From: Andrea Arcangeli <andrea@suse.de>
To: Kanoj Sarcar <kanoj@google.engr.sgi.com>
Cc: Ben LaHaise <bcrl@redhat.com>,
riel@nl.linux.org, Linus Torvalds <torvalds@transmeta.com>,
linux-mm@kvack.org
Subject: Re: [patch] take 2 Re: PG_swap_entry bug in recent kernels
Date: Sat, 8 Apr 2000 15:20:25 +0200 (CEST) [thread overview]
Message-ID: <Pine.LNX.4.21.0004081514470.559-100000@alpha.random> (raw)
In-Reply-To: <200004080037.RAA32924@google.engr.sgi.com>
On Fri, 7 Apr 2000, Kanoj Sarcar wrote:
>Okay, I think I found at least one reason why the lockpage was being done
>in lookup_swap_cache(). It was effectively to check the PageSwapCache bit,
>since shrink_mmap:__delete_from_swap_cache could race with a
>lookup_swap_cache.
shrink_mmap can't race with a find_get_cache. find_get_page increments the
reference count within the critical section and shrink_mmap checks the
page count and drop the page in one whole transaction within a mutually
exclusive critical section.
>Yes, I did notice the recent shrink_mmap SMP race fixes that you posted,
They weren't relative to the cache, but only to the LRU list
inserction/deletion. There wasn't races between shrink_mmap and
find_get_page and friends.
>now it _*might*_ be unneccesary to do a find_lock_page() in
>lookup_swap_cache() (just for this race). I will have to look at the
It isn't. Checking PageSwapCache while the page is locked is not
necessary. The only thing which can drop the page from the swap cache is
swapoff that will do that as soon as you do the unlock before returning
from lookup_swap_cache anyway.
Andrea
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next prev parent reply other threads:[~2000-04-08 13:20 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-04-03 22:22 PG_swap_entry bug in recent kernels Ben LaHaise
2000-04-04 15:06 ` Andrea Arcangeli
2000-04-04 15:46 ` Rik van Riel
2000-04-04 16:50 ` Andrea Arcangeli
2000-04-04 17:06 ` Ben LaHaise
2000-04-04 18:03 ` Andrea Arcangeli
2000-04-06 22:11 ` [patch] take 2 " Ben LaHaise
2000-04-07 10:45 ` Andrea Arcangeli
2000-04-07 11:29 ` Rik van Riel
2000-04-07 12:00 ` Andrea Arcangeli
2000-04-07 12:54 ` Rik van Riel
2000-04-07 13:14 ` Andrea Arcangeli
2000-04-07 20:12 ` Kanoj Sarcar
2000-04-07 23:26 ` Andrea Arcangeli
2000-04-08 0:11 ` Kanoj Sarcar
2000-04-08 0:37 ` Kanoj Sarcar
2000-04-08 13:20 ` Andrea Arcangeli [this message]
2000-04-08 21:39 ` Kanoj Sarcar
2000-04-08 23:02 ` Andrea Arcangeli
2000-04-08 23:18 ` Kanoj Sarcar
2000-04-08 23:58 ` Andrea Arcangeli
2000-04-08 13:30 ` Andrea Arcangeli
2000-04-08 17:39 ` Andrea Arcangeli
2000-04-07 23:54 ` Andrea Arcangeli
2000-04-08 0:15 ` Kanoj Sarcar
2000-04-08 13:14 ` Andrea Arcangeli
2000-04-08 21:47 ` Kanoj Sarcar
2000-04-08 23:10 ` Andrea Arcangeli
2000-04-08 23:21 ` Kanoj Sarcar
2000-04-08 23:39 ` Andrea Arcangeli
2000-04-09 0:40 ` Kanoj Sarcar
2000-04-10 8:55 ` andrea
2000-04-11 2:45 ` Kanoj Sarcar
2000-04-11 16:22 ` Andrea Arcangeli
2000-04-11 17:40 ` Rik van Riel
2000-04-11 18:20 ` Kanoj Sarcar
2000-04-21 18:23 ` Andrea Arcangeli
2000-04-21 21:00 ` Rik van Riel
2000-04-22 1:12 ` Andrea Arcangeli
2000-04-22 1:51 ` Linus Torvalds
2000-04-22 18:29 ` Rik van Riel
2000-04-22 19:58 ` Linus Torvalds
2000-04-11 18:26 ` Kanoj Sarcar
2000-04-10 19:10 ` Stephen C. Tweedie
2000-04-08 0:04 ` Andrea Arcangeli
[not found] <yttem7xstk2.fsf@vexeta.dc.fi.udc.es>
2000-04-23 0:52 ` Andrea Arcangeli
[not found] <yttk8ho26s8.fsf@vexeta.dc.fi.udc.es>
2000-04-23 16:07 ` Andrea Arcangeli
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