From: Steve Lord <lord@xfs.org>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: negative dentry_stat.nr_unused causes aggressive dcache pruning
Date: Thu, 09 Dec 2004 14:54:46 -0600 [thread overview]
Message-ID: <41B8BB96.4040006@xfs.org> (raw)
In-Reply-To: <20041209020919.6f17e322.akpm@osdl.org>
Andrew Morton wrote:
> Steve Lord <lord@xfs.org> wrote:
>
>>I have seen this stat go negative (just from booting up a multi cpu box),
>> and looking at the code, it is manipulated without locking in a number
>> of places. I have only seen this in real life on a 2.4 kernel, but 2.6
>> also looks vulnerable.
>
>
> In 2.6, both dentry_stat.nr_unused and dentry_stat.nr_dentry are covered
> by dcache_lock. I just double-checked and all seems well.
>
I still do not know exactly how the count gets negative, but I tracked it
down to a user space app from emulex called HBAanywhere. The only thing I
can see this doing which might be related is attempting to open a lot of
non-existant /proc entries:
/proc/scsi//120
/proc/scsi//121
etc...
Yes there is a // in there.
I ran with a BUG call if we manipulate nr_unused without the dcache lock
and it never tripped. All very wierd.
Steve
next prev parent reply other threads:[~2004-12-09 20:59 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-08 22:16 negative dentry_stat.nr_unused causes aggressive dcache pruning Steve Lord
2004-12-08 23:01 ` Greg Banks
2004-12-09 10:09 ` Andrew Morton
2004-12-09 16:33 ` Steve Lord
2004-12-09 20:54 ` Steve Lord [this message]
2004-12-09 21:19 ` Andrew Morton
2004-12-09 21:51 ` Steve Lord
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