17:25 ` Kanoj Sarcar
1999-06-28 20:40 ` Stephen C. Tweedie
1999-06-28 21:11 ` Kanoj Sarcar
1999-06-28 22:12 ` Stephen C. Tweedie
1999-06-28 23:43 ` Kanoj Sarcar
1999-06-29 11:44 ` Stephen C. Tweedie
1999-06-29 22:01 ` Kanoj Sarcar
1999-06-30 17:28 ` Stephen C. Tweedie
1999-06-30 18:05 ` Kanoj Sarcar
1999-06-28 19:39 ` Chuck Lever
1999-06-28 19:55 ` filecache/swapcache questions [RFC] [RFT] [PATCH] kanoj-mm12-2.3.8 Kanoj Sarcar
1999-06-28 20:33 ` Chuck Lever
1999-06-28 20:51 ` Kanoj Sarcar
1999-06-28 21:32 ` Chuck Lever
1999-06-28 21:38 ` Kanoj Sarcar
1999-06-28 21:50 ` Chuck Lever
1999-06-28 22:15 ` Kanoj Sarcar
1999-06-29 11:23 ` Stephen C. Tweedie
1999-06-29 17:36 ` Kanoj Sarcar
1999-06-28 22:22 ` Stephen C. Tweedie
1999-06-28 22:21 ` Stephen C. Tweedie
1999-06-28 22:57 ` Andrea Arcangeli
1999-06-29 2:13 ` Chuck Lever
1999-06-29 12:01 ` Stephen C. Tweedie
1999-06-29 12:32 ` Andrea Arcangeli
1999-06-30 15:59 ` Stephen C. Tweedie
1999-06-29 1:00 ` Chuck Lever
1999-06-28 22:08 ` Stephen C. Tweedie
1999-06-28 22:59 ` Andrea Arcangeli
1999-06-29 0:53 ` Chuck Lever
1999-06-29 11:14 ` Stephen C. Tweedie
1999-06-28 22:09 ` Stephen C. Tweedie
1999-06-28 20:45 ` filecache/swapcache questions [RFC] [RFT] [PATCH] kanoj-mm12-2.3.8 Fix swapoff races Stephen C. Tweedie
1999-06-28 21:14 ` Chuck Lever
1999-06-28 21:25 ` filecache/swapcache questions [RFC] [RFT] [PATCH] kanoj-mm12-2.3.8 Kanoj Sarcar
1999-06-28 22:15 ` filecache/swapcache questions [RFC] [RFT] [PATCH] kanoj-mm12-2.3.8 Fix swapoff races Stephen C. Tweedie
1999-06-28 22:48 ` Andrea Arcangeli
1999-06-29 1:29 ` Chuck Lever
1999-06-29 11:58 ` Stephen C. Tweedie
1999-06-29 12:09 ` Andrea Arcangeli
1999-06-29 15:27 ` Chuck Lever
1999-06-29 11:55 ` Stephen C. Tweedie
1999-06-29 20:08 ` Andrea Arcangeli
1999-06-28 22:36 ` filecache/swapcache questions Stephen C. Tweedie
1999-06-28 23:24 ` Kanoj Sarcar
-- strict thread matches above, loose matches on Subject: below --
1999-06-15 7:16 Kanoj Sarcar
1999-06-15 7:32 ` Rik van Riel
1999-06-15 15:51 ` Kanoj Sarcar
1999-06-15 20:24 ` Rik van Riel
1999-06-15 21:02 ` Kanoj Sarcar
1999-06-16 20:37 ` Andrea Arcangeli
1999-06-17 23:33 ` Stephen C. Tweedie
1999-06-18 0:20 ` Kanoj Sarcar
1999-06-18 17:00 ` Stephen C. Tweedie
1999-06-18 17:03 ` Kanoj Sarcar
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