linux-kernel - Re: [PATCH] Fix panic in __d_lookup with high dentry hashtable counts

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Date:	Tue, 17 Jan 2012 23:57:39 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	sivanich@....com
Cc:	linux-kernel@...r.kernel.org, viro@...IV.linux.org.uk,
	eric.dumazet@...il.com, kuznet@....inr.ac.ru, jmorris@...ei.org,
	yoshfuji@...ux-ipv6.org, kaber@...sh.net,
	paulmck@...ux.vnet.ibm.com, paul.gortmaker@...driver.com,
	akpm@...ux-foundation.org, jkosina@...e.cz, avi@...hat.com,
	linux-fsdevel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH] Fix panic in __d_lookup with high dentry hashtable
 counts

From: Dimitri Sivanich <sivanich@....com>
Date: Tue, 17 Jan 2012 15:05:41 -0600

> On Tue, Jan 17, 2012 at 12:22:29PM -0500, David Miller wrote:
>> To be honest I think this is overkill.
>> 
>> Supporting anything larger than a 32-bit hash mask is not even close
>> to being reasonable.  Nobody needs a 4GB hash table, not for anything.
>>
> Here is a patch that keeps the 32-bit hash mask.
> 
> 
>  
> When the number of dentry cache hash table entries gets too high
> (2147483648 entries), as happens by default on a 16TB system, use
> of a signed integer in the dcache_init() initialization loop prevents
> the dentry_hashtable from getting initialized, causing a panic in
> __d_lookup().  Fix this in dcache_init() and similar areas.
> 
> Signed-off-by: Dimitri Sivanich <sivanich@....com>

This looks good to me, thanks Dimitri:

Acked-by: David S. Miller <davem@...emloft.net>
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