NetBSD Problem Report #36866
From martin@duskware.de Thu Aug 30 11:22:45 2007
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Date: Thu, 30 Aug 2007 11:21:47 +0000 (UTC)
From: ilfoglionascosto@netcat.it
Reply-To: ilfoglionascosto@netcat.it
To: netbsd-bugs-owner@NetBSD.org
Subject: Memory exhaustion umounting a null filesystem
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>Number: 36866
>Category: bin
>Synopsis: Memory exhaustion umounting a null filesystem
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: bin-bug-people
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Thu Aug 30 11:25:00 +0000 2007
>Originator: Claudio M.
>Release: NetBSD 4.0_BETA2
>Organization:
NetBSD Italia
>Environment:
NetBSD develop.clanix.org 4.0_BETA2 NetBSD 4.0_BETA2 (GENERIC) #0: Thu Jul 26 16:26:55 PDT 2007 builds@wb30:/home/builds/ab/netbsd-4/i386/200707260002Z-obj/home/builds/ab/netbsd-4/src/sys/arch/i386/compile/GENERIC i386
>Description:
I've tried to play with the null filesystem by mounting /dev/null into a test directory.
develop$ mkdir test ; sudo mount_null /dev/null test
mount_null: "test" is a relative path.
mount_null: using "/home/claudio/test" instead.
Indeed it has been mounted:
develop$ mount |grep test ; file test
/dev/null on /home/claudio/test type null (local)
test: character special (2/2)
Now, trying to umount it (also with the -f flag) the umount command never exit and the system freeze due to the memory exhaustion. I have just few seconds to check if the test directory has been umounted:
develop$ mount |grep test ; file test
test: directory
develop$
At this point i'm not able anymore to shutdown the system, kill the umount command or just type ls. I searched for the `-l' flag (lazy umount, as GNU ls) but it's not (yet?) implemented.
I hope to guessed the category (bin) since this seems to be an infinite loop somewhere in the umount code.
>How-To-Repeat:
Just mount /dev/null somewhere and umount it.
>Fix:
I'm not able to post any solution or workaround.
(Contact us)
$NetBSD: query-full-pr,v 1.39 2013/11/01 18:47:49 spz Exp $
$NetBSD: gnats_config.sh,v 1.8 2006/05/07 09:23:38 tsutsui Exp $
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