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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 01:54:02 +0200 (CEST)	[thread overview]
Message-ID: <Pine.LNX.4.21.0004080142340.2121-100000@alpha.random> (raw)
In-Reply-To: <200004072012.NAA10407@google.engr.sgi.com>

On Fri, 7 Apr 2000, Kanoj Sarcar wrote:

>[..] A bigger problem might
>be that you are violating lock orders when you grab the vmlist_lock
>from inside code that already has tasklist_lock in readmode [..]

Conceptually it's the obviously right locking order. The mm exists in
function of a task struct. So first grabbing the tasklist lock, finding
the task_struct and then locking its mm before playing with it looks the
natural ordering of things and how things should be done.

BTW, swap_out() always used the same locking order that I added to swapoff
so if my patch is wrong, swap_out() is always been wrong as well ;).

I had a fast look and it seems nobody is going to harm swap_out and
swapoff but if somebody is using the inverse lock I'd much prefer to fix
that path because the locking design of swapoff and swap_out looks the
obviously right one to me.

Andrea

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  parent reply	other threads:[~2000-04-07 23:54 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
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 [this message]
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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