Re: [PATCH 2.6.33-rc6] idr: revert misallocation bug fix

From: Tejun Heo <tj@kernel.org>
To: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	lkml <linux-kernel@vger.kernel.org>,
	dri-devel@lists.sourceforge.net, Dave Airlie <airlied@gmail.com>,
	Greg KH <greg@kroah.com>, Eric Paris <eparis@redhat.com>
Subject: Re: [PATCH 2.6.33-rc6] idr: revert misallocation bug fix
Date: Thu, 11 Feb 2010 17:52:05 +0900	[thread overview]
Message-ID: <4B73C535.7020405@kernel.org> (raw)
In-Reply-To: <1265317104.11442.29.camel@nimitz>

Hello,

On 02/05/2010 05:58 AM, Dave Hansen wrote:
> Bah.  I just ran into and bisected the X startup problem. :)
> 
> Let me know when you have a proper fix.  I can test on my machine for
> you.

Can you please test the following against the current mainline?

Thanks.

diff --git a/lib/idr.c b/lib/idr.c
index 1cac726..0dc7822 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -156,10 +156,12 @@ static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
 			id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
 
 			/* if already at the top layer, we need to grow */
-			if (!(p = pa[l])) {
+			if (id >= 1 << (idp->layers * IDR_BITS)) {
 				*starting_id = id;
 				return IDR_NEED_TO_GROW;
 			}
+			p = pa[l];
+			BUG_ON(!p);
 
 			/* If we need to go up one layer, continue the
 			 * loop; otherwise, restart from the top.


-- 
tejun
